JP4253207B2 - Semiconductor light emitting device manufacturing method, semiconductor light emitting device, surface emitting semiconductor laser device manufacturing method, surface light emitting semiconductor laser device, surface emitting semiconductor laser array, optical transmission module, optical transmission / reception module, and optical communication system - Google Patents

Description

【００６５】
図５において、ＧａＩｎＮＡｓ／ＧａＡｓ２重量子井戸構造に対応して、活性層２０４中に２つの窒素ピークが見られる。そして、活性層２０４において、酸素のピークが検出されている。しかし、ＮとＡｌを含まない中間層２０３における酸素濃度は、活性層２０４の酸素濃度よりも約１桁低い濃度となっている。
【００６６】
一方、クラッド層２０２をＧａＩｎＰとし、中間層２０３をＧａＡｓとし、活性層２０４をＧａＩｎＮＡｓ／ＧａＡｓ２重量子井戸構造として構成した半導体発光素子について、酸素濃度の深さ方向分布を測定した場合には、活性層２０４中の酸素濃度はバックグラウンドレベルであった。
【００６７】
すなわち、窒素化合物原料と有機金属Ａｌ原料を用いて、１台のエピタキシャル成長装置により、基板（２０１）と窒素を含む活性層（２０４）との間にＡｌを含む半導体層（２０２）を設けた半導体発光素子を連続的に結晶成長すると、窒素を含む活性層（２０４）中に酸素が取りこまれることが本願の発明者の実験により明らかとなった。活性層（２０４）に取りこまれた酸素は非発光再結合準位を形成するため、活性層（２０４）の発光効率を低下させてしまう。この活性層（２０４）に取りこまれた酸素が、基板（２０１）と窒素を含む活性層（２０４）との間にＡｌを含む半導体層（２０２）を設けた半導体発光素子における発光効率を低下させる原因であることが新たに判明した。この酸素の起源は、装置内に残留している酸素を含んだ物質、または、窒素化合物原料中に不純物として含まれる酸素を含んだ物質と考えられる。
【００６８】
次に、酸素の取りこまれる原因について検討した。図６は、図５と同じ試料のＡｌ濃度の深さ方向分布を示す図である。なお、測定はＳＩＭＳによって行った。また、次表（表２）に測定条件を示す。
【００６９】
【表２】

【００７０】
図６から、本来Ａｌ原料を導入していない活性層２０４において、Ａｌが検出されている。しかし、Ａｌを含む半導体層（クラッド層）２０２，２０５に隣接した中間層（ＧａＡｓ層）２０３においては、Ａｌ濃度は活性層２０４よりも約１桁低い濃度となっている。これは、活性層２０４中のＡｌがＡｌを含む半導体層（クラッド層）２０２，２０５から拡散，置換して混入したものではないことを示している。
【００７１】
一方、ＧａＩｎＰのようにＡｌを含まない半導体層上に窒素を含む活性層を成長した場合には、活性層中にＡｌは検出されなかった。
【００７２】
従って、図６において活性層２０４中に検出されたＡｌは、成長室内またはガス供給ラインに残留したＡｌ原料，Ａｌ反応物，Ａｌ化合物，Ａｌのうちの少なくとも１つが、窒素化合物原料または窒素化合物原料中の不純物（水分等）と結合して活性層２０４中に取りこまれたものである。すなわち、窒素化合物原料と有機金属Ａｌ原料を用いて、１台のエピタキシャル成長装置により、基板と窒素を含む活性層との間にＡｌを含む半導体層を設けた半導体発光素子を連続的に結晶成長すると、窒素を含む活性層中に自然にＡｌが取りこまてしまうことが本願の発明者により新たにわかった。
【００７３】
図５に示した同じ素子における、窒素と酸素濃度の深さ方向分布と比較すると、２重量子井戸活性層２０４中の２つの酸素ピークプロファイルは、窒素濃度のピークプロファイルと対応しておらず、図６のＡｌ濃度プロファイルと対応している。このことから、ＧａＩｎＮＡｓ井戸層中の酸素不純物は、窒素原料と共に取りこまれるというよりも、むしろ井戸層中に取りこまれたＡｌと結合して一緒に取りこまれていることが明らかとなった。すなわち、成長室内に残留したＡｌ原料，Ａｌ反応物，Ａｌ化合物，Ａｌのうちの少なくとも１つが窒素化合物原料と接触すると、Ａｌと窒素化合物原料中に含まれる水分またはガスラインや反応室中に残留する水分などの酸素を含んだ物質とが結合して、活性層２０４中にＡｌと酸素が取りこまれる。この活性層２０４に取り込まれた酸素が活性層２０４の発光効率を低下させることが本願の発明者の実験により初めて明らかとなった。
【００７４】
通常のＭＢＥ法で作製した場合には、基板と窒素を含む活性層との間にＡｌを含む半導体層を設けた半導体発光素子における発光効率低下については報告されていない。
【００７５】
これは、ＭＢＥ法は超減圧（高真空中）で結晶成長が行われるのに対して、ＭＯＣＶＤ法は通常数１０Ｔｏｒｒから大気圧程度と、ＭＢＥ法に比べて反応室の圧力が高いため、平均自由行程が圧倒的に短く、供給された原料やキャリアガス等が反応室等でＡｌ系残留物と接触，反応するためと考えられる。
【００７６】
よって、ＭＯＣＶＤ法のように、反応室やガスラインの圧力が高い成長方法の場合、これを改善するためには、少なくとも装置内に残留したＡｌが窒素を含む活性層成長時に酸素とともに膜中に取りこまれないように、Ａｌ系残留物を除去する工程を設けることが必要であることがわかった。
【００７７】
本発明は、ｐ型半導体層を形成した後に窒素を含む活性層を形成する構造とし、ｐ型半導体層中にＡｌＡｓを主成分とする被選択酸化層を配置し、配置された被選択酸化層の一部を選択的に酸化して電流狭窄構造を形成する半導体発光素子を作製するときに、装置内に残留したＡｌが窒素を含む活性層成長時に酸素とともに膜中に取りこまれないようにすることを意図している。
【００７８】
第１の実施形態
このため、本発明の第１の実施形態の半導体発光素子の製造方法は、窒素を含む活性層と半導体基板との間にｐ型半導体層を有し、ｐ型半導体層中にＡｌＡｓを主成分とする被選択酸化層を配置し、配置された被選択酸化層の一部を選択的に酸化して電流狭窄構造を形成する半導体発光素子の製造方法であって、被選択酸化層の成長後、窒素を含む活性層の成長開始までの間に、窒素化合物原料または窒素化合物原料中に含まれる不純物が触れる場所となるガス供給ライン中もしくは成長室内に残留したＡｌ原料，Ａｌ反応物，Ａｌ化合物，Ａｌのうちの少なくとも１つを除去する工程を設けることを特徴としている。
【００７９】
上述したように、窒素を含む活性層と半導体基板との間にｐ型半導体層を有し、ｐ型半導体層中にＡｌＡｓを主成分とする被選択酸化層を配置し、配置された被選択酸化層の一部を選択的に酸化して電流狭窄構造を形成する半導体発光素子の製造方法では、Ａｌ系残留物が非発光再結合の原因となる酸素を活性層（窒素を含んだ活性層）に取りこむ原因となっているので、この第１の実施形態のように、Ａｌを含んだ層を形成後、窒素を含んだ活性層の成長の前までに、反応室側壁，加熱帯，基板を保持する治具等に残留しているＡｌ系残留物を除去する工程を設けることで、活性層への酸素の取り込みを抑えることができる。
【００８０】
本発明の第１の実施形態の手法によって、窒素を含む活性層中のＡｌ濃度を１×１０^１９ｃｍ^−３以下に低減することが可能となり、これにより、半導体発光素子の室温連続発振が可能となる。さらに、窒素を含む活性層中のＡｌ濃度を２×１０^１８ｃｍ^−３以下に低減するときには、Ａｌを含まない半導体層上に形成した場合と同等の発光特性が得られる。
【００８１】
次表（表３）は、ＡｌＧａＡｓをクラッド層（Ａｌを含む層）とし、ＧａＩｎＮＡｓ２重量子井戸構造（窒素を含む層）を活性層としたブロードストライプレーザを試作して閾電流密度を評価した結果を示している。
【００８２】
【表３】

【００８３】
表３から、Ａｌを構成元素として含む半導体層に、窒素を含む活性層を連続的に形成する構造においては、活性層中に２×１０^１９ｃｍ^−３以上のＡｌが含まれると、１×１０^１８ｃｍ^−３以上の酸素が取りこまれ、閾電流密度は１０ｋＡ／ｃｍ^２以上と著しく高い値となる。これに対し、活性層中のＡｌ濃度を１×１０^１９ｃｍ^−３以下に低減することにより、活性層中の酸素濃度が１×１０^１８ｃｍ^−３以下に低減され、閾電流密度２〜３ｋＡ／ｃｍ^２でブロードストライプレーザが発振した。ブロードストライプレーザの閾電流密度が数ｋＡ／ｃｍ^２以下の活性層品質であれば、室温連続発振が可能である。従って、窒素を含む活性層中のＡｌ濃度を２×１０^１９ｃｍ^−３以下に抑制することにより、室温連続発振可能な半導体レーザを作製することが可能となる。
【００８４】
このように、本発明では、窒素を含む活性層と半導体基板との間にｐ型半導体層を有し、ｐ型半導体層中にＡｌＡｓを主成分とする被選択酸化層を配置し、配置された被選択酸化層の一部を選択的に酸化して電流狭窄構造を形成する半導体発光素子の製造方法であって、被選択酸化層の成長後、窒素を含む活性層の成長開始までの間に、窒素化合物原料または窒素化合物原料中に含まれる不純物が触れる場所となるガス供給ライン中もしくは成長室内に残留したＡｌ原料，Ａｌ反応物，Ａｌ化合物，Ａｌのうちの少なくとも１つを除去する工程を設けるので、窒素を含んだ活性層の成長時に酸素が取り込まれるのを低減でき、Ａｌを含んだ半導体層の上部に窒素を含んだ活性層が形成される半導体発光素子においても、発光効率を低減させることなく半導体発光素子を結晶成長することができる。
【００８５】
なお、上述した本発明の第１の実施形態の半導体発光素子の製造方法において、窒素化合物原料または窒素化合物原料中に含まれる不純物が触れる場所となるガス供給ライン中もしくは成長室内に残留したＡｌ原料，Ａｌ反応物，Ａｌ化合物，Ａｌのうちの少なくとも１つを除去する工程は、成長を中断し、キャリアガスでガス供給ラインもしくは成長室をパージすることによって行なうことができる。
【００８６】
すなわち、上述したように、Ａｌ系残留物が非発光再結合の原因となる酸素を活性層（窒素を含んだ活性層）に取りこむ原因となっているので、Ａｌを含んだ半導体層を成長後、窒素を含んだ活性層成長の前までに、成長を中断して、キャリアガスを供給してパージすることで、反応室側壁，加熱帯，基板を保持する治具等に残留しているＡｌ系残留物を除去することができ、活性層への酸素の取り込みを抑えることができる。通常、ＭＯＣＶＤでは、キャリアガスとして水素（Ｈ_２）ガスが用いられるが、窒素ガス（Ｎ_２）などの不活性ガスを用いることもできる。また、成長中断しているので、この成長中断界面をＳＩＭＳ分析によれば酸素（Ｏ）が観察されるであろう。
【００８７】
また、上記成長中断中に、サセプターをベーキングすることもできる。
【００８８】
すなわち、サセプターを加熱することで、反応室側壁，加熱帯，基板を保持する治具等に残留しているＡｌ系残留物が蒸発，反応しやすくなるので、Ａｌ系残留物を除去する効果が高くなる。また、結晶成長はサセプターを加熱して行われるので、成長を中断して同様に加熱すれば良く、従って、成長中断中のサセプターのベーキングは容易にできる。なお、このとき、ベーキング温度は、結晶成長時の温度よりも高くするのが好ましい。また、被成長基板は、別室に移動しても良く、別室に移動せずにそのまま行っても良い。そのまま行う場合は、Ｖ族元素が成長途中の被成長基板から蒸発，脱離しないようにするために、Ｖ族原料を供給して行うのが望ましい。
【００８９】
また、上述した第１の実施形態の半導体発光素子の製造方法において、被選択酸化層の成長後、窒素を含む活性層の成長開始までの間に、窒素化合物原料または窒素化合物原料中に含まれる不純物が触れる場所となるガス供給ライン中もしくは成長室内に残留したＡｌ原料，Ａｌ反応物，Ａｌ化合物，Ａｌのうちの少なくとも１つを除去するのに、エッチングガスを成長室に供給することもできる。
【００９０】
すなわち、Ａｌを含んだ半導体層を成長後、窒素を含んだ活性層の成長の前までに、反応室側壁，加熱帯，基板を保持する治具等に残留しているＡｌ系残留物と反応し除去することのできるガス（エッチングガス）を反応室に供給することで、活性層への酸素の取り込みを抑えることができ、発光効率の高い半導体発光素子を作製することができる。
【００９１】
なお、Ａｌ系残留物と反応し除去することのできるガス（エッチングガス）としては、有機系窒素化合物ガスを用いることができる。ここで、有機系窒素化合物ガスとしては、ＤＭＨｙガスが挙げられ、上述のように窒素を含んだ活性層の成長時に、有機系窒素化合物ガスの一つであるＤＭＨｙガスをＤＭＨｙシリンダーを用いて反応室に供給すると、Ａｌ系残留物と反応し、Ａｌ系残留物を除去することができる。
【００９２】
このように、Ａｌを含んだ半導体層を成長後、窒素を含んだ活性層成長の前までに、有機系窒素化合物ガスを供給すると、この有機系窒素化合物ガスは、反応室側壁，加熱帯，基板を保持する治具等に残留しているＡｌ系残留物と反応して、Ａｌ系残留物を除去することができ、これにより、活性層への酸素の取り込みを抑えることができる。更に、エッチングガスとして、窒素を含む活性層の窒素原料と同じガスを用いると、特別にガスラインを追加する必要がないので好ましい。
【００９３】
また、上記エッチングガスとして、酸素（Ｏ）を含むガスを用いることもできる。すなわち、Ａｌ系残留物と反応し除去することのできるガス（エッチングガス）として、Ｏ_２，Ｈ_２Ｏ等の酸素を含んだガスを用いることもできる。
【００９４】
上述したように、窒素を含んだ活性層の成長時にＡｌとともに酸素が活性層に取りこまれることがわかっている。従って、Ｏ_２，Ｈ_２Ｏ等の酸素を含んだガスはＡｌ系残留物と反応することがわかる。これによって、Ａｌを含んだ半導体層の成長後、窒素を含んだ活性層の成長の前までに、Ｏ_２，Ｈ_２Ｏ等の酸素を含んだガスを供給すると、このガスは、反応室側壁，加熱帯，基板を保持する治具等に残留しているＡｌ系残留物と反応して、Ａｌ系残留物を除去することができ、これにより、活性層への酸素の取り込みを抑えることができる。図６のＳＩＭＳプロファイルを見るとわかるように、窒素を含んだ活性層の１層目に多くのＡｌが取りこまれていて、２層目にはほとんど取り込まれないことから、ごくわずかの酸素を含んだガスを供給するだけでＡｌ系残留物を除去することができる。もちろん、過剰に供給した酸素を含んだガスは、活性層の成長前に除去する必要があるので、あまり過剰にならない適量を供給することが望ましい（逆に酸素を含んだガスの除外が困難になるからである）。
【００９５】
また、上記エッチングガスとして、塩素（Ｃｌ）を含むガスを用いることもできる。例えばＨＣｌのような塩素系化合物ガスは、成長室内の反応生成堆積物と反応して、エッチング除去する効果がある。従って、Ａｌを含んだ半導体層の成長後、窒素を含んだ活性層の成長の前までに、塩素系化合物ガスを供給すると、この塩素系化合物ガスは、反応室側壁，加熱帯，基板を保持する治具等に残留しているＡｌ系残留物と反応して、Ａｌ系残留物を除去することができ、これによって、活性層への酸素の取り込みを抑えることができる。なお、ＨＣｌガスはガスシリンダーに充填して使用することができる。この場合、塩素系ガスによる装置内部の金属部分の腐食を防止するため、酸素，水分等が少ない高純度のものが好ましい。
【００９６】
第２の実施形態
本発明の第２の実施形態の半導体発光素子の製造方法は、窒素を含む活性層と半導体基板との間にｐ型半導体層を有し、ｐ型半導体層中にＡｌＡｓを主成分とする被選択酸化層を配置し、配置された被選択酸化層の一部を選択的に酸化して電流狭窄構造を形成し、また、被選択酸化層と窒素を含む活性層との間に、少なくとも一層のＧａＩｎＰＡｓ層、または、ＧａＩｎＰ層、または、ＧａＰＡｓ層を形成する半導体発光素子の製造方法であって、被選択酸化層の成長後、前記ＧａＩｎＰＡｓ層、または、ＧａＩｎＰ層、または、ＧａＰＡｓ層の成長が完了するまでの間に、窒素化合物原料または窒素化合物原料中に含まれる不純物が触れる場所となるガス供給ライン中もしくは成長室内に残留したＡｌ原料，Ａｌ反応物，Ａｌ化合物，Ａｌのうちの少なくとも１つを除去する工程を設けることを特徴としている。
【００９７】
この第２の実施形態では、キャリアの注入されない活性領域外で成長中断してＡｌ系残留物を除去することで、残留Ａｌに起因する非発光再結合や、Ａｌ系残留物除去工程に起因する非発光再結合により、発光効率が低下することを抑制できる。
【００９８】
なお、上述した本発明の第２の実施形態の半導体発光素子の製造方法において、窒素化合物原料または窒素化合物原料中に含まれる不純物が触れる場所となるガス供給ライン中もしくは成長室内に残留したＡｌ原料，Ａｌ反応物，Ａｌ化合物，Ａｌのうちの少なくとも１つを除去する工程は、成長を中断し、キャリアガスで、ガス供給ラインもしくは成長室をパージすることによって行なうことができる。
【００９９】
すなわち、前述したように、Ａｌ系残留物が非発光再結合の原因となる酸素を活性層（窒素を含んだ活性層）に取りこむ原因となっているので、Ａｌを含んだ半導体層を成長後、窒素を含んだ活性層成長の前までに、成長を中断して、キャリアガスを供給してパージすることで、反応室側壁，加熱帯，基板を保持する治具等に残留しているＡｌ系残留物を除去することができ、活性層への酸素の取り込みを抑えることができる。通常、ＭＯＣＶＤでは、キャリアガスとして水素（Ｈ_２）ガスが用いられるが、窒素ガス（Ｎ_２）などの不活性ガスを用いることもできる。また、成長中断しているので、この成長中断界面をＳＩＭＳ分析によれば酸素（Ｏ）が観察されるであろう。
【０１００】
また、上記成長中断中に、サセプターをベーキングすることもできる。
【０１０１】
すなわち、サセプターを加熱することで、反応室側壁，加熱帯，基板を保持する治具等に残留しているＡｌ系残留物が蒸発，反応しやすくなるので、Ａｌ系残留物を除去する効果が高くなる。また、結晶成長はサセプターを加熱して行われるので、成長を中断して同様に加熱すれば良く、従って、成長中断中のサセプターのベーキングは容易にできる。なお、このとき、ベーキング温度は、結晶成長時の温度よりも高くするのが好ましい。また、被成長基板は、別室に移動しても良く、別室に移動せずにそのまま行っても良い。そのまま行う場合は、Ｖ族元素が成長途中の被成長基板から蒸発，脱離しないようにするために、Ｖ族原料を供給して行うのが望ましい。
【０１０２】
また、上述した第２の実施形態の半導体発光素子の製造方法において、被選択酸化層の成長後、窒素を含む活性層の成長開始までの間に、窒素化合物原料または窒素化合物原料中に含まれる不純物が触れる場所となるガス供給ライン中もしくは成長室内に残留したＡｌ原料，Ａｌ反応物，Ａｌ化合物，Ａｌのうちの少なくとも１つを除去するのに、エッチングガスを成長室に供給することもできる。
【０１０３】
すなわち、Ａｌを含んだ半導体層を成長後、窒素を含んだ活性層の成長の前までに、反応室側壁，加熱帯，基板を保持する治具等に残留しているＡｌ系残留物と反応し除去することのできるガス（エッチングガス）を反応室に供給することで、活性層への酸素の取り込みを抑えることができ、発光効率の高い半導体発光素子を作製することができる。
【０１０４】
なお、Ａｌ系残留物と反応し除去することのできるガス（エッチングガス）としては、有機系窒素化合物ガスを用いることができる。ここで、有機系窒素化合物ガスとしては、ＤＭＨｙガスが挙げられ、上述のように窒素を含んだ活性層の成長時に、有機系窒素化合物ガスの一つであるＤＭＨｙガスをＤＭＨｙシリンダーを用いて反応室に供給すると、Ａｌ系残留物と反応し、Ａｌ系残留物を除去することができる。
【０１０５】
このように、Ａｌを含んだ半導体層を成長後、窒素を含んだ活性層成長の前までに、有機系窒素化合物ガスを供給すると、この有機系窒素化合物ガスは、反応室側壁，加熱帯，基板を保持する治具等に残留しているＡｌ系残留物と反応して、Ａｌ系残留物を除去することができ、これにより、活性層への酸素の取り込みを抑えることができる。更に、エッチングガスとして、窒素を含む活性層の窒素原料と同じガスを用いると、特別にガスラインを追加する必要がないので好ましい。
【０１０６】
また、上記エッチングガスとして、酸素（Ｏ）を含むガスを用いることもできる。すなわち、Ａｌ系残留物と反応し除去することのできるガス（エッチングガス）として、Ｏ_２，Ｈ_２Ｏ等の酸素を含んだガスを用いることもできる。
【０１０７】
上述したように、窒素を含んだ活性層の成長時にＡｌとともに酸素が活性層に取りこまれることがわかっている。従って、Ｏ_２，Ｈ_２Ｏ等の酸素を含んだガスはＡｌ系残留物と反応することがわかる。これによって、Ａｌを含んだ半導体層の成長後、窒素を含んだ活性層の成長の前までに、Ｏ_２，Ｈ_２Ｏ等の酸素を含んだガスを供給すると、このガスは、反応室側壁，加熱帯，基板を保持する治具等に残留しているＡｌ系残留物と反応して、Ａｌ系残留物を除去することができ、これにより、活性層への酸素の取り込みを抑えることができる。図６のＳＩＭＳプロファイルを見るとわかるように、窒素を含んだ活性層の１層目に多くのＡｌが取りこまれていて、２層目にはほとんど取り込まれないことから、ごくわずかの酸素を含んだガスを供給するだけでＡｌ系残留物を除去することができる。もちろん、過剰に供給した酸素を含んだガスは、活性層の成長前に除去する必要があるので、あまり過剰にならない適量を供給することが望ましい（逆に酸素を含んだガスの除外が困難になるからである）。
【０１０８】
また、上記エッチングガスとして、塩素（Ｃｌ）を含むガスを用いることもできる。例えばＨＣｌのような塩素系化合物ガスは、成長室内の反応生成堆積物と反応して、エッチング除去する効果がある。従って、Ａｌを含んだ半導体層の成長後、窒素を含んだ活性層の成長の前までに、塩素系化合物ガスを供給すると、この塩素系化合物ガスは、反応室側壁，加熱帯，基板を保持する治具等に残留しているＡｌ系残留物と反応して、Ａｌ系残留物を除去することができ、これによって、活性層への酸素の取り込みを抑えることができる。なお、ＨＣｌガスはガスシリンダーに充填して使用することができる。この場合、塩素系ガスによる装置内部の金属部分の腐食を防止するため、酸素，水分等が少ない高純度のものが好ましい。
【０１０９】
第３の実施形態
また、本発明の第３の実施形態の半導体発光素子は、窒素を含む活性層と半導体基板との間にｐ型半導体層を有し、ｐ型半導体層中に配置されたＡｌＡｓを主成分とする被選択酸化層の一部が選択的に酸化されて電流狭窄構造が形成されている半導体発光素子であって、前記被選択酸化層と窒素を含む活性層との間に、少なくとも一層のＧａＩｎＰＡｓ層、または、ＧａＩｎＰ層、または、ＧａＰＡｓ層が形成されていることを特徴としている。
【０１１０】
前述したように、結晶成長途中で、反応室側壁，加熱帯，基板を保持する治具等に残留しているＡｌ系残留物を除去する工程を設けると、被成長基板の表面が酸化やその他のダメージを受け、被成長基板の表面に欠陥が発生する恐れがある。もし、欠陥が発生する場所（領域）がキャリアの注入される活性領域であれば、上記欠陥が非発光再結合中心となり発光素子の動作時に発光効率が低下してしまう恐れがある。
【０１１１】
これに対し、Ａｌ系残留物除去時の表面材料のバンドギャップエネルギーよりも高いバンドギャップエネルギーを有するＧａＩｎＰＡｓ層、または、ＧａＩｎＰ層、または、ＧａＰＡｓ層を、被選択酸化層と窒素を含む活性層との間に成長すると、Ａｌ系残留物除去時の表面への注入キャリアはほとんど無くなるので、欠陥が非発光再結合中心となり発光素子の動作時に発光効率が低下してしまうという事態が生じるのを防止できる。もちろん、ＧａＩｎＰＡｓ層、または、ＧａＩｎＰ層、または、ＧａＰＡｓ層は、Ｂ，Ｔｌ，Ｓｂ等の他のIII−Ｖ族材料を含んでいても良い。
【０１１２】
なお、このような半導体発光素子の結晶成長を行ないながら、窒素化合物原料または窒素化合物原料中に含まれる不純物が触れる場所となるガス供給ライン中もしくは成長室内に残留したＡｌ原料，Ａｌ反応物，Ａｌ化合物，Ａｌのうちの少なくとも１つを有機系窒素化合物ガスで除去する工程を行うことができる。例えば、上記Ａｌを含む半導体層と窒素を含む活性層との間でＡｌを含まない層を成長する時に、エッチングガスであるＤＭＨｙ等の有機系窒素化合物ガスを供給すると、Ａｌと酸素を取りこむ形で窒素を含む半導体層が成長される。これにより、窒素化合物原料または窒素化合物原料中に含まれる不純物が触れる場所となるガス供給ライン中もしくは成長室内に残留したＡｌ原料，Ａｌ反応物，Ａｌ化合物，Ａｌのうちの少なくとも１つを除去できるので、活性層への酸素の取り込みを抑えることができる。この場合、窒素を含む半導体層は、活性層のバンドギャップよりも大きいバンドギャップとなるように条件を設定する必要がある。例えばＤＭＨｙ気相比：［ＤＭＨｙ］／（［ＤＭＨｙ］＋［ＡｓＨ_３］）を小さくし、また、成長温度を高くし、また、Ｉｎ組成を大きくすることにより、窒素の取り込まれは低減する。この窒素を含む半導体層をＳＩＭＳ分析すれば、窒素のほかに酸素（Ｏ）またはＡｌが観察されるであろう。
【０１１３】
第４の実施形態
また、本発明の第４の実施形態の半導体発光素子は、窒素を含む活性層と半導体基板との間にｐ型半導体層を有し、ｐ型半導体層中に配置されたＡｌＡｓを主成分とする被選択酸化層の一部が選択的に酸化されて電流狭窄構造が形成されている半導体発光素子において、前記被選択酸化層と窒素を含む活性層との間に、活性層よりもバンドギャップが大きくかつ窒素を含む半導体層が形成されていることを特徴としている。
【０１１４】
なお、このような半導体発光素子の結晶成長を行ないながら、窒素化合物原料または窒素化合物原料中に含まれる不純物が触れる場所となるガス供給ライン中もしくは成長室内に残留したＡｌ原料，Ａｌ反応物，Ａｌ化合物，Ａｌのうちの少なくとも１つを有機系窒素化合物ガスで除去する工程を行うことができる。例えば、上記Ａｌを含む半導体層と窒素を含む活性層との間でＡｌを含まない層を成長する時に、エッチングガスであるＤＭＨｙ等の有機系窒素化合物ガスを供給すると、Ａｌと酸素を取りこむ形で窒素を含む半導体層が成長される。これにより、窒素化合物原料または窒素化合物原料中に含まれる不純物が触れる場所となるガス供給ライン中もしくは成長室内に残留したＡｌ原料，Ａｌ反応物，Ａｌ化合物，Ａｌのうちの少なくとも１つを除去できるので、活性層への酸素の取り込みを抑えることができる。この場合、窒素を含む半導体層は、活性層のバンドギャップよりも大きいバンドギャップとなるように条件を設定する必要がある。例えばＤＭＨｙ気相比：［ＤＭＨｙ］／（［ＤＭＨｙ］＋［ＡｓＨ_３］）を小さくし、また、成長温度を高くし、また、Ｉｎ組成を大きくすることにより、窒素の取り込まれは低減する。この窒素を含む半導体層をＳＩＭＳ分析すれば、窒素のほかに酸素（Ｏ）またはＡｌが観察されるであろう。
【０１１５】
上記第４の実施形態の半導体発光素子において、活性層よりもバンドギャップが大きくかつ窒素を含む半導体層として、ＧａＮＡｓ，ＧａＩｎＮＡｓ，ＧａＩｎＮＰ，ＧａＮＰＡｓ，ＧａＩｎＮＰＡｓなどを用いることができる。もちろん、Ｓｂ，Ｂ，Ｔｌ等の他のＩＩＩ−Ｖ族材料を含んでいてもかまわない。
【０１１６】
また、上記第４の実施形態の半導体発光素子において、活性層よりもバンドギャップが大きくかつ窒素を含む半導体層と窒素を含む活性層との間に、その両者よりもバンドギャップエネルギーが大きいＧａＡｓ，ＧａＩｎＡｓ，ＧａＡｓＰ，ＧａＩｎＰＡｓ，ＧａＩｎＰのいずれか一つからなる層が形成されていても良い。
【０１１７】
すなわち、活性層よりもバンドギャップが大きくかつ窒素を含む半導体層中には酸素が取りこまれてしまうので、もしこの層がキャリアの注入される活性領域内にあれば、非発光再結合中心となり発光素子動作時発光効率を低下させてしまう恐れがある。これに対し、Ａｌ系残留物除去時の表面材料のバンドギャップエネルギーよりも高いバンドギャップエネルギーを有するＧａＡｓ，ＧａＩｎＡｓ，ＧａＩｎＰＡｓ，ＧａＩｎＰ，ＧａＰＡｓのいずれか一つからなる層を窒素を含む活性層との間に成長すると、活性層よりもバンドギャップが大きくかつ窒素を含む半導体層への注入キャリアはほとんど無くなるので、上記の原因によって発光効率が低下してしまうことは無くなる。
【０１１８】
第５の実施形態
本発明の第５の実施形態の面発光型半導体レーザ素子の製造方法は、窒素を含む活性層を有する活性領域と、レーザ光を得るために活性層の上部および下部に設けられた上部反射鏡および下部反射鏡とを含む共振器構造を備え、窒素を含む活性層と半導体基板との間にｐ型半導体層を有している面発光型半導体レーザ素子の製造方法であって、前記下部反射鏡は、屈折率が周期的に変化し入射光を光波干渉によって反射する半導体分布ブラッグ反射鏡を含み、該半導体分布ブラッグ反射鏡の屈折率が小さい層はＡｌ_ｘＧａ_{1- ｘ}Ａｓ（０＜ｘ≦１）からなり、また、該半導体分布ブラッグ反射鏡の屈折率が大きい層はＡｌ_ｙＧａ_{1- ｙ}Ａｓ（０≦ｙ＜ｘ≦１）からなり、前記ｐ型半導体層の一部を選択的に酸化して電流狭窄を行うためのＡｌＡｓを主成分とする被選択酸化層を有し、被選択酸化層と窒素を含む活性層との間に、少なくとも１層のＧａＩｎＰＡｓ層、または、ＧａＩｎＰ層、または、ＧａＰＡｓ層を形成し、前記被選択酸化層の成長後、前記ＧａＩｎＰＡｓ層、または、ＧａＩｎＰ層、または、ＧａＰＡｓ層の成長が完了するまでの間に、窒素化合物原料または窒素化合物原料中に含まれる不純物が触れる場所となるガス供給ライン中もしくは成長室内に残留したＡｌ原料，Ａｌ反応物，Ａｌ化合物，Ａｌのうちの少なくとも１つを除去する工程を設けることを特徴としている。
【０１１９】
面発光型半導体レーザ素子の活性層への酸素の取りこまれを抑制する具体的方法の一つとしては、被選択酸化層の成長後、ＧａＩｎＰＡｓ層、または、ＧａＩｎＰ層、または、ＧａＰＡｓ層の成長が完了するまでの間に成長中断して、ガス供給ラインもしくは成長室内に残留したＡｌ原料，Ａｌ反応物，Ａｌ化合物，Ａｌのうちの少なくとも１つを除去する工程を行うことである。これにより、窒素を含む活性層への酸素の取りこまれが抑制され、かつ成長中断して形成された欠陥による非発光再結合の影響が避けられるので、低抵抗で駆動電圧が低く、しかも発光効率が高く低しきい値電流動作し、温度特性が良い面発光型半導体レーザ素子を容易に低コストで実現できる。なお、成長中断しているので、この成長中断界面をＳＩＭＳ分析すれば、酸素（Ｏ）が観察されるであろう。
【０１２０】
また、上記成長中断中に、サセプターをベーキングするようにすることができる。
【０１２１】
すなわち、サセプターを加熱することで、反応室側壁，加熱帯，基板を保持する治具等に残留しているＡｌ系残留物が蒸発，反応しやすくなるので、除去する効果が高くなる。また、結晶成長はサセプターを加熱して行われるので、成長中断して同様に加熱すれば良く、従って、成長中断中のサセプターのベーキングは容易にできる。なお、このとき、ベーキング温度は、結晶成長時の温度よりも高くするのが好ましい。また、被成長基板は、別室に移動しても良く、別室に移動せずにそのまま行っても良い。そのまま行う場合は、Ｖ族元素が成長途中の被成長基板から蒸発，脱離しないようにするために、Ｖ族原料を供給して行うのが望ましい。
【０１２２】
第６の実施形態
また、本発明の第６の実施形態の面発光型半導体レーザ素子は、窒素を含む活性層を有する活性領域と、レーザ光を得るために活性層の上部および下部に設けられた上部反射鏡および下部反射鏡とを含む共振器構造を備え、窒素を含む活性層と半導体基板との間にｐ型半導体層を有している面発光型半導体レーザ素子であって、前記下部反射鏡は、屈折率が周期的に変化し入射光を光波干渉によって反射する半導体分布ブラッグ反射鏡を含み、該半導体分布ブラッグ反射鏡の屈折率が小さい層はＡｌ_ｘＧａ_{1- ｘ}Ａｓ（０＜ｘ≦１）からなり、また、該半導体分布ブラッグ反射鏡の屈折率が大きい層はＡｌ_ｙＧａ_{1- ｙ}Ａｓ（０≦ｙ＜ｘ≦１）からなり、前記ｐ型半導体層の一部を選択的に酸化して電流狭窄を行うためのＡｌＡｓを主成分とする被選択酸化層を有し、被選択酸化層と窒素を含む活性層との間に、少なくとも１層のＧａＩｎＰＡｓ層、または、ＧａＩｎＰ層、または、ＧａＰＡｓ層が形成されていることを特徴としている。
【０１２３】
ここで、窒素を含む活性層には、ＧａＮＡｓ，ＧａＩｎＮＡｓ，ＩｎＮＡｓ，ＧａＡｓＮＳｂ，ＧａＩｎＮＡｓＳｂ，ＧａＮＰＡｓ ，ＧａＩｎＮＰＡｓ ，ＩｎＮＰＡｓ ，ＧａＡｓＮＰＳｂ ，ＧａＩｎＮＰＡｓＳｂ等を用いることができる。例えばＧａＩｎＮＡｓを用いる場合について以下に説明する。ＧａＩｎＮＡｓは、ＧａＡｓよりも格子定数が大きいＧａＩｎＡｓにＮを添加することで、ＧａＡｓに格子整合させることが可能になるとともに、そのバンドギャップが小さくなり、１．３μｍ，１．５５μｍ帯での発光が可能となる。また、ＧａＡｓ基板格子整合系なので、ワイドギャップのＡｌＧａＡｓやＧａＩｎＰをクラッド層に用いることができる。
【０１２４】
さらに、Ｎの添加により上記のようにバンドギャップが小さくなるとともに、伝導帯，価電子帯のエネルギーレベルがともに下がり、ヘテロ接合における伝導帯のバンド不連続が極めて大きくなる結果、レーザの動作電流の温度依存性を極めて小さくできる。
【０１２５】
さらに、面発光型半導体レーザ素子は、小型化、低消費電力化及び２次元集積化による並列伝送を行なうのに有利である。面発光型半導体レーザ素子は、従来のＧａＩｎＰＡｓ／ＩｎＰ系では実用化に耐え得る性能を得るのは困難であるが、ＧａＩｎＮＡｓ系材料によるとＧａＡｓ基板を用いた０．８５μｍ帯面発光型半導体レーザ素子などで実績のあるＡｌ（Ｇａ）Ａｓ／（Ａｌ）ＧａＡｓ系半導体多層膜分布ブラッグ反射鏡や、ＡｌＡｓの選択酸化による電流狭さく構造が適用できるので、実用化が期待できる。
【０１２６】
これを実現するためには、ＧａＩｎＮＡｓ活性層の結晶品質の向上や、多層膜反射鏡の低抵抗化、面発光型半導体レーザ素子としての多層膜構造体の結晶品質や制御性の向上が重要であったが、ＡｌＡｓを主成分とした被選択酸化層と窒素を含む活性層との間に、少なくとも一層のＧａＩｎＰＡｓ層、または、ＧａＩｎＰ層、または、ＧａＰＡｓ層を形成することで、本発明の製造方法を容易に適用でき、窒素を含む活性層への酸素の取りこまれが抑制され、低抵抗で駆動電圧が低く、しかも発光効率が高く低しきい値電流動作し、温度特性が良い面発光型半導体レーザ素子を容易に低コストで実現できる。更に、この面発光型半導体レーザ素子の構成によれば、ｐ型基板を用いることが可能である。
【０１２７】
第７の実施形態
また、本発明の第７の実施形態の面発光型半導体レーザ素子は、窒素を含む活性層を有する活性領域と、レーザ光を得るために活性層の上部および下部に設けられた上部反射鏡および下部反射鏡とを含む共振器構造を備え、窒素を含む活性層と半導体基板との間にｐ型半導体層を有している面発光型半導体レーザ素子であって、前記下部反射鏡は、屈折率が周期的に変化し入射光を光波干渉によって反射する半導体分布ブラッグ反射鏡を含み、該半導体分布ブラッグ反射鏡の屈折率が小さい層はＡｌ_ｘＧａ_{1- ｘ}Ａｓ（０＜ｘ≦１）からなり、また、該半導体分布ブラッグ反射鏡の屈折率が大きい層はＡｌ_ｙＧａ_{1- ｙ}Ａｓ（０≦ｙ＜ｘ≦１）からなり、前記ｐ型半導体層の一部を選択的に酸化して電流狭窄を行うためのＡｌＡｓを主成分とする被選択酸化層を有し、被選択酸化層と窒素を含む活性層との間に、活性層よりもバンドギャップが大きくかつ窒素を含む半導体層が形成されていることを特徴としている。
【０１２８】
例えば、上記Ａｌを含む半導体層と窒素を含む活性層との間でＡｌを含まない層を成長する時に、エッチングガスであるＤＭＨｙ等の有機系窒素化合物ガスを供給すると、Ａｌと酸素を取りこむ形で窒素を含む半導体層が成長される。これにより、成長室内に残留したＡｌ原料，Ａｌ反応物，Ａｌ化合物，Ａｌのうちの少なくとも１つを除去できるので、活性層への酸素の取り込みを抑えることができる。この場合、窒素を含む半導体層は、活性層のバンドギャップよりも大きいバンドギャップとなるように条件を設定する必要がある。例えばＤＭＨｙ気相比：［ＤＭＨｙ］／（［ＤＭＨｙ］＋［ＡｓＨ_３］）を小さくし、また、成長温度を高くし、また、Ｉｎ組成を大きくすることにより、窒素の取り込まれは低減する。この窒素を含む半導体層をＳＩＭＳ分析すれば、窒素のほかに酸素（Ｏ）またはＡｌが観察されるであろう。
【０１２９】
これにより、窒素を含む活性層への酸素の取りこまれが抑制され、かつ成長中断して形成された欠陥による非発光再結合の影響が避けられるので、低抵抗で駆動電圧が低く、しかも発光効率が高く低しきい値電流動作し、温度特性が良い面発光型半導体レーザ素子を容易に低コストで実現できる。更に、この面発光型半導体レーザ素子の構成によれば、ｐ型基板を用いることが可能となる。
【０１３０】
上記第７の実施形態の面発光型半導体レーザ素子において、活性層よりもバンドギャップが大きくかつ窒素を含む半導体層として、ＧａＮＡｓ，ＧａＩｎＮＡｓ，ＧａＩｎＮＰ，ＧａＮＰＡｓ、ＧａＩｎＮＰＡｓなどを用いることができる。もちろん、Ｓｂ，Ｂ，Ｔｌ等の他のＩＩＩ−Ｖ族材料を含んでいてもかまわない。
【０１３１】
また、上記第７の実施形態の面発光型半導体レーザ素子において、活性層よりもバンドギャップが大きくかつ窒素を含む半導体層と窒素を含む活性層との間に、その両者よりもバンドギャップエネルギーが大きいＧａＡｓ，ＧａＩｎＡｓ，ＧａＡｓＰ，ＧａＩｎＰＡｓ，ＧａＩｎＰのいずれか１つからなる層が形成されていても良い。
【０１３２】
すなわち、活性層よりもバンドギャップが大きくかつ窒素を含む半導体層中には酸素が取りこまれてしまうので、もしこの層がキャリアの注入される活性領域内にあれば、非発光再結合中心となり発光素子動作時発光効率を低下させてしまう恐れがある。これに対し、Ａｌ系残留物除去時の表面材料のバンドギャップエネルギーよりも高いバンドギャップエネルギーを有するＧａＡｓ，ＧａＩｎＡｓ，ＧａＩｎＰＡｓ，ＧａＩｎＰ，ＧａＰＡｓのいずれか１つからなる層を窒素を含む活性層との間に成長すると、活性層よりもバンドギャップが大きくかつ窒素を含む半導体層への注入キャリアはほとんど無くなるので、上記の原因によって発光効率が低下してしまうことは無くなる。
【０１３３】
第８の実施形態
本発明の第８の実施形態の面発光型半導体レーザアレイは、第６または第７の実施形態の面発光型半導体レーザ素子が複数個配列されて構成されていることを特徴としている。
【０１３４】
第６または第７の実施形態の面発光型半導体レーザ素子によれば、ｐ側を共通電極とすることができ、アノードコモンとすることができるので、高速動作が可能なバイポーラトランジスタ駆動回路を用いることができて、複数の素子をアレイにすることで、同時により多くのデータを伝送することが可能となる。
【０１３５】
第９の実施形態
本発明の第９の実施形態の光送信モジュールは、第６または第７の実施形態の面発光型半導体レーザ素子、または、第８の実施形態の面発光型半導体レーザアレイが光源として用いられていることを特徴としている。
【０１３６】
上述したような低抵抗で駆動電圧が低く、低しきい値電流動作し、温度特性が良い第６または第７の実施形態の面発光型半導体レーザ素子、または、第８の実施形態の面発光型半導体レーザアレイを用いることによって、冷却素子が不要な低コストな光送信モジュールを実現することができる。
【０１３７】
第１０の実施形態
本発明の第１０の実施形態の光送受信モジュールは、第６または第７の実施形態のいずれかの面発光型半導体レーザ素子、または、第８の実施形態の面発光型半導体レーザアレイが光源として用いられていることを特徴としている。
【０１３８】
上述したような低抵抗で駆動電圧が低く、低しきい値電流動作し、温度特性が良い第６または第７の実施形態の面発光型半導体レーザ素子、または、第８の実施形態の面発光型半導体レーザアレイを用いることによって、冷却素子が不要な低コストな光送受信モジュールを実現することができる。
【０１３９】
第１１の実施形態
本発明の第１１の実施形態の光通信システムは、第６または第７の実施形態の面発光型半導体レーザ素子、または、第８の実施形態の面発光型半導体レーザアレイが光源として用いられていることを特徴としている。
【０１４０】
上述したような低抵抗で駆動電圧が低く、低しきい値電流動作し、温度特性が良い第６または第７の実施形態の面発光型半導体レーザ素子、または、第８の実施形態の面発光型半導体レーザアレイを用いることによって、冷却素子が不要な低コストの光ファイバー通信システム，光インターコネクションシステムなどの光通信システムを実現することができる。
【０１４１】
第１２の実施形態
本発明の第１２の実施形態の半導体発光素子の製造方法は、基板と窒素を含む活性層との間にＡｌを含む半導体層が設けられる半導体発光素子の製造方法において、Ａｌを含む半導体層を成長した後であって、窒素を含む活性層の成長を開始する前に、エッチングガスとしてＣＢｒ_４等の臭素を含んだガスを成長室（反応室）内に供給し、成長室内に残留したＡｌ原料，Ａｌ反応物，Ａｌ化合物，Ａｌのうちの少なくとも１つを除去する工程を設けたことを特徴としている。
【０１４２】
前述したように、Ａｌ系残留物は、非発光再結合の原因となる酸素を、窒素を含む活性層に取りこむ原因となっているので、Ａｌを含んだ半導体層を成長した後、窒素を含む活性層の成長の前までに、反応室（成長室）側壁，加熱帯，基板を保持する治具等に残留しているＡｌ系残留物と反応してＡｌ系残留物を除去することのできるガスを成長室に供給することで、活性層への酸素の取り込みを抑えることができる。ＣＢｒ_４のような臭素を含んだガスは、成長室内の反応生成堆積物と反応し、エッチング除去する効果がある。よって、Ａｌを含んだ半導体層を成長した後、窒素を含む活性層の成長の前までに、エッチングガスとして臭素を含んだガスを供給すると、このエッチングガスは反応室側壁，加熱帯，基板を保持する治具等に残留しているＡｌ系残留物と反応してＡｌ系残留物を除去することができるので、活性層への酸素の取り込みを抑えることができる。
【０１４３】
また、臭素を含んだガスは、ＧａＡｓなどの半導体層をエッチングする効果がある。成長を一度中断して、成長室内に残留したＡｌ原料，Ａｌ反応物，Ａｌ化合物，Ａｌのうちの少なくとも１つを除去する場合、エピ基板表面は酸化膜等が形成される可能性がある。従って、成長を一度中断した後、再成長する前に、エッチングガスとして臭素を含んだガスを成長室内に供給し、被成長基板の表面の一部を除去する工程を設けると、酸化膜等を除去できるので、再成長界面での非発光再結合などの素子特性への悪影響を抑えられる。すなわち、基板と活性層との間にＡｌを含む半導体層が設けられる半導体発光素子の製造方法であって、前記Ａｌを含む半導体層を成長した後であって、窒素を含む活性層の成長を開始する前に成長を一度中断し、再成長する前にエッチングガスとして臭素を含んだガスを成長室内に供給し、被成長基板の表面の一部を除去する工程を設けるのが良い。なお、形成する素子が面発光型半導体レーザの場合、厚さの制御が重要なので、エッチング深さを予想してあらかじめエッチングする分を厚く成長しておくか、再成長時にエッチングする分を厚く成長する必要がある。また、臭素を含んだガスとして、ＣＢｒ_４以外にも、ＣＨ_３Ｂｒ等のガスを用いることができる。また、ＨＣｌ等の塩素を含んだガスを用いてもＧａＡｓなどの半導体層をエッチングできるので、同様な効果を得ることができる。
【０１４４】
【実施例】
以下、本発明の実施例について説明する。
【０１４５】
（第１の実施例）
図７（ａ），（ｂ）は本発明の第１の実施例のＧａＩｎＮＡｓ面発光型半導体レーザ素子を示す図である。なお、図７（ｂ）は、図７（ａ）の部分拡大図である。
【０１４６】
図７（ａ），（ｂ）に示すように、この第１の実施例の面発光型半導体レーザ素子では、２インチの大きさの面方位（１００）のｐ−ＧａＡｓ基板上に、それぞれの媒質内における発振波長λの１／４倍の厚さでｐ−Ａｌ_ｘＧａ_１−ｘＡｓ（ｘ＝０．９）とｐ−ＧａＡｓとを交互に３５周期積層した周期構造からなるｐ−半導体分布ブラッグ反射鏡（下部半導体分布ブラッグ反射鏡：単に下部反射鏡ともいう）が形成されている。なお、この下部反射鏡の最上部の低屈折率層は、被選択酸化層となるＡｌＡｓをＡｌＧａＡｓ及びＧａＩｎＰで挟んだ３λ／４の厚さの低屈折率層からなっている。ここで、ＡｌＡｓは、厚さを３０ｎｍとして、下から２λ／４の位置に来るようにしている。また、ｐ−ＡｌＡｓ被選択酸化層とｐ−ＧａＩｎＰの間には、４０ｎｍの厚さのＧａＡｓ層が挿入されている。
【０１４７】
そして、この第１の実施例の面発光型半導体レーザ素子では、下部反射鏡上に、アンドープ下部ＧａＡｓスペーサ層，３層のＧａ_ｘＩｎ_１−ｘＮ_ｙＡｓ_１−ｙ（ｘ、ｙ）井戸層とＧａＡｓバリア層からなる多重量子井戸活性層，アンドープ上部ＧａＡｓスペーサ層が形成されている。
【０１４８】
そして、その上にｎ−半導体分布ブラッグ反射鏡（上部半導体分布ブラッグ反射鏡：単に上部反射鏡ともいう）が形成されている。ここで、上部反射鏡は、Ｓｉドープのｎ−Ａｌ_ｘＧａ_１−ｘＡｓ（ｘ＝０．９）とｎ−ＧａＡｓとをそれぞれの媒質内における発振波長の１／４倍の厚さで交互に積層した周期構造（例えば、２５周期）から構成されている。上部反射鏡と下部反射鏡とにより挟まれた共振器領域の厚さは、ＧａＡｓスペーサ層と多重量子井戸活性層とで、１波長分の厚さとした。
【０１４９】
また、上部反射鏡の最上部のｎ−ＧａＡｓ層は、ｎ側電極とコンタクトを取るｎ−ＧａＡｓコンタクト層を兼ねている。また、活性層内の井戸層のＩｎ組成ｘは３７％，窒素組成は０．５％とした。また、井戸層の厚さは７ｎｍとした。また、活性層は、ＧａＡｓ基板に対して約２．５％の圧縮歪（高歪）を有していた。
【０１５０】
次いで、所定の大きさのメサを少なくともｐ−ＡｌＡｓ被選択酸化層の側面を露出させて形成し、側面の現れたＡｌＡｓを水蒸気で側面から酸化してＡｌ_ｘＯ_ｙ電流狭さく部を形成した。そして、次に、ポリイミドでエッチング部を埋め込んで平坦化し、ｎ−ＧａＡｓコンタクト層上のポリイミドを除去し、ｎ−ＧａＡｓコンタクト層上の光出射部以外にｎ側電極を形成し、また、基板の裏面にｐ側電極を形成した。
【０１５１】
このような面発光型半導体レーザ素子は、ＭＯＣＶＤ法によって形成することができ、この場合、ＭＯＣＶＤ法によるＧａＩｎＮＡｓ活性層の原料には、ＴＭＧ（トリメチルガリウム），ＴＭＩ（トリメチルインジウム），ＡｓＨ_３（アルシン）を用いることができ、また、窒素の原料にはＤＭＨｙ（ジメチルヒドラジン）を用いることができる。また、キャリアガスにはＨ_２を用いることができる。ここで、ＤＭＨｙは低温で分解するので、６００℃以下のような低温成長に適しており，特に低温成長の必要な歪みの大きい量子井戸層を成長する場合、好ましい原料である。また、この第１の実施例のＧａＩｎＮＡｓ面発光型半導体レーザ素子の活性層のように歪が大きい場合は、非平衡となる低温成長が好ましい。この第１の実施例では、ＧａＩｎＮＡｓ層は５４０℃で成長させた。
【０１５２】
ところで、この第１の実施例では、活性層への酸素の取り込みを抑え発光効率を低下させないようにするため、下部反射鏡の最上部の低屈折率層中に設けたＧａＡｓ層（４０ｎｍの厚さ）の成長の途中で成長中断し、一度被成長基板を別室に移動させ、被成長基板を保持していたサセプターを成長室に戻してキャリアガスであるＨ_２ガスを供給しながらサセプターを成長温度より高い温度で加熱させ、Ａｌ系残留物を除外した。このとき、サセプター以外の成長室内壁等の温度も上昇し、Ａｌ系残留物の除外が加速される。これにより、活性層への酸素の取り込みを抑えることができた。この工程は、Ａｌを含んだ半導体層の成長後、窒素を含んだ活性層の成長の前までに行えば良い。望ましくは、この第１の実施例のように、成長中断した界面（この第１の実施例では、ＧａＡｓ層）のバンドギャップよりも大きいバンドギャップを有しＡｌを含まない材料（この第１の実施例ではＧａＩｎＰ）を、窒素を含む活性層との間に形成すると良い。
【０１５３】
すなわち、結晶成長を中断して、反応室側壁，加熱帯，基板を保持する治具等に残留しているＡｌ系残留物を除去する工程を設けることで、被成長基板の表面が酸化やその他のダメージを受けて欠陥が発生する恐れがある。もしこの場所（領域）がキャリアの注入される活性領域であれば、発生した欠陥が非発光再結合中心となり発光素子動作時発光効率が低下してしまう。
【０１５４】
これに対し、この第１の実施例のように、Ａｌ系残留物除去時の表面材料のバンドギャップエネルギーよりも高いバンドギャップエネルギーを有するＧａＩｎＰＡｓ層、または、ＧａＩｎＰ層、または、ＧａＰＡｓ層を、窒素を含む活性層との間に成長すると、素子動作時にＡｌ系残留物除去時の表面への注入キャリアがほとんど無くなるので、これが原因で発光効率が低下することは無くなり、高い発光効率での動作が可能となる。
【０１５５】
なお、この第１の実施例では、Ａｌ系残留物除去工程は、１台の結晶成長装置を用いて結晶成長するときに、結晶成長を中断して行っているが、Ａｌ系材料成長装置と窒素を含む活性層を成長する装置とを別々に用い組み合わせて結晶成長するときにも、結晶成長を中断してＡｌ系残留物除去工程を行なうことができる。すなわち、窒素を含む活性層を成長する時に、装置内のＡｌ系残留物が酸素とともに活性層に取りこまれないようにすれば良い。
【０１５６】
上述したように作製した面発光型半導体レーザ素子の発振波長は約１．３μｍであった。この第１の実施例では、ＧａＩｎＮＡｓを活性層に用いたので、ＧａＡｓ基板上に長波長帯の面発光型半導体レーザ素子を形成できた。また、この第１の実施例では、装置内に残留したＡｌを含む化合物が、窒素を含む活性層の成長時に酸素とともに膜中に取りこまれないように、残留したＡｌを含む化合物を除外したので、活性層に酸素がＡｌとともに混入することを抑えることができた。これにより、発光効率が高く低しきい値で発振するＧａＩｎＮＡｓ面発光型半導体レーザ素子を量産に有利なＭＯＣＶＤ法で製造できた。
【０１５７】
また、ＡｌとＡｓを主成分とした被選択酸化層の選択酸化により電流狭さく層を形成したので、しきい値電流は低かった。被選択酸化層を選択酸化したＡｌ酸化膜からなる電流狭さく層を用いた電流狭さく構造によると、電流狭さく層を活性層に近づけて形成することで、電流の広がりを抑えられ、大気に触れない微小領域に効率良くキャリアを閉じ込めることができる。さらに、酸化してＡｌ酸化膜となることで、屈折率が小さくなり、凸レンズの効果でキャリアの閉じ込められた微小領域に効率良く光を閉じ込めることができ、極めて効率が良くなり、しきい値電流を低減することができる。また、容易に電流狭さく構造を形成できることから、製造コストを低減できる。
【０１５８】
なお、窒素と他のＶ族を含んだＧａＩｎＮＡｓ等の半導体層の成長法としては、ＭＢＥ法が主に用いられていたが、ＭＢＥ法は原理的に高真空中での成長なので、原料供給量を大きくできない。原料供給量を大きくすると、排気系に負担がかかるという欠点がある。また、ＭＢＥ法は、高真空排気系の排気ポンプを必要とするが、ＭＢＥチャンバー内の残留原料等を除去するなどのために、排気系に負担がかかり故障しやすいことから、スループットは悪い。
【０１５９】
また、面発光型半導体レーザ素子は、レーザ光を発生する少なくとも１層の活性層を含んだ活性領域を半導体多層膜反射鏡で挟んで構成されている。端面発光型レーザの結晶成長層の厚さが３μｍ程度であるのに対して、例えば１．３μｍ波長帯の面発光型半導体レーザ素子では１０μｍを超える厚さが必要になるが、ＭＢＥ法では高真空を必要とすることから、原料供給量を高くすることができず、成長速度は１μｍ／ｈ程度であり、１０μｍの厚さを成長するには、原料供給量を変えるための成長中断時間を設けないとしても最低１０時間かかる。
【０１６０】
ここで、活性領域の厚さは全体に比べて通常ごくわずかであり（１０％以下）、ほとんどが多層膜反射鏡を構成する層である。半導体多層膜反射鏡は、それぞれの媒質内における発振波長の１／４倍の厚さ（λ／４の厚さ）で低屈折率層と高屈折率層を交互に積層して（例えば２０〜４０ペア）形成されている。ＧａＡｓ基板上の面発光型半導体レーザ素子では、半導体多層膜反射鏡は、ＡｌＧａＡｓ系材料を用いＡｌ組成を変えて低屈折率層（Ａｌ組成大）と高屈折率層（Ａｌ組成小）としている。しかし実際には、特にｐ側は各層のヘテロ障壁により抵抗が大きくなるので、低屈折率層と高屈折率層の間に、Ａｌ組成が両者の間となる中間層を挿入して多層膜反射鏡の抵抗を低減している。
【０１６１】
このように、面発光型半導体レーザ素子は、１００層を超える組成の異なる半導体層を成長しなければならないことの他に、多層膜反射鏡の低屈折率層と高屈折率層の間にも中間層を設けるなど、瞬時に原料供給量を制御する必要がある素子である。しかし、ＭＢＥ法では、原料供給を原料セルの温度を変えて供給量を制御しており、臨機応変に組成をコントロールすることができない。よってＭＢＥ法により成長した半導体多層膜反射鏡では、その抵抗を低くするのは困難であり動作電圧が高くなってしまう。
【０１６２】
一方、ＭＯＣＶＤ法は、原料ガス流量を制御するだけでよく、瞬時に組成をコントロールできるとともに、ＭＢＥ法のような高真空を必要とせず、また成長速度を例えば３μｍ／ｈ以上と高くでき、容易にスループットを上げられることから、極めて量産に適した成長方法である。
【０１６３】
このように第１の実施例によれば、ＭＯＣＶＤ法を用いて、低消費電力で低コストの１．３μｍ帯の面発光型半導体レーザ素子を実現できた。
【０１６４】
（第２の実施例）
図８（ａ），（ｂ）は本発明の第２の実施例のＧａＩｎＮＡｓ面発光型半導体レーザ素子を示す図である。なお、図８（ｂ）は、図８（ａ）の部分拡大図である。この第２の実施例が第１の実施例と違うところは、成長室内に残留したＡｌ原料，Ａｌ反応物，Ａｌ化合物，Ａｌのうちの少なくとも１つを除去する工程を、多層膜反射鏡内ではなく、共振器内部で行っている点である。これによって、窒素を含む活性層への酸素の混入が抑制され、発光効率を高めることができた。
【０１６５】
ただし、この第２の実施例では、成長室内に残留したＡｌ原料，Ａｌ反応物，Ａｌ化合物，Ａｌのうちの少なくとも１つを除去する工程を、多層膜反射鏡内ではなく、共振器内部で行なうことによって、被成長基板の表面が、酸化やその他のダメージを受けて、欠陥が発生する恐れがあり、この場所（領域）がキャリアの注入される活性領域であれば、発生した欠陥は非発光再結合中心となり、発光素子動作時発光効率が低下してしまう恐れがあるので、Ａｌ系残留物除去時の表面材料（この第２の実施例では、成長中断界面であるＧａＡｓ）のバンドギャップエネルギーよりも高いバンドギャップエネルギーを有するＧａＰＡｓ層を窒素を含む活性層との間に設けている。なお、この第２の実施例の活性層は２％を超える大きな圧縮歪を有しており、ＧａＰＡｓはＧａＡｓ基板に対して引張り歪を有していることから、ＧａＰＡｓは、歪の悪影響を和らげるという効果もある。このため、この第２の実施例では、活性層の上部にも、ＧａＰＡｓ層を設けている。
【０１６６】
上述の例では、ＧａＰＡｓ層を設けたが、ＧａＰＡｓ層のかわりに、ＧａＩｎＰＡｓ層、または、ＧａＩｎＰ層を設けることもできる。
【０１６７】
これにより、素子動作時にＡｌ系残留物除去時の表面への注入キャリアはほとんど無くなるので、発光効率が低下することは無くなり、高い発光効率で、低しきい値で発振するＧａＩｎＮＡｓ面発光型半導体レーザ素子を、量産に有利なＭＯＣＶＤ法で製造できた。
【０１６８】
（第３の実施例）
図９は本発明の第３の実施例のＧａＩｎＮＡｓ面発光型半導体レーザ素子を示す図である。
【０１６９】
この第３の実施例が第２の実施例と違うところは、成長室内に残留したＡｌ原料，Ａｌ反応物，Ａｌ化合物，Ａｌのうちの少なくとも１つを除去する工程は、ＧａＡｓ下部スペーサ層の成長途中で、ＤＭＨｙを供給してＧａＮＡｓ層を成長することによって行なわれる。このＧａＮＡｓ層は、ＧａＩｎＮＡｓ活性層よりバンドギャップエネルギーが大きい条件となっている。
【０１７０】
第３の実施例により作製した面発光型半導体レーザ素子の発振波長は約１．３μｍであった。また、第３の実施例では、ＧａＩｎＮＡｓを活性層に用いているので、ＧａＡｓ基板上に長波長帯の面発光型半導体レーザ素子を形成できた。
【０１７１】
また、第３の実施例では、装置内に残留したＡｌを含む化合物が、窒素を含む活性層の成長時に酸素とともに活性層中に取りこまれないように、エッチングガスであるＤＭＨｙを供給してＧａＮＡｓ層を成長しているので、除去工程を行ったＧａＮＡｓ層に酸素とともにＡｌが取りこまれたが、反応室内に残留したＡｌを含んだ化合物は活性層の成長前に除外され、活性層に酸素がＡｌとともに混入することを抑えることができる。すなわち、この除去工程を行ったＧａＮＡｓ層は、活性層のダミー層といえる。これにより、第３の実施例では、発光効率が高く低しきい値で発振するＧａＩｎＮＡｓ面発光型半導体レーザ素子を量産に有利なＭＯＣＶＤ法で製造できた。
【０１７２】
（第４の実施例）
図１０は本発明の第４の実施例のＧａＩｎＮＡｓ面発光型半導体レーザアレイ（ＧａＩｎＮＡｓ面発光型半導体レーザアレイチップ）を示す図である。
【０１７３】
この第４の実施例のＧａＩｎＮＡｓ面発光型半導体レーザアレイは、第１の実施例の面発光半導体レーザ素子が１０個、１次元に並んだものとなっている。なお、第４の実施例のＧａＩｎＮＡｓ面発光型半導体レーザアレイとしては、第１の実施例の面発光半導体レーザ素子を２次元に集積させたものでも良い。なお、この第４の実施例のＧａＩｎＮＡｓ面発光型半導体レーザアレイは、ｐ型ＧａＡｓ半導体基板上に形成されており、上面にｎ側個別電極が形成され、基板の裏面にｐ側共通電極が形成されている。
【０１７４】
この第４の実施例では、ｐ側共通電極となるような構成でしかも高性能化に向いている選択酸化構造を用いた長波長帯の面発光型半導体レーザアレイを、量産性に優れたＭＯＣＶＤ法で作製可能となった。
【０１７５】
なお、この第４の実施例では、ｐ型基板を用いたが、半絶縁性基板上に、ｐ側、活性層、ｎ側の順番で結晶成長を行なうこともでき、この場合も同様に、ｐ側共通電極の構造が形成可能である。なお、この場合、共通電極は裏面ではなく、ｎ側と同じ側に形成することになる。
【０１７６】
（第５の実施例）
図１１は本発明の第５の実施例の光送信モジュールを示す図であり、この第５の実施例の光送信モジュールは、第４の実施例の面発光型半導体レーザアレイチップと光ファイバーとを組み合わせたものとなっている。この第５の実施例の光送信モジュールでは、１．３μｍ帯ＧａＩｎＮＡｓの面発光型半導体レーザ素子からのレーザ光を石英系光ファイバーに入力させて、光伝送を行なうことができる。ここで、波長が光ファイバー通信に適した１．３μｍであり、シングルモードファイバーを使うことができた。
【０１７７】
また、この第５の実施例では、第４の実施例のＧａＩｎＮＡｓ面発光型半導体レーザアレイを用いており、ｐ側が共通となったので、高速動作が可能なバイポーラトランジスタ駆動回路を採用できた。これにより、高速な並列伝送が可能となり、従来よりも多くのデータを同時に伝送できるようになった。
【０１７８】
なお、この第５の実施例では、面発光型半導体レーザ素子と光ファイバーとを１対１に対応させたが、発振波長の異なる複数の面発光型半導体レーザ素子を１次元または２次元にアレイ状に配置して、波長多重送信することにより伝送速度を更に増大することが可能となる。
【０１７９】
さらに、本発明による面発光型半導体レーザ素子を光通信システムに用いると、低コストで信頼性が高い光送信モジュールを実現できる他、これを用いた低コスト，高信頼の光通信システムを実現できる。また、ＧａＩｎＮＡｓを用いた面発光型半導体レーザ素子は、温度特性が良いこと、及び低しきい値であることにより、発熱が少なく、高温まで冷却なしで使えるシステムを実現できる。
【０１８０】
（第６の実施例）
図１２は本発明の第６の実施例の光送受信モジュールを示す図であり、この第６の実施例の光送受信モジュールは、第５の実施例の面発光型半導体レーザ素子と受信用フォトダイオードと光ファイバーとを組み合わせたものとなっている。
【０１８１】
本発明による面発光型半導体レーザ素子を光通信システムに用いる場合、面発光型半導体レーザ素子は低コストであるので、図１２に示すように送信用の面発光型半導体レーザ素子（１．３μｍ帯ＧａＩｎＮＡｓ面発光型半導体レーザ素子）と受信用フォトダイオードと光ファイバーとを組み合わせた光送信モジュールを用いた、低コスト，高信頼性の光通信システムを実現できる。また、本発明に係るＧａＩｎＮＡｓを用いた面発光型半導体レーザ素子の場合，温度特性が良いこと、動作電圧が低いこと、及び、低しきい値であることにより、発熱が少なく、高温まで冷却なしで使えるより低コストのシステムを実現できる。
【０１８２】
さらに、１．３μｍ等の長波長帯で低損失となるフッ素添加ＰＯＦ（プラスチックファイバ）とＧａＩｎＮＡｓを活性層に用いた面発光型レーザとを組み合わせると、ファイバが低コストであること、ファイバの径が大きくてファイバとのカップリングが容易で実装コストを低減できることから、極めて低コストのモジュールを実現できる。
【０１８３】
本発明に係る面発光型半導体レーザ素子を用いた光通信システムとしては、光ファイバーを用いた長距離通信に用いることができるのみならず、ＬＡＮ（Local Area Network）などのコンピュータ等の機器間伝送、さらにはボード間のデータ伝送、ボード内のＬＳＩ間，ＬＳＩ内の素子間等の光インターコネクションとして短距離通信に用いることができる。
【０１８４】
近年ＬＳＩ等の処理性能は向上しているが、これらを接続する部分の伝送速度が今後ボトルネックとなる。システム内の信号接続を従来の電気接続から光インターコネクトに変えると（例えばコンピュータシステムのボード間，ボード内のＬＳＩ間，ＬＳＩ内の素子間等を本発明に係る光送信モジュールや光送受信モジュールを用いて接続すると）、超高速コンピュータシステムが可能となる。
【０１８５】
また、複数のコンピュータシステム等を本発明に係る光送信モジュールや光送受信モジュールを用いて接続した場合、超高速ネットワークシステムが構築できる。特に面発光型半導体レーザ素子は端面発光型レーザに比べて桁違いに低消費電力化でき２次元アレイ化が容易なので、並列伝送型の光通信システムに適している。
【０１８６】
以上に説明したように、窒素を含む半導体層（活性層）であるＧａＩｎＮＡｓ系材料によると、ＧａＡｓ基板を用いた０．８５μｍ帯面発光型半導体レーザ素子などで実績のあるＡｌ（Ｇａ）Ａｓ／（Ａｌ）ＧａＡｓ系半導体多層膜分布ブラッグ反射鏡や、ＡｌＡｓの選択酸化による電流狭さく構造が適用でき、本発明による製造方法で面発光型半導体レーザ素子を製造することにより、ＧａＩｎＮＡｓ活性層の結晶品質の向上や、多層膜反射鏡の低抵抗化、面発光型半導体レーザ素子としての多層膜構造体の結晶品質や制御性の向上ができるので、実用レベルの高性能の１．３μｍ帯等の長波長帯面発光型半導体レーザ素子を実現でき、さらに、これらの素子を用いると、冷却素子が不要で低コストの光ファイバー通信システム，光インターコネクションシステムなどの光通信システムを実現することができる。
【０１８７】
（第７の実施例）
第７の実施例のＧａＩｎＮＡｓ面発光型半導体レーザ素子の構成は、第２の実施例で説明した図８と同じである。第７の実施例は、第２の実施例と次の点で違っている。すなわち、第７の実施例では、成長室内に残留したＡｌ原料，Ａｌ反応物，Ａｌ化合物，Ａｌのうちの少なくとも１つを除去する工程は、ＧａＡｓ下部スペーサ層の成長途中で成長中断し、一度被成長基板を別室に移動させ、被成長基板を保持していたサセプターを成長室に戻して、サセプターを成長温度より高い温度で加熱させて、キャリアガスであるＨ_２ガスとともにＣＢｒ_４を成長室に供給することによって行っている。
【０１８８】
第７の実施例では、装置内に残留したＡｌ系残留物が、窒素を含む活性層の成長時に酸素とともに活性層中に取りこまれないように、エッチングガスであるＣＢｒ_４を供給しているので、反応室内に残留したＡｌ系残留物は活性層の成長前に除外され、活性層中に酸素がＡｌとともに混入することを抑えることができる。これにより、第７の実施例では、発光効率が高く低しきい値で発振するＧａＩｎＮＡｓ面発光型半導体レーザ素子を量産に有利なＭＯＣＶＤ法で製造できた。なお、ＣＢｒ_４以外にもＣＨ_３Ｂｒ等のガスを用いることができる。
【０１８９】
また、本発明のように基板側がｐ型半導体となる構成であると、以下のような効果も得られる。すなわち、特開平１１−２７４０８３には、水素（Ｈ）のＧａＩｎＮＡｓ系活性層への混入が、発光特性を悪くするなどの問題の原因となることが示されている。一般的には、原子状水素によってアクセプターが不活性化される現象がＧａＡｓ，ＩｎＰ，ＡｌＧａＩｎＰなどで知られている。これはアニールによって活性化することができる。成長終了後の降温時にＡｓＨ_３の水素が原子状水素として最表面のｐ層（例えばｐ−ＧａＡｓ）から拡散するものである。原子状水素がｐ型半導体中の正孔の存在により電子を失い陽子となり拡散速度が加速するという説が検討されている。そして、これは表面をｎ層（例えばｎ−ＧａＡｓ）とすることで阻止できることが知られている。特に、ＭＯＣＶＤ法でＧａＩｎＮＡｓ系材料を形成する場合、Ｈ_２，ＡｓＨ_３などの水素化物が原料，雰囲気ガスとなっていること、ＤＭＨｙのようなＮの原料など原料に炭素（Ｃ）を含むこと、低温成長が好ましいことなどから、膜中にＣが取り込まれｐ型になり易く、水素が混入されやすい。本実施例のように基板側がｐ型半導体となる構成であると、ｎ型半導体を表面に構成でき、表面からの水素の混入を抑制できるといった効果も得られる。
【０１９０】
更には、ＧａＩｎＮＡｓ系活性層にｎ型となるドーパント（例えばＳｉ，Ｇｅ，Ｓｅ，Ｓ，Ｔｅ）を添加しｎ型半導体とすることで、ＧａＩｎＮＡｓ系活性層の成長中においても原子状水素が進入することを阻止できる。
【０１９１】
（第８の実施例）
第８の実施例のＧａＩｎＮＡｓ 面発光型半導体レーザ素子の構成は、第２の実施例及び第７の実施例で説明した図８と同じである。第８の実施例が第２の実施例と違うところは、ＧａＡｓ下部スペーサ層の成長途中で成長中断し、一度被成長基板を別室に移動させて成長室内に残留したＡｌ原料，Ａｌ反応物，Ａｌ化合物，Ａｌのうちの少なくとも１つを除去する工程を行なった後、被成長基板を成長室に戻して、サセプターの温度を所定のエッチング温度に加熱し、キャリアガスであるＨ_２ガスとともにＣＢｒ_４を成長室に供給して、被成長基板の表面をエッチング除去し、その後に残りの結晶成長（再成長）を行ったことである。
【０１９２】
Ａｌ系残留物の除去を成長中断して行なう場合には、被成長基板の表面が酸化やその他のダメージを受けて欠陥が発生する恐れがある。本実施例では、再成長界面と窒素を含む活性層との間に再成長界面を形成する半導体層（本実施例ではＧａＡｓスペーサ層）よりもバンドギャップの大きいＧａＰＡｓ層を設けた他に、再成長前に被成長基板の表面をエッチング除去しているので（ＧａＡｓなどの化合物半導体をエッチングする効果のある臭素を含むガスを供給して、被成長基板の表面であるＧａＡｓスペーサ層の一部をエッチング除去しているので）、再成長界面での非発光再結合などの素子特性への悪影響をより確実に抑えることができた。なお、面発光レーザでは厚さの制御が重要なので、エッチング深さを予想してあらかじめエッチングする分を厚く成長しておいた。これの他にも再成長時にエッチングする分を厚く成長することでも対応できる。また、臭素を含むガスとして、ＣＢｒ_４以外にも、ＣＨ_３Ｂｒ等のガスを用いることができる。
【０１９３】
これにより、第８の実施例では、発光効率が高く低しきい値で発振するＧａＩｎＮＡｓ面発光型半導体レーザ素子を量産に有利なＭＯＣＶＤ 法で製造できた。
【０１９４】
【発明の効果】
以上に説明したように、請求項１乃至請求項７記載の発明によれば、窒素を含む活性層と半導体基板との間にｐ型半導体層を有し、ｐ型半導体層中にＡｌとＡｓを含む被選択酸化層を配置し、配置された被選択酸化層の一部を選択的に酸化して電流狭窄構造を形成する半導体発光素子の製造方法であって、被選択酸化層の成長後、窒素を含む活性層の成長開始までの間に、窒素化合物原料または窒素化合物原料中に含まれる不純物が触れる場所となるガス供給ライン中もしくは成長室内に残留したＡｌ原料，Ａｌ反応物，Ａｌ化合物，Ａｌのうちの少なくとも１つを除去する工程を設けるので、活性層への酸素の取り込みを抑えることができ、発光効率が高い半導体発光素子を作製することができる。
【０１９５】
特に、請求項２記載の発明では、請求項１記載の半導体発光素子の製造方法において、被選択酸化層の成長後、窒素を含む活性層の成長開始までの間に、窒素化合物原料または窒素化合物原料中に含まれる不純物が触れる場所となるガス供給ライン中もしくは成長室内に残留したＡｌ原料，Ａｌ反応物，Ａｌ化合物，Ａｌのうちの少なくとも１つを除去する工程は、成長を中断し、キャリアガスでガス供給ラインもしくは成長室をパージする工程であるので、反応室側壁，加熱帯，基板を保持する治具等に残留しているＡｌ系残留物を除去し、活性層への酸素の取り込みを抑えることができ、発光効率が高い半導体発光素子を作製できる。
【０１９６】
また、請求項３記載の発明では、請求項２記載の半導体発光素子の製造方法において、前記成長中断中に、サセプターをベーキングするので、効率的に活性層への酸素の取り込みを抑えることができ、発光効率が高い半導体発光素子を作製できる。
【０１９７】
また、請求項４記載の発明によれば、請求項１記載の半導体発光素子の製造方法において、被選択酸化層の成長後、窒素を含む活性層の成長開始までの間に、窒素化合物原料または窒素化合物原料中に含まれる不純物が触れる場所となるガス供給ライン中もしくは成長室内に残留したＡｌ原料，Ａｌ反応物，Ａｌ化合物，Ａｌのうちの少なくとも１つを除去する工程は、エッチングガスを成長室に供給する工程であるので、活性層への酸素の取り込みを抑えることができ、発光効率の高い半導体発光素子を得ることができる。
【０１９８】
また、請求項５記載の発明によれば、請求項４記載の半導体発光素子の製造方法において、前記エッチングガスは、有機系窒素化合物ガスであり、有機系窒素化合物ガスは、反応室側壁，加熱帯，基板を保持する治具等に残留しているＡｌ系残留物と反応しＡｌ系残留物を除去することができるので、活性層への酸素の取り込みを抑えることができ、発光効率の高い半導体発光素子を得ることができる。
【０１９９】
また、請求項６記載の発明によれば、請求項４記載の半導体発光素子の製造方法において、前記エッチングガスは、酸素（Ｏ）を含むガスであり、酸素（Ｏ）を含むガスは、反応室側壁，加熱帯，基板を保持する治具等に残留しているＡｌ系残留物と反応しＡｌ系残留物を除去することのできるので、活性層への酸素の取り込みを抑えることができ、発光効率の高い半導体発光素子を得ることができる。
【０２００】
また、請求項７記載の発明によれば、請求項４記載の半導体発光素子の製造方法において、前記エッチングガスは、塩素（Ｃｌ）を含むガスであり、塩素（Ｃｌ）を含むガスは、反応室側壁，加熱帯，基板を保持する治具等に残留しているＡｌ系残留物と反応しＡｌ系残留物を除去することができるので、活性層への酸素の取り込みを抑えることができ、発光効率の高い半導体発光素子を得ることができる。
【０２０１】
また、請求項８乃至請求項１４記載の発明によれば、窒素を含む活性層と半導体基板との間にｐ型半導体層を有し、ｐ型半導体層中にＡｌとＡｓを含む被選択酸化層を配置し、配置された被選択酸化層の一部を選択的に酸化して電流狭窄構造を形成し、また、被選択酸化層と窒素を含む活性層との間に、少なくとも一層のＧａＩｎＰＡｓ層、または、ＧａＩｎＰ層、または、ＧａＰＡｓ層を形成する半導体発光素子の製造方法であって、被選択酸化層の成長後、前記ＧａＩｎＰＡｓ層、または、ＧａＩｎＰ層、または、ＧａＰＡｓ層の成長が完了するまでの間に、窒素化合物原料または窒素化合物原料中に含まれる不純物が触れる場所となるガス供給ライン中もしくは成長室内に残留したＡｌ原料，Ａｌ反応物，Ａｌ化合物，Ａｌのうちの少なくとも１つを除去する工程を設けるようになっており、キャリアの注入されない活性領域外で、成長中断してＡｌ系残留物を除去することで、残留Ａｌに起因する非発光再結合やＡｌ系残留物除去工程に起因する非発光再結合によって発光効率が低下することを抑制できる。
【０２０２】
特に、請求項９記載の発明では、請求項８記載の半導体発光素子の製造方法において、請求項８記載の半導体発光素子の製造方法において、被選択酸化層の成長後、前記ＧａＩｎＰＡｓ層、または、ＧａＩｎＰ層、または、ＧａＰＡｓ層の成長が完了するまでの間に、窒素化合物原料または窒素化合物原料中に含まれる不純物が触れる場所となるガス供給ライン中もしくは成長室内に残留したＡｌ原料，Ａｌ反応物，Ａｌ化合物，Ａｌのうちの少なくとも１つを除去する工程は、成長を中断し、キャリアガスでガス供給ラインもしくは成長室をパージする工程であるので、反応室側壁，加熱帯，基板を保持する治具等に残留しているＡｌ系残留物を除去し、活性層への酸素の取り込みを抑えることができ、発光効率が高い半導体発光素子を作製できる。
【０２０３】
また、請求項１０記載の発明では、請求項８記載の半導体発光素子の製造方法において、前記成長中断中に、サセプターをベーキングするので、効率的に活性層への酸素の取り込みを抑えることができ、発光効率が高い半導体発光素子を作製できる。
【０２０４】
また、請求項１１記載の発明によれば、請求項８記載の半導体発光素子の製造方法において、被選択酸化層の成長後、窒素を含む活性層の成長開始までの間に、窒素化合物原料または窒素化合物原料中に含まれる不純物が触れる場所となるガス供給ライン中もしくは成長室内に残留したＡｌ原料，Ａｌ反応物，Ａｌ化合物，Ａｌのうちの少なくとも１つを除去する工程は、エッチングガスを成長室に供給する工程であるので、活性層への酸素の取り込みを抑えることができ、発光効率の高い半導体発光素子を得ることができる。
【０２０５】
また、請求項１２記載の発明によれば、請求項８記載の半導体発光素子の製造方法において、前記エッチングガスは、有機系窒素化合物ガスであり、有機系窒素化合物ガスは、反応室側壁，加熱帯，基板を保持する治具等に残留しているＡｌ系残留物と反応しＡｌ系残留物を除去することができるので、活性層への酸素の取り込みを抑えることができ、発光効率の高い半導体発光素子を得ることができる。
【０２０６】
また、請求項１３記載の発明によれば、請求項８記載の半導体発光素子の製造方法において、前記エッチングガスは、酸素（Ｏ）を含むガスであり、酸素（Ｏ）を含むガスは、反応室側壁，加熱帯，基板を保持する治具等に残留しているＡｌ系残留物と反応しＡｌ系残留物を除去することのできるので、活性層への酸素の取り込みを抑えることができ、発光効率の高い半導体発光素子を得ることができる。
【０２０７】
また、請求項１４記載の発明によれば、請求項８記載の半導体発光素子の製造方法において、前記エッチングガスは、塩素（Ｃｌ）を含むガスであり、塩素（Ｃｌ）を含むガスは、反応室側壁，加熱帯，基板を保持する治具等に残留しているＡｌ系残留物と反応しＡｌ系残留物を除去することができるので、活性層への酸素の取り込みを抑えることができ、発光効率の高い半導体発光素子を得ることができる。
【０２１１】
また、請求項１５乃至請求項１７記載の発明によれば、窒素を含む活性層と半導体基板との間にｐ型半導体層を有し、ｐ型半導体層中に配置されたＡｌとＡｓを含む被選択酸化層の一部が選択的に酸化されて電流狭窄構造が形成されている半導体発光素子において、前記被選択酸化層と窒素を含む活性層との間に、活性層よりもバンドギャップが大きくかつ窒素を含む半導体層が形成されているので、成長時、成長室内に残留したＡｌ原料，Ａｌ反応物，Ａｌ化合物，Ａｌのうちの少なくとも１つを除去し、活性層への酸素の取り込みを抑えることができ、発光効率を高くできる。また、半導体レーザの場合、しきい値電流を充分低いものとすることができる。
【０２１２】
特に、請求項１６記載の発明によれば、請求項１５記載の半導体発光素子において、活性層よりもバンドギャップが大きくかつ窒素を含む半導体層は、ＧａＮＡｓ，ＧａＩｎＮＡｓ，ＧａＩｎＮＰ，ＧａＮＰＡｓ，ＧａＩｎＮＰＡｓのいずれかであるので、発光効率を高くできる。また、半導体レーザの場合、しきい値電流を充分低いものとすることができる。
【０２１３】
また、請求項１７記載の発明によれば、請求項１５記載の半導体発光素子において、活性層よりもバンドギャップが大きくかつ窒素を含む半導体層と窒素を含む活性層との間に、その両者よりもバンドギャップエネルギーが大きいＧａＡｓ，ＧａＩｎＡｓ，ＧａＡｓＰ，ＧａＩｎＰＡｓ，ＧａＩｎＰのいずれか１つからなる層が形成されているので、活性層よりもバンドギャップが大きくかつ窒素を含む半導体層への注入キャリアがほとんど無くなり、発光効率を高くできる。また、半導体レーザの場合、しきい値電流を充分低いものとすることができる。
【０２１４】
また、請求項１８乃至請求項２０記載の発明によれば、窒素を含む活性層を有する活性領域と、レーザ光を得るために活性層の上部および下部に設けられた上部反射鏡および下部反射鏡とを含む共振器構造を備え、窒素を含む活性層と半導体基板との間にｐ型半導体層を有している面発光型半導体レーザ素子の製造方法であって、前記下部反射鏡は、屈折率が周期的に変化し入射光を光波干渉によって反射する半導体分布ブラッグ反射鏡を含み、該半導体分布ブラッグ反射鏡の屈折率が小さい層はＡｌ_ｘＧａ_{1- ｘ}Ａｓ（０＜ｘ≦１）からなり、また、該半導体分布ブラッグ反射鏡の屈折率が大きい層はＡｌ_ｙＧａ_{1- ｙ}Ａｓ（０≦ｙ＜ｘ≦１）からなり、前記ｐ型半導体層の一部を選択的に酸化して電流狭窄を行うためのＡｌとＡｓを含む被選択酸化層を有し、被選択酸化層と窒素を含む活性層との間に、少なくとも１層のＧａＩｎＰＡｓ層、または、ＧａＩｎＰ層、または、ＧａＰＡｓ層を形成し、前記被選択酸化層の成長後、前記ＧａＩｎＰＡｓ層、または、ＧａＩｎＰ層、または、ＧａＰＡｓ層の成長が完了するまでの間に、窒素化合物原料または窒素化合物原料中に含まれる不純物が触れる場所となるガス供給ライン中もしくは成長室内に残留したＡｌ原料，Ａｌ反応物，Ａｌ化合物，Ａｌのうちの少なくとも１つを除去する工程を設けるので、窒素を含む活性層への酸素の取りこまれが抑制され、かつ成長中断して形成された欠陥による非発光再結合の影響が避けられ、低抵抗で駆動電圧が低く、しかも発光効率が高く、低しきい値電流動作し、温度特性が良い面発光型半導体レーザ素子を容易に低コストで作製できる。
【０２１５】
特に、請求項１９記載の発明によれば、請求項１８記載の面発光型半導体レーザ素子の製造方法において、被選択酸化層の成長後、窒素を含む活性層の成長開始までの間に、窒素化合物原料または窒素化合物原料中に含まれる不純物が触れる場所となるガス供給ライン中もしくは成長室内に残留したＡｌ原料，Ａｌ反応物，Ａｌ化合物，Ａｌのうちの少なくとも１つを除去する工程は、成長を中断し、キャリアガスでガス供給ラインもしくは成長室をパージする工程であるので、窒素を含む活性層への酸素の取りこまれを効率的に抑制でき、低抵抗で駆動電圧が低く、しかも発光効率が高く、低しきい値電流動作し、温度特性が良い面発光型半導体レーザ素子を容易に低コストで実現できる。
【０２１６】
また、請求項２０記載の発明では、成長中断中にサセプターをベーキングするので、窒素を含む活性層への酸素の取りこまれを効率的に抑制でき、低抵抗で駆動電圧が低く、しかも発光効率が高く、低しきい値電流動作し、温度特性が良い面発光型半導体レーザ素子を容易に低コストで実現できる。
【０２１８】
また、請求項２１乃至請求項２３記載の発明によれば、窒素を含む活性層を有する活性領域と、レーザ光を得るために活性層の上部および下部に設けられた上部反射鏡および下部反射鏡とを含む共振器構造を備え、窒素を含む活性層と半導体基板との間にｐ型半導体層を有している面発光型半導体レーザ素子であって、前記下部反射鏡は、屈折率が周期的に変化し入射光を光波干渉によって反射する半導体分布ブラッグ反射鏡を含み、該半導体分布ブラッグ反射鏡の屈折率が小さい層はＡｌ_ｘＧａ_{1- ｘ}Ａｓ（０＜ｘ≦１）からなり、また、該半導体分布ブラッグ反射鏡の屈折率が大きい層はＡｌ_ｙＧａ_{1- ｙ}Ａｓ（０≦ｙ＜ｘ≦１）からなり、前記ｐ型半導体層の一部を選択的に酸化して電流狭窄を行うためのＡｌとＡｓを含む被選択酸化層を有し、被選択酸化層と窒素を含む活性層との間に、活性層よりもバンドギャップが大きくかつ窒素を含む半導体層が形成されているので、窒素を含む活性層への酸素の取りこまれが抑制され、低抵抗で駆動電圧が低く、しかも発光効率が高く、低しきい値電流動作し、温度特性が良い面発光型半導体レーザ素子を容易に低コストで実現できる。更に、本構成によれば、ｐ型基板を用いることができる。
【０２１９】
特に、請求項２２記載の発明によれば、請求項２１記載の面発光型半導体レーザ素子において、活性層よりもバンドギャップが大きくかつ窒素を含む半導体層は、ＧａＮＡｓ，ＧａＩｎＮＡｓ，ＧａＩｎＮＰ，ＧａＮＰＡｓ，ＧａＩｎＮＰＡｓのいずれかであるので、窒素を含む活性層への酸素の取りこまれが抑制され、低抵抗で駆動電圧が低く、しかも発光効率が高く低しきい値電流動作し、温度特性が良い面発光型半導体レーザ素子を容易に低コストで実現できる。
【０２２０】
また、請求項２３記載の発明によれば、請求項２１記載の面発光型半導体レーザ素子において、活性層よりもバンドギャップが大きくかつ窒素を含む半導体層と窒素を含む活性層との間に、その両者よりもバンドギャップエネルギーが大きいＧａＡｓ，ＧａＩｎＡｓ，ＧａＡｓＰ，ＧａＩｎＰＡｓ，ＧａＩｎＰのいずれか１つからなる層が形成されているので、活性層よりバンドギャップが大きくかつ窒素を含む半導体層への注入キャリアがほとんど無くなり、低抵抗で駆動電圧が低く、しかも発光効率が高く、低しきい値電流動作し、温度特性が良い面発光型半導体レーザ素子を容易に低コストで実現できる。
【０２２１】
また、請求項２４記載の発明によれば、請求項２１乃至請求項２３のいずれか一項に記載の面発光型半導体レーザ素子が複数個配列されて構成されている面発光型半導体レーザアレイであるので、複数の素子により同時により多くのデータを伝送することができる。
【０２２２】
また、請求項２５記載の発明によれば、請求項２１乃至請求項２３のいずれか一項に記載の面発光型半導体レーザ素子、または、請求項２４記載の面発光型半導体レーザアレイが光源として用いられている光送信モジュールであり、上述したような低抵抗で駆動電圧が低く、低しきい値電流動作し、温度特性が良い本発明の面発光型半導体レーザ素子や面発光型半導体レーザアレイが用いられることによって、冷却素子が不要な低コストな光送信モジュールを実現することができる。
【０２２３】
また、請求項２６記載の発明によれば、請求項２１乃至請求項２３のいずれか一項に記載の面発光型半導体レーザ素子、または、請求項２４記載の面発光型半導体レーザアレイが光源として用いられている光送受信モジュールであり、上述したような低抵抗で駆動電圧が低く、低しきい値電流動作し、温度特性が良い本発明の面発光型半導体レーザ素子や面発光型半導体レーザアレイが用いられることによって、冷却素子が不要な低コストな光送受信モジュールを実現することができる。
【０２２４】
また、請求項２７記載の発明によれば、請求項２１乃至請求項２３のいずれか一項に記載の面発光型半導体レーザ素子、または、請求項２４記載の面発光型半導体レーザアレイが光源として用いられている光通信システムであり、上述したような低抵抗で駆動電圧が低く、低しきい値電流動作し、温度特性が良い本発明の面発光型半導体レーザ素子や面発光型半導体レーザアレイが用いられることによって、冷却素子不要な低コストな光ファイバー通信システム，光インターコネクションシステムなどの光通信システムを実現することができる。
【０２２５】
また、請求項２８記載の発明によれば、基板と活性層との間にＡｌを含む半導体層が設けられる半導体発光素子の製造方法であって、前記Ａｌを含む半導体層を成長した後であって、窒素を含む活性層の成長を開始する前に、エッチングガスとして臭素を含んだガスを成長室内に供給し、成長室内に残留したＡｌ原料，Ａｌ反応物，Ａｌ化合物，Ａｌのうちの少なくとも１つを除去する工程を設けたので、発光効率の高い半導体発光素子を得ることができる。すなわち、ＣＢｒ_４のような臭素を含んだガスは、成長室内の反応生成堆積物と反応し、エッチング除去する効果がある。よって、Ａｌを含んだ半導体層を成長した後、窒素を含む活性層の成長の前までに、エッチングガスとして臭素を含んだガスを供給すると、装置内のＡｌ系残留物と反応してＡｌ系残留物を除去することができるので、活性層への酸素の取り込みを抑えることができ、発光効率の高い半導体発光素子を得ることができる。
【０２２６】
また、請求項２９記載の発明によれば、基板と活性層との間にＡｌを含む半導体層が設けられる半導体発光素子の製造方法であって、前記Ａｌを含む半導体層を成長した後であって、窒素を含む活性層の成長を開始する前に成長を一度中断し、再成長する前にエッチングガスとして臭素を含んだガスを成長室内に供給し、被成長基板の表面の一部を除去する工程を設けたので、発光効率の高い半導体発光素子を得ることができる。すなわち、臭素を含んだガスは、ＧａＡｓなどの半導体層をエッチングする効果がある。成長中断をして、成長室内に残留したＡｌ系残留物を除去する場合、エピ基板表面には酸化膜等が形成される恐れがある。再成長する前にエッチングガスとして臭素を含んだガスを成長室内に供給し、被成長基板の表面の一部を除去する工程を設けると、酸化膜等を除去できるので、再成長界面での非発光再結合などの素子特性への悪影響を抑えられ、発光効率の高い半導体発光素子を得ることができる。
【図面の簡単な説明】
【図１】本願の発明者が実験的に求めたしきい値電流密度の窒素組成依存性を示す図である。
【図２】一般的なＭＯＣＶＤ装置の概略を示す図である。
【図３】ＭＯＣＶＤ装置で作製したＧａＩｎＮＡｓ量子井戸層（窒素を含んだ半導体層）とＧａＡｓバリア層とからなるＧａＩｎＮＡｓ／ＧａＡｓ２重量子井戸構造（活性層）の室温フォトルミネッセンススペクトルを示す図である。
【図４】図３の測定に用いた試料構造を示す図である。
【図５】図４に示した半導体発光素子の一例として、クラッド層をＡｌＧａＡｓとし、中間層をＧａＡｓとし、活性層をＧａＩｎＮＡｓ／ＧａＡｓ２重量子井戸構造として構成した素子を１台のエピタキシャル成長装置（ＭＯＣＶＤ）を用いて形成したときの、窒素（Ｎ）濃度と酸素（Ｏ）濃度の深さ方向分布を示す図である。
【図６】図５と同じ試料のＡｌ濃度の深さ方向分布を示す図である。
【図７】本発明の第１の実施例のＧａＩｎＮＡｓ面発光型半導体レーザ素子を示す図である。
【図８】本発明の第２，第７，第８の実施例のＧａＩｎＮＡｓ面発光型半導体レーザ素子を示す図である。
【図９】本発明の第３の実施例のＧａＩｎＮＡｓ面発光型半導体レーザ素子を示す図である。
【図１０】本発明の第４の実施例のＧａＩｎＮＡｓ面発光型半導体レーザアレイ（ＧａＩｎＮＡｓ面発光型半導体レーザアレイチップ）を示す図である。
【図１１】本発明の第５の実施例の光送信モジュールを示す図である。
【図１２】本発明の第６の実施例の光送受信モジュールを示す図である。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a semiconductor light emitting device manufacturing method, a semiconductor light emitting device, a surface emitting semiconductor laser device manufacturing method, a surface emitting semiconductor laser device, a surface emitting semiconductor laser array, an optical transmission module, an optical transmission / reception module, and an optical communication system. About.
[0002]
[Prior art]
In recent years, as seen in the explosive spread of the Internet, the amount of information handled has increased dramatically and is expected to accelerate further in the future. For this reason, not only trunk lines but also subscriber lines such as homes and offices and transmission lines close to users such as LAN (Local Area Network), and further, optical fibers are introduced into the wiring between each equipment and within the equipment, Large-capacity information transmission technology using light is extremely important.
[0003]
Furthermore, parallel transmission using a semiconductor laser array in which a plurality of semiconductor lasers are integrated has been attempted in order to transmit more data at the same time. In this case, a bipolar transistor drive circuit capable of high-speed operation is often used, and a semiconductor laser using a p-type substrate is used because it becomes an anode common.
[0004]
In addition, in order to increase the capacity of optical networks and optical wiring at low cost without worrying about the distance, the 1.3 μm band and 1.55 μm band, which have a low transmission loss of silica fiber and good consistency as a light source, are used. The vertical cavity surface emitting laser (VCSEL) is very promising. The surface emitting semiconductor laser device is suitable for low cost, low power consumption, small size, and two-dimensional integration as compared with the edge emitting laser, and is already in a high-speed LAN in the 0.85 μm band that can be actually formed on a GaAs substrate. It has been put to practical use with 1Gbit / s Ethernet.
[0005]
In the surface emitting semiconductor laser element, current confinement is performed by an Al oxide film that selectively oxidizes a part of a selective oxidation layer mainly composed of Al and As in order to perform current injection efficiently. The current confinement layer is provided at a position close to the active layer in the p-side region for the purpose. Specifically, the current confinement layer is formed on the low refractive index layer closest to the active layer of the multilayer reflector using an AlGaAs material and periodically laminating a low refractive index layer and a high refractive index layer. There are many cases. By forming the current confinement layer close to the active layer, the spread of current can be suppressed, and carriers can be confined efficiently in a minute region that is not exposed to the atmosphere. Further, by oxidizing to an Al oxide film, the refractive index is reduced, and light can be efficiently confined in a minute region where carriers are confined by the effect of the convex lens, so that the efficiency is improved and the threshold current is reduced. Can be reduced. Further, since the current confinement structure can be easily formed, the manufacturing cost can be reduced, and it is often used recently.
[0006]
In the 1.3 μm band, the material system on the InP substrate is common, and the edge emitting laser has a track record. However, this conventional long-wavelength semiconductor laser has a major drawback that the operating current increases three times when the environmental temperature is changed from room temperature to 80 ° C. In addition, since there is no material suitable for a reflecting mirror in a surface-emitting type semiconductor laser element, it is difficult to achieve high performance, and a practical level of characteristics has not been obtained.
[0007]
For this reason, the current highest performance is obtained by the structure in which the active layer on the InP substrate and the AlGaAs / GaAs reflector on the GaAs substrate are bonded together directly (references “V. Jayaraman, JC Geske, MH MacDougal FH Peters, TD Lowes, and TT Char, Electron. Lett., 34, (14), pp. 1405-1406, 1998.).
[0008]
However, this method is inevitably associated with an increase in cost and is problematic in terms of mass productivity. Therefore, recently, a material system capable of forming a 1.3 μm band on a GaAs substrate has attracted attention, and (Ga) InAs quantum dots, GaAsSb, and GaInNAs (for example, see JP-A-6-37355) have been studied. Among these, GaInNAs has attracted attention as a novel material that can extremely reduce the temperature dependence of laser characteristics.
[0009]
Since the band gap of the GaInNAs semiconductor laser on the GaAs substrate is reduced by adding nitrogen, a long wavelength band such as a 1.3 μm band can be formed on the GaAs substrate. When the In composition is 10%, the nitrogen (N) composition is about 3% and a 1.3 μm band can be formed. However, the larger the nitrogen (N) composition is, the higher the threshold current density is.
[0010]
FIG. 1 is a graph showing the nitrogen composition dependence of the threshold current density experimentally determined by the inventor of the present application. The horizontal axis represents the nitrogen (N) composition ratio (%), and the vertical axis represents the threshold value. The current density is shown. As described above, the reason why the threshold current density rapidly increases as the nitrogen composition increases is that the crystallinity of the GaInNAs layer deteriorates as the nitrogen composition increases.
[0011]
Therefore, how to grow GaInNAs with high quality becomes a problem. As such GaInNAs crystal growth methods, MOCVD (Metal Organic Chemical Vapor Deposition) and MBE (Molecular Beam Epitaxy) have been tried.
[0012]
Of these, the MOCVD method does not require a high vacuum like the MBE method, and in the MBE method, the material supply is controlled by changing the temperature of the cell, whereas the material gas flow rate only needs to be controlled. In addition, since the growth rate can be increased and the throughput can be easily increased, the growth method is extremely suitable for mass production. The MOCVD method is used in all (in most cases) production of 0.85 μm band surface emitting semiconductor laser devices that are actually put into practical use.
[0013]
[Problems to be solved by the invention]
However, according to conventional reports on GaInNAs-based surface-emitting semiconductor laser elements, there are few examples of GaInNAs-based surface-emitting semiconductor laser elements grown by MOCVD suitable for mass production, and many of them are grown by MBE. It does not have sufficient characteristics. That is, since the resistance of the p-side multilayer reflector is extremely high in the growth by the MBE method, a method that does not use the p-side multilayer reflector as a current path is used. It had problems such as becoming.
[0014]
Thus, conventionally, a method for manufacturing a GaInNAs-based surface-emitting semiconductor laser device by MOCVD suitable for mass production has not yet been established, but is gradually being established by the inventors of the present application.
[0015]
First, the experimental results of the inventors of the present application will be described as the cause of hindering the high performance of the GaInNAs surface emitting semiconductor laser element by the MOCVD method.
[0016]
FIG. 2 is a diagram showing an outline of a general MOCVD apparatus. The MOCVD method is a vapor phase growth method in which at least a part of an organic metal raw material is used and crystal growth is performed by thermal decomposition of a raw material gas and a surface reaction with a substrate to be grown. As shown in FIG. 2, the MOCVD apparatus has reacted with a source gas supply unit to which source gas is supplied, a heating means (not shown) for heating the substrate to be grown, and a heating unit (heating body). And an exhaust part (exhaust pump or the like) for exhausting the gas. Here, in order to prevent air from entering the growth chamber (reaction chamber), the substrate is usually introduced from the substrate inlet / outlet and transferred to the growth chamber (reaction chamber) after evacuation by the exhaust section. Further, the source gas supply unit is usually divided into a group III gas line and a group V gas line. And in the example of FIG. 2, it is comprised so that a III group raw material and a V group raw material may merge before the reaction chamber entrance.
[0017]
Further, a reduced pressure of about 50 Torr to 100 Torr is often used as the pressure in the growth chamber (reaction chamber). For the raw material, an organic metal such as Ga: TMG (trimethylgallium), TEG (triethylgallium), Al: TMA (trimethylaluminum), In: TMI (trimethylindium) is used as a group III raw material. In addition, group V raw materials include AsH₃(Arsine), TBA (tertiary butyl arsine), PH₃Hydride gas and organic compounds such as (phosphine) and TBP (tertiarybutylarsine) are generally used.
[0018]
The carrier gas includes hydrogen gas (H₂) Is usually used, and the carrier gas is usually supplied after removing impurities through a hydrogen purifier. An organic compound such as DMHy (dimethylhydrazine) or MMHy (monomethylhydrazine) can be used as a nitrogen source for growing a semiconductor layer containing nitrogen. In addition, a raw material is not restricted to this. Liquid or solid raw materials such as organic metals and organic nitrogen compounds are supplied by being bubbled through a carrier gas in a bubbler. The hydride is supplied in a gas cylinder. In FIG. 2, TMG, TMA, TMI and DMHy use bubblers (liquid, solid material bubblers) and AsH₃And a dopant gas (only one type is shown in FIG. 2) uses a gas cylinder.
[0019]
Necessary materials and compositions can be grown by switching the path of the source gas with a valve and controlling the supply amount with an MFC mass flow controller or the like. Generally, each group III gas line and group V gas line has a main line for supplying gas to the reaction chamber, a vent line for supplying gas to the exhaust pump, and a dummy line (in the figure) in addition to the raw material line. , Dummy lines 1 and 2) are provided, and the valves are switched so as to merge with either the main line or the vent line, and the gas flow is reduced by eliminating the pressure difference between the main line and the vent line. I try not to disturb as much as possible. Note that the carrier gas is also supplied to the main line, the vent line, and the dummy line.
[0020]
When growing a semiconductor light emitting device or the like having a plurality of semiconductor layers, crystal growth is performed by supplying necessary raw materials for each layer to the main line side and supplying a dummy line for supplying a carrier gas to the vent side. The growth thickness is controlled by the supply time of the source gas. As a result, a necessary structure can be grown. Therefore, the MOCVD method has a high throughput and is suitable for mass production.
[0021]
FIG. 3 shows a room temperature photoluminescence spectrum of a GaInNAs / GaAs double quantum well structure (active layer) composed of a GaInNAs quantum well layer (nitrogen-containing semiconductor layer) and a GaAs barrier layer produced by such an MOCVD apparatus. Has been. FIG. 4 is a diagram showing a sample structure used in the measurement of FIG. In this sample structure, a lower cladding layer 202, an intermediate layer 203, an active layer 204 containing nitrogen, an intermediate layer 203, and an upper cladding layer 205 are sequentially stacked on a GaAs substrate 201.
[0022]
In FIG. 3, symbol A indicates a sample in which a double quantum well structure is formed on an AlGaAs cladding layer with a GaAs intermediate layer interposed therebetween, and symbol B indicates 2 on a GaInP cladding layer with a GaAs intermediate layer interposed therebetween. The sample which formed the quantum well structure continuously is shown.
[0023]
As shown in FIG. 3, the photoluminescence intensity in sample A is lower than half that in sample B. Therefore, when an active layer containing nitrogen such as GaInNAs is continuously formed on a semiconductor layer containing Al as a constituent element using a single MOCVD apparatus, the emission intensity of the active layer is deteriorated. It turns out that the problem of becoming will arise. For this reason, the threshold current density of the GaInNAs laser formed on the AlGaAs cladding layer is several times higher than that formed on the GaInP cladding layer.
[0024]
In particular, for example, in order to fabricate a surface emitting laser array, a p-type semiconductor layer is formed on a semiconductor substrate, and then an active layer containing nitrogen is formed. The p-type semiconductor layer is mainly selected from AlAs. In the case where an oxide layer is arranged and a part of the arranged selective oxidation layer is selectively oxidized to form a current confinement structure, an active layer containing nitrogen and a selective oxidation layer made of an AlAs-based material are provided. The structure is close, and the above result is extremely problematic (that is, the emission intensity of the active layer is deteriorated).
[0025]
The present invention has a structure in which an active layer containing nitrogen is formed after forming a p-type semiconductor layer, a selective oxidation layer mainly composed of AlAs is arranged in the p-type semiconductor layer, and the selective oxidation layer arranged Semiconductor light-emitting device manufacturing method and semiconductor capable of preventing the problem that the emission intensity of the active layer is deteriorated even when a current confinement structure is formed by selectively oxidizing a part of the semiconductor It is an object of the present invention to provide a method for manufacturing a light emitting element and a surface emitting semiconductor laser element, a surface emitting semiconductor laser element, a surface emitting semiconductor laser array, an optical transmission module, an optical transmission / reception module, and an optical communication system.
[0026]
[Means for Solving the Problems]
  In order to achieve the above object, the invention described in claim 1 has a p-type semiconductor layer between the active layer containing nitrogen and the semiconductor substrate, and the p-type semiconductor layer includes the p-type semiconductor layer.Contains Al and AsA method for manufacturing a semiconductor light emitting device, comprising a selective oxidation layer and selectively oxidizing a portion of the arranged selective oxidation layer to form a current confinement structure, wherein after the growth of the selective oxidation layer, nitrogen is formed Al source material, Al reactant, Al compound, Al remaining in the gas supply line or in the growth chamber where the nitrogen compound raw material or impurities contained in the nitrogen compound raw material come into contact before the start of growth of the active layer containing A step of removing at least one of the above is provided.
[0027]
According to a second aspect of the present invention, in the method for manufacturing a semiconductor light emitting device according to the first aspect, the nitrogen compound raw material or the nitrogen compound is formed after the growth of the selective oxidation layer and before the start of the growth of the active layer containing nitrogen. The step of removing at least one of the Al raw material, Al reactant, Al compound, and Al remaining in the gas supply line or the growth chamber where the impurities contained in the raw material come into contact is interrupted by the growth, and the carrier It is a process of purging a gas supply line or a growth chamber with gas.
[0028]
According to a third aspect of the present invention, in the method of manufacturing a semiconductor light emitting device according to the second aspect, the susceptor is baked during the growth interruption.
[0029]
According to a fourth aspect of the present invention, in the method for manufacturing a semiconductor light emitting device according to the first aspect, the nitrogen compound raw material or the nitrogen compound is formed between the growth of the selective oxidation layer and the start of the growth of the active layer containing nitrogen. The step of removing at least one of the Al raw material, Al reactant, Al compound, and Al remaining in the gas supply line or the growth chamber where the impurities contained in the raw material come into contact with each other is performed by using an etching gas in the growth chamber. It is the process of supplying.
[0030]
According to a fifth aspect of the present invention, in the method for manufacturing a semiconductor light emitting device according to the fourth aspect, the etching gas is an organic nitrogen compound gas.
[0031]
According to a sixth aspect of the present invention, in the method for manufacturing a semiconductor light emitting device according to the fourth aspect, the etching gas is a gas containing oxygen (O).
[0032]
According to a seventh aspect of the present invention, in the method for manufacturing a semiconductor light emitting device according to the fourth aspect, the etching gas is a gas containing chlorine (Cl).
[0033]
  The invention according to claim 8 has a p-type semiconductor layer between the active layer containing nitrogen and the semiconductor substrate, and the p-type semiconductor layer includes the p-type semiconductor layer.Contains Al and AsA selective oxidation layer is disposed, a part of the disposed selective oxidation layer is selectively oxidized to form a current confinement structure, and at least between the selective oxidation layer and the active layer containing nitrogen. A method for manufacturing a semiconductor light emitting device for forming a single GaInPAs layer, a GaInP layer, or a GaPAs layer, wherein the growth of the selective oxidation layer is followed by the growth of the GaInPAs layer, the GaInP layer, or the GaPAs layer. In the gas supply line where the nitrogen compound raw material or impurities contained in the nitrogen compound raw material come into contact or in the growth chamber, at least of the Al raw material, Al reactant, Al compound, and Al remaining in the growth chamber It is characterized by providing a step of removing one.
[0034]
According to a ninth aspect of the present invention, in the method for manufacturing a semiconductor light emitting device according to the eighth aspect, after the selective oxidation layer is grown, the growth of the GaInPAs layer, the GaInP layer, or the GaPAs layer is completed. Remove at least one of Al source, Al reactant, Al compound, Al remaining in the gas supply line or in the growth chamber where the nitrogen compound source or impurities contained in the nitrogen compound source come into contact The step of performing is characterized in that the growth is interrupted and the gas supply line or the growth chamber is purged with a carrier gas.
[0035]
According to a tenth aspect of the present invention, in the method for manufacturing a semiconductor light emitting device according to the eighth aspect, the susceptor is baked during the growth interruption.
[0036]
The invention according to claim 11 is the method of manufacturing a semiconductor light emitting device according to claim 8, wherein the nitrogen compound raw material or the nitrogen compound is formed after the growth of the selective oxidation layer and before the start of the growth of the active layer containing nitrogen. The step of removing at least one of the Al raw material, Al reactant, Al compound, and Al remaining in the gas supply line or the growth chamber where the impurities contained in the raw material come into contact with each other is performed by using an etching gas in the growth chamber. It is the process of supplying.
[0037]
According to a twelfth aspect of the present invention, in the method for manufacturing a semiconductor light emitting device according to the eighth aspect, the etching gas is an organic nitrogen compound gas.
[0038]
The invention according to claim 13 is the method for manufacturing a semiconductor light emitting device according to claim 8, wherein the etching gas is a gas containing oxygen (O).
[0039]
According to a fourteenth aspect of the present invention, in the method for manufacturing a semiconductor light emitting device according to the eighth aspect, the etching gas is a gas containing chlorine (Cl).
[0043]
  Also,Claim 15The described invention has a p-type semiconductor layer between an active layer containing nitrogen and a semiconductor substrate, and is arranged in the p-type semiconductor layerContains Al and AsIn the semiconductor light emitting device in which a part of the selective oxidation layer is selectively oxidized to form a current confinement structure, a band gap is larger between the selective oxidation layer and the active layer containing nitrogen than the active layer. A large semiconductor layer containing nitrogen is formed.
[0044]
  Also,Claim 16The invention described isClaim 15In the semiconductor light-emitting element described above, the semiconductor layer having a band gap larger than that of the active layer and containing nitrogen is any one of GaNAs, GaInNAs, GaInNP, GaNPAs, and GaInNPAs.
[0045]
  Also,Claim 17The invention described isClaim 15In the described semiconductor light emitting device, GaAs, GaInAs, GaAsP, GaInPAs, GaInP having a band gap larger than that of the active layer and having a band gap energy higher than that between the semiconductor layer containing nitrogen and the active layer containing nitrogen. A layer made of any one of the above is formed.
[0046]
  Also,Claim 18The described invention includes a resonator structure including an active region having an active layer containing nitrogen, and an upper reflecting mirror and a lower reflecting mirror provided above and below the active layer in order to obtain laser light. A method of manufacturing a surface-emitting type semiconductor laser device having a p-type semiconductor layer between an active layer and a semiconductor substrate, wherein the lower reflecting mirror periodically changes the refractive index and converts incident light into a light wave A semiconductor distributed Bragg reflector that reflects due to interference is included, and the semiconductor distributed Bragg reflector has a low refractive index layer made of Al._xGa_{1- x}The layer composed of As (0 <x ≦ 1) and having a large refractive index of the semiconductor distributed Bragg reflector is made of Al._yGa_{1- y}As (0 ≦ y <x ≦ 1) for selectively oxidizing a part of the p-type semiconductor layer for current confinementContains Al and AsA selective oxidation layer is formed, and at least one GaInPAs layer, GaInP layer, or GaPAs layer is formed between the selective oxidation layer and an active layer containing nitrogen, and the growth of the selective oxidation layer is performed After that, until the growth of the GaInPAs layer, the GaInP layer, or the GaPAs layer is completed, the nitrogen compound raw material or the impurity contained in the nitrogen compound raw material is in the gas supply line or in the growth chamber where the impurities come into contact. A step of removing at least one of the remaining Al raw material, Al reactant, Al compound, and Al is provided.
[0047]
  Also,Claim 19The invention described isClaim 18In the manufacturing method of the surface-emitting type semiconductor laser device described above, a place where the nitrogen compound raw material or impurities contained in the nitrogen compound raw material are in contact between the growth of the selective oxidation layer and the start of the growth of the active layer containing nitrogen The process of removing at least one of Al raw material, Al reactant, Al compound, and Al remaining in the gas supply line or in the growth chamber interrupts the growth and purges the gas supply line or the growth chamber with the carrier gas. It is the process to perform.
[0048]
  Also,Claim 20The invention described isClaim 19In the surface-emitting type semiconductor laser device manufacturing method described above, the susceptor is baked during the growth interruption.
[0050]
  Also,Claim 21The described invention includes a resonator structure including an active region having an active layer containing nitrogen, and an upper reflecting mirror and a lower reflecting mirror provided above and below the active layer in order to obtain laser light. A surface emitting semiconductor laser element having a p-type semiconductor layer between an active layer and a semiconductor substrate, wherein the lower reflecting mirror periodically changes the refractive index and reflects incident light by light wave interference. The semiconductor distributed Bragg reflector has a low refractive index layer made of Al._xGa_{1- x}The layer composed of As (0 <x ≦ 1) and having a large refractive index of the semiconductor distributed Bragg reflector is made of Al._yGa_{1- y}As (0 ≦ y <x ≦ 1) for selectively oxidizing a part of the p-type semiconductor layer for current confinementContains Al and AsIt has a selective oxidation layer, and a semiconductor layer having a band gap larger than that of the active layer and containing nitrogen is formed between the selective oxidation layer and the active layer containing nitrogen.
[0051]
  Also,Claim 22The invention described isClaim 21In the surface-emitting semiconductor laser device described above, the semiconductor layer having a band gap larger than that of the active layer and containing nitrogen is any one of GaNAs, GaInNAs, GaInNP, GaNPAs, and GaInNPAs.
[0052]
  Also,Claim 23The invention described isClaim 21In the surface-emitting type semiconductor laser device described above, GaAs, GaInAs, GaAsP, which has a band gap larger than that of the active layer and between the semiconductor layer containing nitrogen and the active layer containing nitrogen, which has a band gap energy larger than both. A layer made of any one of GaInPAs and GaInP is formed.
[0053]
  Also,Claim 24The invention described isClaims 21 to 23A surface emitting semiconductor laser array comprising a plurality of the surface emitting semiconductor laser elements according to any one of the above.
[0054]
  Also,Claim 25The invention described isClaims 21 to 23An optical transmission module in which the surface-emitting type semiconductor laser device according to any one of the above or the surface-emitting type semiconductor laser array according to claim 28 is used as a light source.
[0055]
  Also,Claim 26The invention described isClaims 21 to 23An optical transceiver module in which the surface-emitting type semiconductor laser device according to any one of the above or the surface-emitting type semiconductor laser array according to claim 28 is used as a light source.
[0056]
  Also,Claim 27The invention described isClaims 21 to 23An optical communication system in which the surface-emitting type semiconductor laser device according to any one of the above or the surface-emitting type semiconductor laser array according to claim 28 is used as a light source.
[0057]
  Also,Claim 28The invention described is a method of manufacturing a semiconductor light emitting device in which a semiconductor layer containing Al is provided between a substrate and an active layer, and after the semiconductor layer containing Al is grown, the active layer containing nitrogen Before starting the growth of the step, supplying a gas containing bromine as an etching gas into the growth chamber to remove at least one of the Al raw material, Al reactant, Al compound, and Al remaining in the growth chamber. It is characterized by providing.
[0058]
  Also,Claim 29The invention described is a method of manufacturing a semiconductor light emitting device in which a semiconductor layer containing Al is provided between a substrate and an active layer, and after the semiconductor layer containing Al is grown, the active layer containing nitrogen Before starting the growth of the substrate, the growth is interrupted once, and before re-growth, a gas containing bromine as an etching gas is supplied into the growth chamber to remove a part of the surface of the substrate to be grown. It is a feature.
[0059]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0060]
As described above, when an active layer containing nitrogen such as GaInNAs is continuously formed on a semiconductor layer containing Al as a constituent element using a single MOCVD apparatus, the emission intensity of the active layer deteriorates. Therefore, the threshold current density of the GaInNAs laser formed on the AlGaAs cladding layer is several times higher than that formed on the GaInP cladding layer.
[0061]
In particular, for example, in order to fabricate a surface emitting laser array, a p-type semiconductor layer is formed on a semiconductor substrate, and then an active layer containing nitrogen is formed. The p-type semiconductor layer is mainly selected from AlAs. In the case where an oxide layer is arranged and a part of the arranged selective oxidation layer is selectively oxidized to form a current confinement structure, an active layer containing nitrogen and a selective oxidation layer made of an AlAs-based material are provided. The structure is close, and the above result is extremely problematic (that is, the emission intensity of the active layer is deteriorated).
[0062]
Therefore, the inventor of the present application examined the elucidation of the cause of this problem.
[0063]
FIG. 5 shows an example of the semiconductor light-emitting device shown in FIG. 4, in which an element in which the cladding layer 202 is made of AlGaAs, the intermediate layer 203 is made of GaAs, and the active layer 204 is made of a GaInNAs / GaAs double quantum well structure is epitaxially grown. It is a figure which shows the depth direction distribution of nitrogen (N) density | concentration and oxygen (O) density | concentration when it forms using an apparatus (MOCVD). This measurement was performed by SIMS. The measurement conditions are shown in the following table (Table 1).
[0064]
[Table 1]

[0065]
In FIG. 5, two nitrogen peaks are seen in the active layer 204 corresponding to the GaInNAs / GaAs double quantum well structure. In the active layer 204, an oxygen peak is detected. However, the oxygen concentration in the intermediate layer 203 not containing N and Al is about one digit lower than the oxygen concentration in the active layer 204.
[0066]
On the other hand, when the depth distribution of oxygen concentration is measured for a semiconductor light emitting device in which the cladding layer 202 is made of GaInP, the intermediate layer 203 is made of GaAs, and the active layer 204 is made of a GaInNAs / GaAs double quantum well structure, The oxygen concentration in layer 204 was at the background level.
[0067]
That is, a semiconductor in which an Al-containing semiconductor layer (202) is provided between a substrate (201) and a nitrogen-containing active layer (204) using a nitrogen compound raw material and an organometallic Al raw material by one epitaxial growth apparatus. It has been clarified by experiments of the inventors of the present application that oxygen is taken into the active layer (204) containing nitrogen when the crystal of the light emitting element is continuously grown. Oxygen taken into the active layer (204) forms a non-radiative recombination level, which decreases the light emission efficiency of the active layer (204). Oxygen incorporated into the active layer (204) decreases the light emission efficiency in the semiconductor light emitting device in which the semiconductor layer (202) containing Al is provided between the substrate (201) and the active layer (204) containing nitrogen. It was newly found that this is the cause. The origin of oxygen is considered to be a substance containing oxygen remaining in the apparatus or a substance containing oxygen contained as an impurity in the nitrogen compound raw material.
[0068]
Next, the cause of oxygen uptake was examined. FIG. 6 is a diagram showing a depth direction distribution of Al concentration of the same sample as FIG. The measurement was performed by SIMS. The measurement conditions are shown in the following table (Table 2).
[0069]
[Table 2]

[0070]
From FIG. 6, Al is detected in the active layer 204 which is not originally introduced with the Al raw material. However, in the intermediate layer (GaAs layer) 203 adjacent to the semiconductor layers (cladding layers) 202 and 205 containing Al, the Al concentration is about one digit lower than that of the active layer 204. This indicates that Al in the active layer 204 is not mixed by diffusion and substitution from the semiconductor layers (cladding layers) 202 and 205 containing Al.
[0071]
On the other hand, when an active layer containing nitrogen was grown on a semiconductor layer not containing Al, such as GaInP, Al was not detected in the active layer.
[0072]
Therefore, the Al detected in the active layer 204 in FIG. 6 is that at least one of the Al source, Al reactant, Al compound, and Al remaining in the growth chamber or gas supply line is a nitrogen compound source or nitrogen compound source. It is incorporated into the active layer 204 by combining with impurities (such as moisture) therein. That is, when using a nitrogen compound raw material and an organometallic Al raw material, a single crystal growth apparatus continuously crystal-grows a semiconductor light emitting device in which an Al-containing semiconductor layer is provided between a substrate and an active layer containing nitrogen. It has been newly found by the inventors of the present application that Al is naturally taken up in the active layer containing nitrogen.
[0073]
Compared with the depth distribution of nitrogen and oxygen concentration in the same element shown in FIG. 5, the two oxygen peak profiles in the double quantum well active layer 204 do not correspond to the peak profile of nitrogen concentration, This corresponds to the Al concentration profile of FIG. From this, it was clarified that oxygen impurities in the GaInNAs well layer were incorporated together with Al incorporated in the well layer rather than being incorporated with the nitrogen source. . That is, when at least one of Al raw material, Al reactant, Al compound, and Al remaining in the growth chamber comes into contact with the nitrogen compound raw material, it remains in the moisture contained in the Al and nitrogen compound raw material or in the gas line or reaction chamber. Al and oxygen are taken into the active layer 204 by combining with oxygen-containing substances such as moisture. It has become clear for the first time through experiments by the inventors of the present application that oxygen taken into the active layer 204 reduces the luminous efficiency of the active layer 204.
[0074]
In the case of being produced by a normal MBE method, there has been no report on a decrease in light emission efficiency in a semiconductor light emitting device in which a semiconductor layer containing Al is provided between a substrate and an active layer containing nitrogen.
[0075]
This is because the MBE method performs crystal growth at an ultra-low pressure (in a high vacuum), whereas the MOCVD method is usually several tens of Torr to atmospheric pressure, and the pressure in the reaction chamber is higher than the MBE method. This is probably because the free path is overwhelmingly short, and the supplied raw material, carrier gas, etc. contact and react with the Al-based residue in the reaction chamber or the like.
[0076]
Therefore, in the case of a growth method such as the MOCVD method in which the pressure in the reaction chamber or the gas line is high, in order to improve this, at least Al remaining in the apparatus is contained in the film together with oxygen during the active layer growth including nitrogen. It was found that it was necessary to provide a step for removing the Al-based residue so as not to be taken in.
[0077]
The present invention has a structure in which an active layer containing nitrogen is formed after forming a p-type semiconductor layer, a selective oxidation layer mainly composed of AlAs is arranged in the p-type semiconductor layer, and the selective oxidation layer arranged When producing a semiconductor light emitting device that selectively oxidizes a part of the electrode to form a current confinement structure, Al remaining in the device is not taken into the film together with oxygen during the growth of the active layer containing nitrogen. Is intended to be.
[0078]
First embodiment
For this reason, the method for manufacturing a semiconductor light emitting device according to the first embodiment of the present invention has a p-type semiconductor layer between an active layer containing nitrogen and a semiconductor substrate, and AlAs is the main component in the p-type semiconductor layer. A method of manufacturing a semiconductor light emitting device, wherein a selective confined oxide layer is disposed and a part of the disposed selective oxidized layer is selectively oxidized to form a current confinement structure, wherein the selective oxidized layer is grown In the gas supply line or in the growth chamber where the nitrogen compound raw material or impurities contained in the nitrogen compound raw material come into contact before the start of the growth of the active layer containing nitrogen, Al raw material, Al reactant, Al compound remaining in the growth chamber , A step of removing at least one of Al is provided.
[0079]
As described above, a selective oxidation layer having a p-type semiconductor layer between an active layer containing nitrogen and a semiconductor substrate and having a selective oxidation layer mainly composed of AlAs in the p-type semiconductor layer is disposed. In a method of manufacturing a semiconductor light emitting device in which a part of an oxide layer is selectively oxidized to form a current confinement structure, an oxygen-based active layer (nitrogen-containing active layer) in which Al residue causes non-radiative recombination As in the first embodiment, after the formation of the Al-containing layer and before the growth of the active layer containing nitrogen, the reaction chamber side wall, the heating zone, and the substrate are formed. Incorporation of oxygen into the active layer can be suppressed by providing a step of removing the Al-based residue remaining in the jig or the like that holds the material.
[0080]
By the method of the first embodiment of the present invention, the Al concentration in the active layer containing nitrogen is set to 1 × 10.¹⁹cm^-3It becomes possible to reduce to the following, and thereby, the room-temperature continuous oscillation of the semiconductor light emitting element becomes possible. Furthermore, the Al concentration in the active layer containing nitrogen is set to 2 × 10.¹⁸cm^-3When reduced to the following, light emission characteristics equivalent to those formed on a semiconductor layer not containing Al can be obtained.
[0081]
The following table (Table 3) shows the results of evaluating the threshold current density by fabricating a broad stripe laser using AlGaAs as a cladding layer (a layer containing Al) and a GaInNAs double quantum well structure (a layer containing nitrogen) as an active layer. Is shown.
[0082]
[Table 3]

[0083]
From Table 3, in the structure in which the active layer containing nitrogen is continuously formed in the semiconductor layer containing Al as a constituent element, 2 × 10¹⁹cm^-3If the above Al is included, 1 × 10¹⁸cm^-3More oxygen is taken in, and the threshold current density is 10 kA / cm²This is a remarkably high value. In contrast, the Al concentration in the active layer is 1 × 10.¹⁹cm^-3By reducing to the following, the oxygen concentration in the active layer becomes 1 × 10¹⁸cm^-3Reduced to a threshold current density of 2-3 kA / cm²The broad stripe laser oscillated. Broad stripe laser threshold current density is several kA / cm²Continuous oscillation at room temperature is possible with the following active layer quality. Therefore, the Al concentration in the active layer containing nitrogen is set to 2 × 10.¹⁹cm^-3By suppressing to the following, a semiconductor laser capable of continuous oscillation at room temperature can be manufactured.
[0084]
As described above, in the present invention, a p-type semiconductor layer is provided between an active layer containing nitrogen and a semiconductor substrate, and a selective oxidation layer mainly composed of AlAs is disposed in the p-type semiconductor layer. A method of manufacturing a semiconductor light emitting device, wherein a part of the selectively oxidized layer is selectively oxidized to form a current confinement structure, between the growth of the selectively oxidized layer and the start of the growth of the active layer containing nitrogen And removing at least one of the Al source material, Al reactant, Al compound, and Al remaining in the gas supply line or the growth chamber where the nitrogen compound source material or impurities contained in the nitrogen compound source come into contact Therefore, the incorporation of oxygen during the growth of the active layer containing nitrogen can be reduced, and even in a semiconductor light emitting device in which the active layer containing nitrogen is formed on the upper part of the semiconductor layer containing Al, the luminous efficiency is improved. Reduce The semiconductor light-emitting element can be grown without the.
[0085]
In the method of manufacturing the semiconductor light emitting device according to the first embodiment of the present invention described above, the Al source material remaining in the nitrogen supply source or in the gas supply line where the impurities contained in the nitrogen source material come into contact or in the growth chamber. The step of removing at least one of Al reactant, Al compound, and Al can be performed by interrupting the growth and purging the gas supply line or the growth chamber with a carrier gas.
[0086]
That is, as described above, the Al-based residue causes oxygen that causes non-radiative recombination to be incorporated into the active layer (the active layer containing nitrogen), so that after the growth of the semiconductor layer containing Al, The Al remaining in the reaction chamber side wall, the heating zone, the jig for holding the substrate, etc. by interrupting the growth and purging by supplying a carrier gas before the growth of the active layer containing nitrogen. System residues can be removed, and oxygen uptake into the active layer can be suppressed. Usually, in MOCVD, hydrogen (H₂) Gas is used, but nitrogen gas (N₂An inert gas such as) can also be used. Further, since the growth is interrupted, oxygen (O) will be observed at the interface where the growth is interrupted by SIMS analysis.
[0087]
Also, the susceptor can be baked during the growth interruption.
[0088]
That is, by heating the susceptor, Al-based residue remaining on the reaction chamber side wall, heating zone, jig for holding the substrate, etc. is easily evaporated and reacted, so the effect of removing the Al-based residue is effective. Get higher. In addition, since the crystal growth is performed by heating the susceptor, the growth may be interrupted and heated in the same manner. Therefore, the susceptor can be easily baked during the growth interruption. At this time, the baking temperature is preferably higher than the temperature during crystal growth. Further, the substrate to be grown may be moved to a separate chamber, or may be performed as it is without moving to the separate chamber. When the process is performed as it is, it is preferable to supply a group V raw material in order to prevent the group V element from evaporating and desorbing from the growth target substrate.
[0089]
Further, in the method for manufacturing the semiconductor light emitting device according to the first embodiment described above, it is contained in the nitrogen compound raw material or the nitrogen compound raw material after the growth of the selective oxidation layer and before the start of the growth of the active layer containing nitrogen. An etching gas can also be supplied to the growth chamber to remove at least one of the Al source, Al reactant, Al compound, and Al remaining in the gas supply line where the impurities come into contact or in the growth chamber. .
[0090]
That is, after the growth of the semiconductor layer containing Al and before the growth of the active layer containing nitrogen, it reacts with the Al-based residue remaining on the reaction chamber side wall, heating zone, jig holding the substrate, etc. By supplying a gas (etching gas) that can be removed to the reaction chamber, oxygen uptake into the active layer can be suppressed, and a semiconductor light-emitting element with high emission efficiency can be manufactured.
[0091]
An organic nitrogen compound gas can be used as a gas (etching gas) that can be removed by reacting with the Al-based residue. Here, as the organic nitrogen compound gas, DMHy gas can be cited, and when an active layer containing nitrogen is grown as described above, DMHy gas, which is one of organic nitrogen compound gases, is reacted using a DMHy cylinder. When supplied to the chamber, it reacts with the Al-based residue, and the Al-based residue can be removed.
[0092]
As described above, when the organic nitrogen compound gas is supplied after the growth of the semiconductor layer containing Al and before the growth of the active layer containing nitrogen, the organic nitrogen compound gas is supplied to the reaction chamber side wall, the heating zone, It reacts with the Al-based residue remaining on the jig or the like that holds the substrate, and the Al-based residue can be removed, whereby the oxygen uptake into the active layer can be suppressed. Further, it is preferable to use the same gas as the nitrogen source of the active layer containing nitrogen as the etching gas because it is not necessary to add a special gas line.
[0093]
Alternatively, a gas containing oxygen (O) can be used as the etching gas. That is, as a gas (etching gas) that can be removed by reacting with an Al-based residue,₂, H₂A gas containing oxygen such as O can also be used.
[0094]
As described above, it is known that oxygen is taken into the active layer together with Al during the growth of the active layer containing nitrogen. Therefore, O₂, H₂It can be seen that a gas containing oxygen such as O reacts with an Al-based residue. As a result, after the growth of the semiconductor layer containing Al and before the growth of the active layer containing nitrogen, O₂, H₂When a gas containing oxygen such as O is supplied, this gas reacts with the Al residue remaining on the reaction chamber side wall, heating zone, jig holding the substrate, etc., and removes the Al residue. Thus, the oxygen uptake into the active layer can be suppressed. As can be seen from the SIMS profile in FIG. 6, a large amount of Al is taken into the first layer of the active layer containing nitrogen and hardly taken into the second layer. Al-based residues can be removed simply by supplying the contained gas. Of course, it is necessary to remove the excessively supplied oxygen-containing gas before the growth of the active layer, so it is desirable to supply an appropriate amount that does not excessively increase (reversely, it is difficult to exclude the oxygen-containing gas). Because it becomes).
[0095]
Alternatively, a gas containing chlorine (Cl) can be used as the etching gas. For example, a chlorine-based compound gas such as HCl has an effect of etching away by reacting with reaction product deposits in the growth chamber. Therefore, if the chlorine-based compound gas is supplied after the growth of the semiconductor layer containing Al and before the growth of the active layer containing nitrogen, the chlorine-based compound gas holds the reaction chamber side wall, the heating zone, and the substrate. By reacting with the Al-based residue remaining on the jig or the like to be removed, the Al-based residue can be removed, and thereby, oxygen uptake into the active layer can be suppressed. Note that HCl gas can be used by filling a gas cylinder. In this case, in order to prevent corrosion of the metal portion inside the apparatus by the chlorine-based gas, a high-purity material with less oxygen, moisture, etc. is preferable.
[0096]
Second embodiment
The method for manufacturing a semiconductor light-emitting device according to the second embodiment of the present invention includes a p-type semiconductor layer between an active layer containing nitrogen and a semiconductor substrate, and the p-type semiconductor layer contains AlAs as a main component. A selective oxidation layer is disposed, a portion of the disposed selective oxidation layer is selectively oxidized to form a current confinement structure, and at least one layer is formed between the selective oxidation layer and the active layer containing nitrogen. A method of manufacturing a semiconductor light emitting device for forming a GaInPAs layer, a GaInP layer, or a GaPAs layer, wherein the growth of the selectively oxidized layer is followed by the growth of the GaInPAs layer, the GaInP layer, or the GaPAs layer. Until completion, the Al raw material, Al reactant, Al compound, Al remaining in the nitrogen supply or the gas supply line where the impurities contained in the nitrogen raw material come into contact or in the growth chamber Out of it is characterized by providing a step of removing at least one.
[0097]
In the second embodiment, growth is interrupted outside the active region where carriers are not injected to remove the Al-based residue, resulting in non-radiative recombination caused by residual Al or an Al-based residue removal step. It can suppress that luminous efficiency falls by nonluminous recombination.
[0098]
In the method for manufacturing a semiconductor light emitting device according to the second embodiment of the present invention described above, the Al raw material remaining in the nitrogen compound raw material or in the gas supply line where the impurities contained in the nitrogen compound raw material come into contact or in the growth chamber The step of removing at least one of Al reactant, Al compound and Al can be performed by interrupting the growth and purging the gas supply line or the growth chamber with a carrier gas.
[0099]
That is, as described above, since the Al-based residue causes oxygen that causes non-radiative recombination to be taken into the active layer (the active layer containing nitrogen), the Al-containing semiconductor layer is grown after the growth. The Al remaining in the reaction chamber side wall, the heating zone, the jig for holding the substrate, etc. by interrupting the growth and purging by supplying a carrier gas before the growth of the active layer containing nitrogen. System residues can be removed, and oxygen uptake into the active layer can be suppressed. Usually, in MOCVD, hydrogen (H₂) Gas is used, but nitrogen gas (N₂An inert gas such as) can also be used. Further, since the growth is interrupted, oxygen (O) will be observed at the interface where the growth is interrupted by SIMS analysis.
[0100]
Also, the susceptor can be baked during the growth interruption.
[0101]
That is, by heating the susceptor, Al-based residue remaining on the reaction chamber side wall, heating zone, jig for holding the substrate, etc. is easily evaporated and reacted, so the effect of removing the Al-based residue is effective. Get higher. In addition, since the crystal growth is performed by heating the susceptor, the growth may be interrupted and heated in the same manner. Therefore, the susceptor can be easily baked during the growth interruption. At this time, the baking temperature is preferably higher than the temperature during crystal growth. Further, the substrate to be grown may be moved to a separate chamber, or may be performed as it is without moving to the separate chamber. When the process is performed as it is, it is preferable to supply a group V raw material in order to prevent the group V element from evaporating and desorbing from the growth target substrate.
[0102]
Further, in the method for manufacturing the semiconductor light emitting device of the second embodiment described above, it is contained in the nitrogen compound raw material or the nitrogen compound raw material between the growth of the selective oxidation layer and the start of the growth of the active layer containing nitrogen. An etching gas can also be supplied to the growth chamber to remove at least one of the Al source, Al reactant, Al compound, and Al remaining in the gas supply line where the impurities come into contact or in the growth chamber. .
[0103]
That is, after the growth of the semiconductor layer containing Al and before the growth of the active layer containing nitrogen, it reacts with the Al-based residue remaining on the reaction chamber side wall, heating zone, jig holding the substrate, etc. By supplying a gas (etching gas) that can be removed to the reaction chamber, oxygen uptake into the active layer can be suppressed, and a semiconductor light-emitting element with high emission efficiency can be manufactured.
[0104]
An organic nitrogen compound gas can be used as a gas (etching gas) that can be removed by reacting with the Al-based residue. Here, as the organic nitrogen compound gas, DMHy gas can be cited, and when an active layer containing nitrogen is grown as described above, DMHy gas, which is one of organic nitrogen compound gases, is reacted using a DMHy cylinder. When supplied to the chamber, it reacts with the Al-based residue, and the Al-based residue can be removed.
[0105]
As described above, when the organic nitrogen compound gas is supplied after the growth of the semiconductor layer containing Al and before the growth of the active layer containing nitrogen, the organic nitrogen compound gas is supplied to the reaction chamber side wall, the heating zone, It reacts with the Al-based residue remaining on the jig or the like that holds the substrate, and the Al-based residue can be removed, whereby the oxygen uptake into the active layer can be suppressed. Further, it is preferable to use the same gas as the nitrogen source of the active layer containing nitrogen as the etching gas because it is not necessary to add a special gas line.
[0106]
Alternatively, a gas containing oxygen (O) can be used as the etching gas. That is, as a gas (etching gas) that can be removed by reacting with an Al-based residue,₂, H₂A gas containing oxygen such as O can also be used.
[0107]
As described above, it is known that oxygen is taken into the active layer together with Al during the growth of the active layer containing nitrogen. Therefore, O₂, H₂It can be seen that a gas containing oxygen such as O reacts with an Al-based residue. As a result, after the growth of the semiconductor layer containing Al and before the growth of the active layer containing nitrogen, O₂, H₂When a gas containing oxygen such as O is supplied, this gas reacts with the Al residue remaining on the reaction chamber side wall, heating zone, jig holding the substrate, etc., and removes the Al residue. Thus, the oxygen uptake into the active layer can be suppressed. As can be seen from the SIMS profile in FIG. 6, a large amount of Al is taken into the first layer of the active layer containing nitrogen and hardly taken into the second layer. Al-based residues can be removed simply by supplying the contained gas. Of course, it is necessary to remove the excessively supplied oxygen-containing gas before the growth of the active layer, so it is desirable to supply an appropriate amount that does not excessively increase (reversely, it is difficult to exclude the oxygen-containing gas). Because it becomes).
[0108]
Alternatively, a gas containing chlorine (Cl) can be used as the etching gas. For example, a chlorine-based compound gas such as HCl has an effect of etching away by reacting with reaction product deposits in the growth chamber. Therefore, if the chlorine-based compound gas is supplied after the growth of the semiconductor layer containing Al and before the growth of the active layer containing nitrogen, the chlorine-based compound gas holds the reaction chamber side wall, the heating zone, and the substrate. By reacting with the Al-based residue remaining on the jig or the like to be removed, the Al-based residue can be removed, and thereby, oxygen uptake into the active layer can be suppressed. Note that HCl gas can be used by filling a gas cylinder. In this case, in order to prevent corrosion of the metal part inside the apparatus due to the chlorine-based gas, a high-purity material with less oxygen, moisture and the like is preferable.
[0109]
Third embodiment
The semiconductor light emitting device according to the third embodiment of the present invention has a p-type semiconductor layer between an active layer containing nitrogen and a semiconductor substrate, and has AlAs disposed in the p-type semiconductor layer as a main component. A semiconductor light emitting device in which a part of a selective oxidation layer to be selectively oxidized is formed to form a current confinement structure, wherein at least one GaInPAs is interposed between the selective oxidation layer and an active layer containing nitrogen. A layer, a GaInP layer, or a GaPAs layer is formed.
[0110]
As described above, the surface of the substrate to be grown is oxidized or otherwise removed by providing a step for removing the Al-based residue remaining on the reaction chamber side wall, heating zone, jig for holding the substrate, etc. during crystal growth. May cause defects on the surface of the substrate to be grown. If the place (region) where the defect occurs is an active region where carriers are injected, the defect becomes a non-light-emitting recombination center and the light emission efficiency may be lowered during the operation of the light emitting element.
[0111]
On the other hand, a GaInPAs layer, a GaInP layer, or a GaPAs layer having a band gap energy higher than the band gap energy of the surface material at the time of removing the Al-based residue, an active layer containing a selective oxidation layer and nitrogen, When it grows during this period, almost no carriers are injected into the surface when removing Al-based residues, preventing defects from becoming non-radiative recombination centers and reducing luminous efficiency during operation of the light-emitting device. it can. Of course, the GaInPAs layer, the GaInP layer, or the GaPAs layer may contain other III-V group materials such as B, Tl, and Sb.
[0112]
It is to be noted that while crystal growth of such a semiconductor light emitting device is performed, the Al raw material, Al reactant, Al remaining in the gas supply line or in the growth chamber where the nitrogen compound raw material or impurities contained in the nitrogen compound raw material come into contact A step of removing at least one of the compound and Al with an organic nitrogen compound gas can be performed. For example, when an organic nitrogen compound gas such as DMHy, which is an etching gas, is supplied when growing a layer not containing Al between the semiconductor layer containing Al and an active layer containing nitrogen, a form that takes in Al and oxygen. A semiconductor layer containing nitrogen is grown. As a result, at least one of the Al raw material, the Al reactant, the Al compound, and Al remaining in the gas supply line or in the growth chamber where the nitrogen compound raw material or impurities contained in the nitrogen compound raw material come into contact can be removed. Therefore, oxygen uptake into the active layer can be suppressed. In this case, it is necessary to set conditions so that the semiconductor layer containing nitrogen has a larger band gap than the band gap of the active layer. For example, DMHy gas phase ratio: [DMHy] / ([DMHy] + [AsH₃]) Is reduced, the growth temperature is increased, and the In composition is increased, the incorporation of nitrogen is reduced. If this semiconductor layer containing nitrogen is analyzed by SIMS, oxygen (O) or Al will be observed in addition to nitrogen.
[0113]
Fourth embodiment
The semiconductor light emitting device according to the fourth embodiment of the present invention has a p-type semiconductor layer between an active layer containing nitrogen and a semiconductor substrate, and has AlAs disposed in the p-type semiconductor layer as a main component. In a semiconductor light emitting device in which a part of the selectively oxidized layer to be selectively oxidized is formed to form a current confinement structure, a band gap is larger than the active layer between the selectively oxidized layer and the active layer containing nitrogen. And a semiconductor layer containing nitrogen is formed.
[0114]
It is to be noted that while crystal growth of such a semiconductor light emitting device is performed, the Al raw material, Al reactant, Al remaining in the gas supply line or in the growth chamber where the nitrogen compound raw material or impurities contained in the nitrogen compound raw material come into contact A step of removing at least one of the compound and Al with an organic nitrogen compound gas can be performed. For example, when an organic nitrogen compound gas such as DMHy, which is an etching gas, is supplied when growing a layer not containing Al between the semiconductor layer containing Al and an active layer containing nitrogen, a form that takes in Al and oxygen. A semiconductor layer containing nitrogen is grown. As a result, at least one of the Al raw material, the Al reactant, the Al compound, and Al remaining in the gas supply line or in the growth chamber where the nitrogen compound raw material or impurities contained in the nitrogen compound raw material come into contact can be removed. Therefore, oxygen uptake into the active layer can be suppressed. In this case, it is necessary to set conditions so that the semiconductor layer containing nitrogen has a larger band gap than the band gap of the active layer. For example, DMHy gas phase ratio: [DMHy] / ([DMHy] + [AsH₃]) Is reduced, the growth temperature is increased, and the In composition is increased, the incorporation of nitrogen is reduced. If this semiconductor layer containing nitrogen is analyzed by SIMS, oxygen (O) or Al will be observed in addition to nitrogen.
[0115]
In the semiconductor light emitting device of the fourth embodiment, as the semiconductor layer having a band gap larger than that of the active layer and containing nitrogen, GaNAs, GaInNAs, GaInNP, GaNPAs, GaInNPAs, or the like can be used. Of course, other group III-V materials such as Sb, B, and Tl may be included.
[0116]
In the semiconductor light emitting device of the fourth embodiment, GaAs, which has a band gap larger than that of the active layer and between the semiconductor layer containing nitrogen and the active layer containing nitrogen, has a band gap energy larger than both. A layer made of any one of GaInAs, GaAsP, GaInPAs, and GaInP may be formed.
[0117]
In other words, since the band gap is larger than that of the active layer and oxygen is taken into the semiconductor layer containing nitrogen, if this layer is in the active region where carriers are injected, it becomes a non-radiative recombination center. There is a possibility that the light emission efficiency may be lowered during operation of the light emitting element. On the other hand, a layer made of any one of GaAs, GaInAs, GaInPAs, GaInP, and GaPAs having a band gap energy higher than the band gap energy of the surface material at the time of removing the Al-based residue is combined with an active layer containing nitrogen. When grown in the meantime, since the band gap is larger than that of the active layer and almost no carriers are injected into the semiconductor layer containing nitrogen, the light emission efficiency is not lowered due to the above cause.
[0118]
Fifth embodiment
A method for manufacturing a surface-emitting type semiconductor laser device according to a fifth embodiment of the present invention includes an active region having an active layer containing nitrogen, and upper reflectors provided above and below the active layer to obtain laser light. And a surface emitting semiconductor laser device having a resonator structure including a lower reflecting mirror and having a p-type semiconductor layer between an active layer containing nitrogen and a semiconductor substrate, the lower reflecting The mirror includes a semiconductor distributed Bragg reflector that periodically changes the refractive index and reflects incident light by light wave interference. The layer having a small refractive index of the semiconductor distributed Bragg reflector is made of Al._xGa_{1- x}The layer composed of As (0 <x ≦ 1) and having a large refractive index of the semiconductor distributed Bragg reflector is made of Al._yGa_{1- y}A selective oxidation layer composed of As (0 ≦ y <x ≦ 1), mainly composed of AlAs for selectively confining a part of the p-type semiconductor layer to perform current confinement, At least one GaInPAs layer or GaInP layer or GaPAs layer is formed between the oxide layer and the active layer containing nitrogen, and after the selective oxidation layer is grown, the GaInPAs layer or GaInP layer Or the Al source, Al reactant, Al remaining in the gas supply line or in the growth chamber where the nitrogen compound raw material or impurities contained in the nitrogen compound raw material come into contact until the growth of the GaPAs layer is completed A step of removing at least one of the compound and Al is provided.
[0119]
One specific method for suppressing the incorporation of oxygen into the active layer of the surface emitting semiconductor laser device is to grow a GaInPAs layer, a GaInP layer, or a GaPAs layer after the growth of the selective oxidation layer. In this case, the growth is interrupted until the process is completed, and a step of removing at least one of the Al raw material, Al reactant, Al compound, and Al remaining in the gas supply line or the growth chamber is performed. As a result, the incorporation of oxygen into the active layer containing nitrogen is suppressed, and the influence of non-radiative recombination due to defects formed by interrupting the growth is avoided, so that the driving voltage is low and the light emission is low. A surface-emitting semiconductor laser device with high efficiency, low threshold current operation, and good temperature characteristics can be easily realized at low cost. Since the growth is interrupted, oxygen (O) will be observed by SIMS analysis of this growth interrupted interface.
[0120]
In addition, the susceptor can be baked during the growth interruption.
[0121]
That is, by heating the susceptor, Al-based residues remaining on the reaction chamber side wall, the heating zone, the jig for holding the substrate, and the like are easily evaporated and reacted, so the effect of removing is enhanced. Further, since the crystal growth is performed by heating the susceptor, the growth may be interrupted and heated in the same manner. Therefore, the susceptor can be easily baked during the growth interruption. At this time, the baking temperature is preferably higher than the temperature during crystal growth. Further, the substrate to be grown may be moved to a separate chamber, or may be performed as it is without moving to the separate chamber. When the process is performed as it is, it is preferable to supply a group V raw material in order to prevent the group V element from evaporating and desorbing from the growth target substrate.
[0122]
Sixth embodiment
A surface-emitting type semiconductor laser device according to the sixth embodiment of the present invention includes an active region having an active layer containing nitrogen, upper reflectors provided above and below the active layer to obtain laser light, and A surface-emitting semiconductor laser device having a resonator structure including a lower reflector and having a p-type semiconductor layer between an active layer containing nitrogen and a semiconductor substrate, wherein the lower reflector is refracted Including a semiconductor distributed Bragg reflector that periodically changes the rate and reflects incident light by light wave interference, and the layer having a low refractive index of the semiconductor distributed Bragg reflector is made of Al_xGa_{1- x}The layer composed of As (0 <x ≦ 1) and having a large refractive index of the semiconductor distributed Bragg reflector is made of Al._yGa_{1- y}A selective oxidation layer composed of As (0 ≦ y <x ≦ 1), mainly composed of AlAs for selectively confining a part of the p-type semiconductor layer to perform current confinement, It is characterized in that at least one GaInPAs layer, GaInP layer, or GaPAs layer is formed between the oxide layer and the active layer containing nitrogen.
[0123]
Here, for the active layer containing nitrogen, GaNAs, GaInNAs, InNAs, GaAsNSb, GaInNAsSb, GaNPAs, GaInNPAs, InNPAs, GaAsNPSb, GaInNPAsSb, and the like can be used. For example, the case where GaInNAs is used will be described below. GaInNAs can be lattice-matched to GaAs by adding N to GaInAs, which has a larger lattice constant than GaAs, and its band gap is reduced, and light emission in the 1.3 μm and 1.55 μm bands is achieved. It becomes possible. In addition, since the lattice matching system is a GaAs substrate, wide gap AlGaAs or GaInP can be used for the cladding layer.
[0124]
In addition, the addition of N reduces the band gap as described above, lowers the energy levels of both the conduction band and the valence band, and extremely increases the band discontinuity of the conduction band at the heterojunction. Temperature dependence can be made extremely small.
[0125]
Further, the surface emitting semiconductor laser element is advantageous for performing parallel transmission by downsizing, low power consumption, and two-dimensional integration. Although it is difficult to obtain a surface-emitting type semiconductor laser device that can withstand practical use in the conventional GaInPAs / InP system, a 0.85 μm band surface emitting semiconductor laser device using a GaAs substrate is used according to a GaInNAs-based material. Al (Ga) As / (Al) GaAs-based semiconductor multilayer distributed Bragg reflectors and the current narrowing structure by selective oxidation of AlAs can be applied, so that practical application can be expected.
[0126]
To achieve this, it is important to improve the crystal quality of the GaInNAs active layer, to reduce the resistance of the multilayer reflector, and to improve the crystal quality and controllability of the multilayer structure as a surface emitting semiconductor laser device. However, at least one GaInPAs layer, GaInP layer, or GaPAs layer is formed between the selective oxidation layer containing AlAs as a main component and the active layer containing nitrogen, thereby producing the present invention. The method can be applied easily, oxygen uptake into the active layer containing nitrogen is suppressed, low resistance, low driving voltage, high luminous efficiency, low threshold current operation, surface emission with good temperature characteristics Type semiconductor laser device can be easily realized at low cost. Further, according to the configuration of the surface emitting semiconductor laser element, a p-type substrate can be used.
[0127]
Seventh embodiment
A surface-emitting type semiconductor laser device according to a seventh embodiment of the present invention includes an active region having an active layer containing nitrogen, an upper reflector provided above and below the active layer to obtain laser light, and A surface-emitting semiconductor laser device having a resonator structure including a lower reflector and having a p-type semiconductor layer between an active layer containing nitrogen and a semiconductor substrate, wherein the lower reflector is refracted Including a semiconductor distributed Bragg reflector that periodically changes the rate and reflects incident light by light wave interference, and the layer having a low refractive index of the semiconductor distributed Bragg reflector is made of Al_xGa_{1- x}The layer composed of As (0 <x ≦ 1) and having a large refractive index of the semiconductor distributed Bragg reflector is made of Al._yGa_{1- y}A selective oxidation layer composed of As (0 ≦ y <x ≦ 1), mainly composed of AlAs for selectively confining a part of the p-type semiconductor layer to perform current confinement, A semiconductor layer having a band gap larger than that of the active layer and containing nitrogen is formed between the oxide layer and the active layer containing nitrogen.
[0128]
For example, when an organic nitrogen compound gas such as DMHy, which is an etching gas, is supplied when growing a layer not containing Al between the semiconductor layer containing Al and an active layer containing nitrogen, a form that takes in Al and oxygen. A semiconductor layer containing nitrogen is grown. As a result, at least one of the Al raw material, Al reactant, Al compound, and Al remaining in the growth chamber can be removed, so that oxygen incorporation into the active layer can be suppressed. In this case, it is necessary to set conditions so that the semiconductor layer containing nitrogen has a larger band gap than the band gap of the active layer. For example, DMHy gas phase ratio: [DMHy] / ([DMHy] + [AsH₃]) Is reduced, the growth temperature is increased, and the In composition is increased, the incorporation of nitrogen is reduced. If the semiconductor layer containing nitrogen is analyzed by SIMS, oxygen (O) or Al will be observed in addition to nitrogen.
[0129]
As a result, the incorporation of oxygen into the active layer containing nitrogen is suppressed, and the influence of non-radiative recombination due to defects formed by interrupting the growth is avoided, so that the driving voltage is low and the light emission is low. A surface-emitting semiconductor laser device with high efficiency, low threshold current operation, and good temperature characteristics can be easily realized at low cost. Further, according to the configuration of the surface emitting semiconductor laser element, a p-type substrate can be used.
[0130]
In the surface-emitting type semiconductor laser device of the seventh embodiment, GaNAs, GaInNAs, GaInNP, GaNPAs, GaInNPAs, or the like can be used as the semiconductor layer having a band gap larger than that of the active layer and containing nitrogen. Of course, other group III-V materials such as Sb, B, and Tl may be included.
[0131]
In the surface-emitting type semiconductor laser device of the seventh embodiment, the band gap is larger than that of the active layer and between the semiconductor layer containing nitrogen and the active layer containing nitrogen, the band gap energy is larger than both. A layer made of any one of large GaAs, GaInAs, GaAsP, GaInPAs, and GaInP may be formed.
[0132]
In other words, since the band gap is larger than that of the active layer and oxygen is taken into the semiconductor layer containing nitrogen, if this layer is in the active region where carriers are injected, it becomes a non-radiative recombination center. There is a possibility that the light emission efficiency may be lowered when the light emitting element is operated. On the other hand, a layer made of any one of GaAs, GaInAs, GaInPAs, GaInP, and GaPAs having a band gap energy higher than the band gap energy of the surface material at the time of removing the Al-based residue is combined with an active layer containing nitrogen. When grown in the meantime, since the band gap is larger than that of the active layer and almost no carriers are injected into the semiconductor layer containing nitrogen, the light emission efficiency is not lowered due to the above-mentioned causes.
[0133]
Eighth embodiment
The surface emitting semiconductor laser array according to the eighth embodiment of the present invention is characterized in that a plurality of surface emitting semiconductor laser elements according to the sixth or seventh embodiment are arranged.
[0134]
According to the surface-emitting type semiconductor laser device of the sixth or seventh embodiment, since the p-side can be used as a common electrode and the anode can be used as a common, a bipolar transistor drive circuit capable of high-speed operation is used. In addition, by arranging a plurality of elements in an array, more data can be transmitted simultaneously.
[0135]
Ninth embodiment
In the optical transmission module of the ninth embodiment of the present invention, the surface emitting semiconductor laser element of the sixth or seventh embodiment or the surface emitting semiconductor laser array of the eighth embodiment is used as a light source. It is characterized by being.
[0136]
The surface-emitting type semiconductor laser device of the sixth or seventh embodiment or the surface emission of the eighth embodiment has the low resistance, the low driving voltage, the low threshold current operation, and the good temperature characteristics as described above. By using the type semiconductor laser array, a low-cost optical transmission module that does not require a cooling element can be realized.
[0137]
Tenth embodiment
The optical transceiver module according to the tenth embodiment of the present invention uses the surface-emitting type semiconductor laser device according to any of the sixth or seventh embodiment or the surface-emitting type semiconductor laser array according to the eighth embodiment as a light source. It is characterized by being used.
[0138]
The surface-emitting type semiconductor laser device of the sixth or seventh embodiment or the surface emission of the eighth embodiment has the low resistance, the low driving voltage, the low threshold current operation, and the good temperature characteristics as described above. By using a type semiconductor laser array, a low-cost optical transceiver module that does not require a cooling element can be realized.
[0139]
Eleventh embodiment
The optical communication system according to the eleventh embodiment of the present invention uses the surface emitting semiconductor laser element of the sixth or seventh embodiment or the surface emitting semiconductor laser array of the eighth embodiment as a light source. It is characterized by being.
[0140]
The surface-emitting type semiconductor laser device of the sixth or seventh embodiment or the surface emission of the eighth embodiment has the low resistance, the low driving voltage, the low threshold current operation, and the good temperature characteristics as described above. By using the type semiconductor laser array, it is possible to realize an optical communication system such as a low-cost optical fiber communication system or an optical interconnection system that does not require a cooling element.
[0141]
12th embodiment
A method for manufacturing a semiconductor light emitting device according to a twelfth embodiment of the present invention is a method for manufacturing a semiconductor light emitting device in which a semiconductor layer containing Al is provided between a substrate and an active layer containing nitrogen. After the growth and before starting the growth of the active layer containing nitrogen, CBr is used as an etching gas.₄A process of supplying a gas containing bromine, such as broth, into the growth chamber (reaction chamber) and removing at least one of Al raw material, Al reactant, Al compound, and Al remaining in the growth chamber. It is a feature.
[0142]
As described above, since the Al-based residue causes oxygen that causes non-radiative recombination to be incorporated into the active layer containing nitrogen, the Al-based residue contains nitrogen after growing the semiconductor layer containing Al. Prior to the growth of the active layer, it is possible to remove the Al-based residue by reacting with the Al-based residue remaining on the reaction chamber (growth chamber) side wall, heating zone, jig holding the substrate, etc. By supplying the gas to the growth chamber, oxygen uptake into the active layer can be suppressed. CBr₄Such a gas containing bromine reacts with the reaction product deposits in the growth chamber and has the effect of etching away. Therefore, if a gas containing bromine is supplied as an etching gas after the growth of the semiconductor layer containing Al and before the growth of the active layer containing nitrogen, this etching gas will cause the reaction chamber side walls, the heating zone, and the substrate to move. Since the Al-based residue can be removed by reacting with the Al-based residue remaining in the holding jig or the like, oxygen uptake into the active layer can be suppressed.
[0143]
Moreover, the gas containing bromine has an effect of etching a semiconductor layer such as GaAs. When the growth is interrupted once and at least one of the Al raw material, Al reactant, Al compound, and Al remaining in the growth chamber is removed, an oxide film or the like may be formed on the epi-substrate surface. Therefore, after the growth is interrupted once and before re-growth, a gas containing bromine as an etching gas is supplied into the growth chamber, and a step for removing a part of the surface of the substrate to be grown is provided. Since it can be removed, adverse effects on device characteristics such as non-radiative recombination at the regrowth interface can be suppressed. That is, a method for manufacturing a semiconductor light emitting device in which a semiconductor layer containing Al is provided between a substrate and an active layer, and after growing the semiconductor layer containing Al, the active layer containing nitrogen is grown. It is preferable to provide a step of interrupting the growth once before starting and supplying a gas containing bromine as an etching gas into the growth chamber before the regrowth to remove a part of the surface of the substrate to be grown. If the element to be formed is a surface-emitting type semiconductor laser, it is important to control the thickness. Therefore, the etching depth is predicted to grow thickly in advance, or the portion to be etched during re-growth is thickened. There is a need to. As a gas containing bromine, CBr₄Besides, CH₃A gas such as Br can be used. Further, since a semiconductor layer such as GaAs can be etched using a gas containing chlorine such as HCl, a similar effect can be obtained.
[0144]
【Example】
Examples of the present invention will be described below.
[0145]
(First embodiment)
FIGS. 7A and 7B are views showing a GaInNAs surface emitting semiconductor laser device according to the first embodiment of the present invention. FIG. 7B is a partially enlarged view of FIG.
[0146]
As shown in FIGS. 7A and 7B, in the surface-emitting type semiconductor laser device of the first embodiment, each of the two-inch surface orientation (100) on the p-GaAs substrate is provided. P-Al with a thickness of 1/4 of the oscillation wavelength λ in the medium_xGa_1-xA p-semiconductor distributed Bragg reflector (lower semiconductor distributed Bragg reflector: also simply referred to as a lower reflector) having a periodic structure in which As (x = 0.9) and p-GaAs are alternately stacked for 35 periods is formed. Yes. The uppermost low-refractive index layer of the lower reflecting mirror is a low-refractive index layer having a thickness of 3λ / 4 in which AlAs serving as a selective oxidation layer is sandwiched between AlGaAs and GaInP. Here, AlAs has a thickness of 30 nm and comes to a position of 2λ / 4 from the bottom. A GaAs layer having a thickness of 40 nm is inserted between the p-AlAs selective oxidation layer and p-GaInP.
[0147]
In the surface-emitting type semiconductor laser device of the first embodiment, an undoped lower GaAs spacer layer and three layers of Ga are formed on the lower reflecting mirror._xIn_1-xN_yAs_1-y(X, y) A multiple quantum well active layer composed of a well layer and a GaAs barrier layer and an undoped upper GaAs spacer layer are formed.
[0148]
An n-semiconductor distributed Bragg reflector (upper semiconductor distributed Bragg reflector: also simply referred to as an upper reflector) is formed thereon. Here, the upper reflecting mirror is made of Si-doped n-Al._xGa_1-xIt is composed of a periodic structure (for example, 25 periods) in which As (x = 0.9) and n-GaAs are alternately stacked at a thickness of 1/4 times the oscillation wavelength in each medium. The thickness of the resonator region sandwiched between the upper reflecting mirror and the lower reflecting mirror was set to a thickness corresponding to one wavelength between the GaAs spacer layer and the multiple quantum well active layer.
[0149]
The uppermost n-GaAs layer of the upper reflecting mirror also serves as an n-GaAs contact layer that makes contact with the n-side electrode. The In composition x of the well layer in the active layer was 37%, and the nitrogen composition was 0.5%. The thickness of the well layer was 7 nm. The active layer had a compressive strain (high strain) of about 2.5% with respect to the GaAs substrate.
[0150]
Next, a mesa having a predetermined size is formed by exposing at least the side surface of the p-AlAs selective oxidation layer, and AlAs appearing on the side surface is oxidized from the side surface with water vapor to form Al._xO_yA current narrowing portion was formed. Then, the etched portion is filled with polyimide and planarized, the polyimide on the n-GaAs contact layer is removed, an n-side electrode is formed in addition to the light emitting portion on the n-GaAs contact layer, and the substrate A p-side electrode was formed on the back surface.
[0151]
Such a surface emitting semiconductor laser element can be formed by MOCVD. In this case, the raw material for the GaInNAs active layer by MOCVD is TMG (trimethylgallium), TMI (trimethylindium), AsH.₃(Arsine) can be used, and DMHy (dimethylhydrazine) can be used as a raw material of nitrogen. The carrier gas is H₂Can be used. Here, since DMHy decomposes at a low temperature, it is suitable for a low temperature growth of 600 ° C. or less, and is a preferable raw material particularly when a quantum well layer having a large strain required for low temperature growth is grown. Further, when the strain is large as in the active layer of the GaInNAs surface-emitting type semiconductor laser device of the first embodiment, low temperature growth that is non-equilibrium is preferable. In this first example, the GaInNAs layer was grown at 540 ° C.
[0152]
By the way, in the first embodiment, a GaAs layer (with a thickness of 40 nm) provided in the uppermost low-refractive index layer of the lower reflector is used to suppress the oxygen incorporation into the active layer and prevent the light emission efficiency from being lowered. The growth substrate is suspended in the middle of the growth, and the substrate to be grown is once moved to another chamber, the susceptor holding the substrate to be grown is returned to the growth chamber, and the carrier gas H₂While supplying the gas, the susceptor was heated at a temperature higher than the growth temperature to exclude Al-based residues. At this time, the temperature of the growth chamber walls other than the susceptor also rises, and the removal of Al-based residues is accelerated. Thereby, oxygen uptake into the active layer could be suppressed. This step may be performed after the growth of the semiconductor layer containing Al and before the growth of the active layer containing nitrogen. Preferably, as in the first embodiment, a material having a band gap larger than the band gap of the growth interrupted interface (in this first embodiment, a GaAs layer) and containing no Al (this first embodiment). In the embodiment, GaInP) is preferably formed between the active layer containing nitrogen.
[0153]
That is, the surface of the substrate to be grown is oxidized or otherwise removed by interrupting the crystal growth and removing the Al-based residue remaining on the reaction chamber side wall, heating zone, jig holding the substrate, and the like. The damage may occur due to damage. If this place (region) is an active region into which carriers are injected, the generated defect becomes a non-radiative recombination center, and the light emission efficiency is lowered when the light emitting element is operated.
[0154]
On the other hand, as in the first embodiment, a GaInPAs layer, a GaInP layer, or a GaPAs layer having a band gap energy higher than the band gap energy of the surface material at the time of removing Al-based residues is changed to nitrogen. When the device is grown between the active layer and the active layer, almost no carriers injected into the surface when the Al-based residue is removed during device operation. It becomes possible.
[0155]
In the first embodiment, the Al-based residue removing step is performed by interrupting crystal growth when crystal growth is performed using one crystal growth apparatus. Even when an apparatus for growing an active layer containing nitrogen is separately used for crystal growth, the Al-based residue removal step can be performed by interrupting the crystal growth. That is, when an active layer containing nitrogen is grown, the Al-based residue in the device may be prevented from being taken into the active layer together with oxygen.
[0156]
The oscillation wavelength of the surface emitting semiconductor laser device fabricated as described above was about 1.3 μm. In this first embodiment, since GaInNAs was used for the active layer, a long-wavelength surface emitting semiconductor laser element could be formed on the GaAs substrate. Further, in this first embodiment, the compound containing residual Al is excluded so that the compound containing Al remaining in the apparatus is not taken into the film together with oxygen during the growth of the active layer containing nitrogen. Therefore, it was possible to prevent oxygen from being mixed with Al in the active layer. As a result, a GaInNAs surface-emitting type semiconductor laser device that has high emission efficiency and oscillates at a low threshold value can be manufactured by the MOCVD method advantageous for mass production.
[0157]
Further, since the current narrowing layer was formed by selective oxidation of the selective oxidation layer containing Al and As as main components, the threshold current was low. According to the current narrowing structure using the current narrowing layer made of the Al oxide film that selectively oxidizes the selective oxidation layer, the current narrowing layer is formed close to the active layer, so that the current spread can be suppressed and the atmosphere is not touched. Carriers can be confined efficiently in a minute region. Furthermore, by oxidizing to become an Al oxide film, the refractive index is reduced, and the light can be efficiently confined in a minute region where carriers are confined by the effect of the convex lens, and the threshold current is improved. Can be reduced. In addition, since the current narrowing structure can be easily formed, the manufacturing cost can be reduced.
[0158]
The MBE method was mainly used as a method for growing a semiconductor layer such as GaInNAs containing nitrogen and other group V. However, since the MBE method is principally grown in a high vacuum, the amount of raw material supply Cannot be increased. When the amount of raw material supply is increased, there is a disadvantage that a burden is imposed on the exhaust system. The MBE method requires an exhaust pump of a high vacuum exhaust system, but the throughput is poor because the exhaust system is burdened and easily broken to remove residual raw materials in the MBE chamber.
[0159]
The surface-emitting type semiconductor laser element is configured by sandwiching an active region including at least one active layer that generates laser light between semiconductor multilayer reflectors. While the thickness of the crystal growth layer of the edge-emitting laser is about 3 μm, for example, a surface-emitting semiconductor laser element having a wavelength band of 1.3 μm requires a thickness exceeding 10 μm. Since a vacuum is required, the raw material supply rate cannot be increased, the growth rate is about 1 μm / h, and a growth interruption time for changing the raw material supply amount is required to grow a thickness of 10 μm. If not, it will take at least 10 hours.
[0160]
Here, the thickness of the active region is usually very small compared to the whole (10% or less), and most of them are layers constituting the multilayer reflector. The semiconductor multilayer mirror is formed by alternately laminating a low refractive index layer and a high refractive index layer with a thickness (1/4) of the oscillation wavelength in each medium (λ / 4 thickness) (for example, 20 to 20). 40 pairs) are formed. In the surface emitting semiconductor laser device on the GaAs substrate, the semiconductor multilayer reflector is made of an AlGaAs-based material to change the Al composition into a low refractive index layer (Al composition large) and a high refractive index layer (Al composition small). . In practice, however, the resistance is increased particularly on the p side due to the hetero-barrier of each layer. Therefore, an interlayer having an Al composition between the low refractive index layer and the high refractive index layer is inserted to reflect the multilayer film. The resistance of the mirror is reduced.
[0161]
As described above, the surface-emitting type semiconductor laser device has to grow semiconductor layers having different compositions exceeding 100 layers, and also between the low refractive index layer and the high refractive index layer of the multilayer reflector. It is an element that needs to control the amount of material supply instantaneously, such as providing an intermediate layer. However, in the MBE method, the supply amount is controlled by changing the temperature of the raw material cell, and the composition cannot be controlled flexibly. Therefore, it is difficult to reduce the resistance of the semiconductor multilayer mirror grown by the MBE method, and the operating voltage is increased.
[0162]
On the other hand, the MOCVD method only needs to control the raw material gas flow rate, can control the composition instantaneously, does not require a high vacuum like the MBE method, and can easily increase the growth rate to 3 μm / h or more, for example. Therefore, the growth method is extremely suitable for mass production.
[0163]
As described above, according to the first embodiment, a 1.3 μm-band surface emitting semiconductor laser device with low power consumption and low cost can be realized by using the MOCVD method.
[0164]
(Second embodiment)
FIGS. 8A and 8B are views showing a GaInNAs surface emitting semiconductor laser element according to the second embodiment of the present invention. FIG. 8B is a partially enlarged view of FIG. This second embodiment is different from the first embodiment in that the step of removing at least one of Al raw material, Al reactant, Al compound, and Al remaining in the growth chamber is performed in the multilayer reflector. Rather, it is performed inside the resonator. As a result, the mixing of oxygen into the active layer containing nitrogen was suppressed, and the luminous efficiency could be improved.
[0165]
However, in this second embodiment, the step of removing at least one of the Al raw material, Al reactant, Al compound, and Al remaining in the growth chamber is not performed in the multilayer reflector but in the resonator. Doing so may cause defects on the surface of the substrate to be grown due to oxidation or other damage. If this location (region) is an active region into which carriers are injected, the generated defect is non-existent. Since it becomes a light emission recombination center and the light emission efficiency may decrease during operation of the light emitting device, the band gap of the surface material (GaAs in this second embodiment, which is the growth interruption interface) when removing the Al-based residue. A GaPAs layer having a higher band gap energy than the energy is provided between the active layer containing nitrogen. The active layer of the second embodiment has a large compressive strain exceeding 2%, and GaPAs has a tensile strain with respect to the GaAs substrate. Therefore, GaPAs reduces the adverse effect of the strain. There is also an effect. For this reason, in the second embodiment, a GaPAs layer is also provided on the active layer.
[0166]
In the above-described example, the GaPAs layer is provided, but a GaInPAs layer or a GaInP layer may be provided instead of the GaPAs layer.
[0167]
As a result, almost no carriers are injected into the surface when the Al-based residue is removed during device operation, so that the light emission efficiency is not lowered, and the GaInNAs surface emitting semiconductor laser oscillates at a low threshold with high light emission efficiency. The device could be manufactured by the MOCVD method which is advantageous for mass production.
[0168]
(Third embodiment)
FIG. 9 is a diagram showing a GaInNAs surface emitting semiconductor laser element according to the third embodiment of the present invention.
[0169]
This third embodiment differs from the second embodiment in that the step of removing at least one of the Al raw material, Al reactant, Al compound, and Al remaining in the growth chamber is performed on the GaAs lower spacer layer. During the growth, DMHy is supplied to grow a GaNAs layer. This GaNAs layer has a condition that the band gap energy is larger than that of the GaInNAs active layer.
[0170]
The oscillation wavelength of the surface-emitting type semiconductor laser device manufactured according to the third example was about 1.3 μm. In the third embodiment, since GaInNAs is used for the active layer, a long-wavelength surface emitting semiconductor laser element can be formed on the GaAs substrate.
[0171]
Further, in the third embodiment, DMHy as an etching gas is supplied so that the compound containing Al remaining in the apparatus is not taken into the active layer together with oxygen during the growth of the active layer containing nitrogen. Since the GaNAs layer is grown, Al was taken into the removed GaNAs layer along with oxygen, but the compound containing Al remaining in the reaction chamber was excluded before the growth of the active layer, It can suppress that oxygen mixes with Al. That is, the GaNAs layer subjected to this removal step can be said to be a dummy layer of the active layer. As a result, in the third embodiment, a GaInNAs surface-emitting type semiconductor laser device that has high emission efficiency and oscillates at a low threshold value can be manufactured by the MOCVD method advantageous for mass production.
[0172]
(Fourth embodiment)
FIG. 10 is a diagram showing a GaInNAs surface emitting semiconductor laser array (GaInNAs surface emitting semiconductor laser array chip) according to a fourth embodiment of the present invention.
[0173]
The GaInNAs surface-emitting type semiconductor laser array of the fourth embodiment has 10 surface-emitting semiconductor laser elements of the first embodiment arranged in one dimension. The GaInNAs surface emitting semiconductor laser array of the fourth embodiment may be a two-dimensionally integrated surface emitting semiconductor laser element of the first embodiment. The GaInNAs surface emitting semiconductor laser array of the fourth embodiment is formed on a p-type GaAs semiconductor substrate, an n-side individual electrode is formed on the top surface, and a p-side common electrode is formed on the back surface of the substrate. Has been.
[0174]
In the fourth embodiment, a long-wavelength surface emitting semiconductor laser array using a selective oxidation structure that is configured to be a p-side common electrode and is suitable for high performance is manufactured by MOCVD with excellent mass productivity. It became possible to make by the method.
[0175]
In the fourth embodiment, a p-type substrate is used. However, crystal growth can also be performed on a semi-insulating substrate in the order of the p-side, the active layer, and the n-side. In this case as well, The structure of the p-side common electrode can be formed. In this case, the common electrode is formed not on the back surface but on the same side as the n side.
[0176]
(Fifth embodiment)
FIG. 11 is a diagram showing an optical transmission module according to a fifth embodiment of the present invention. The optical transmission module according to the fifth embodiment includes the surface-emitting type semiconductor laser array chip of the fourth embodiment and an optical fiber. It is a combination. In the optical transmission module of the fifth embodiment, laser transmission from a 1.3 μm band GaInNAs surface emitting semiconductor laser element can be input to a silica-based optical fiber for optical transmission. Here, the wavelength was 1.3 μm suitable for optical fiber communication, and a single mode fiber could be used.
[0177]
In the fifth embodiment, the GaInNAs surface emitting semiconductor laser array of the fourth embodiment is used, and the p-side is shared, so that a bipolar transistor drive circuit capable of high-speed operation can be employed. As a result, high-speed parallel transmission is possible, and more data than before can be transmitted simultaneously.
[0178]
In this fifth embodiment, the surface emitting semiconductor laser elements and the optical fibers are made to correspond one-to-one. However, a plurality of surface emitting semiconductor laser elements having different oscillation wavelengths are arrayed in one or two dimensions. It is possible to further increase the transmission rate by arranging in the wavelength division multiplexing and wavelength multiplexing transmission.
[0179]
Furthermore, when the surface emitting semiconductor laser device according to the present invention is used in an optical communication system, a low-cost and highly reliable optical transmission module can be realized, and a low-cost and high-reliability optical communication system using the same can be realized. . In addition, since the surface emitting semiconductor laser element using GaInNAs has good temperature characteristics and a low threshold value, a system that generates little heat and can be used without cooling to a high temperature can be realized.
[0180]
(Sixth embodiment)
FIG. 12 is a diagram showing an optical transceiver module according to the sixth embodiment of the present invention. The optical transceiver module according to the sixth embodiment includes a surface emitting semiconductor laser element and a receiving photodiode according to the fifth embodiment. And optical fiber.
[0181]
When the surface-emitting type semiconductor laser device according to the present invention is used in an optical communication system, the surface-emitting type semiconductor laser device is low-cost, so that a surface-emitting type semiconductor laser device for transmission (1.3 μm band) is used as shown in FIG. A low-cost, high-reliability optical communication system using an optical transmission module in which a GaInNAs surface emitting semiconductor laser device), a receiving photodiode, and an optical fiber are combined can be realized. Further, in the case of the surface emitting semiconductor laser device using GaInNAs according to the present invention, the temperature characteristics are good, the operating voltage is low, and the threshold value is low, so there is little heat generation and no cooling to high temperature. A lower cost system can be realized.
[0182]
Furthermore, when a fluorine-doped POF (plastic fiber) that has a low loss in a long wavelength band such as 1.3 μm and a surface emitting laser using GaInNAs as an active layer are combined, the cost of the fiber is reduced. Since it is large, coupling with a fiber is easy and the mounting cost can be reduced, an extremely low cost module can be realized.
[0183]
As an optical communication system using the surface emitting semiconductor laser device according to the present invention, not only can it be used for long-distance communication using an optical fiber, but also transmission between devices such as a computer such as a LAN (Local Area Network), Furthermore, it can be used for short-distance communication as optical interconnection such as data transmission between boards, LSI between boards, and elements between LSIs.
[0184]
In recent years, the processing performance of LSIs and the like has improved, but the transmission speed of the portion connecting them will become a bottleneck in the future. When the signal connection in the system is changed from the conventional electrical connection to the optical interconnect (for example, between the boards of the computer system, between the LSIs in the board, between the elements in the LSI, etc., the optical transmission module or optical transmission / reception module according to the present invention is used. Connection), an ultra-high speed computer system becomes possible.
[0185]
Further, when a plurality of computer systems or the like are connected using the optical transmission module or the optical transmission / reception module according to the present invention, an ultra-high speed network system can be constructed. In particular, the surface emitting semiconductor laser element is suitable for a parallel transmission type optical communication system because it can reduce power consumption by an order of magnitude compared to the edge emitting laser and can easily form a two-dimensional array.
[0186]
As described above, according to the GaInNAs-based material which is a semiconductor layer (active layer) containing nitrogen, Al (Ga) As / which has a proven record in a 0.85 μm band-emitting semiconductor laser device using a GaAs substrate. (Al) GaAs-based semiconductor multilayer distributed Bragg reflector and current narrowing structure by selective oxidation of AlAs can be applied, and by manufacturing a surface emitting semiconductor laser device by the manufacturing method according to the present invention, the crystal quality of the GaInNAs active layer , Lower resistance of multilayer reflectors, and improved crystal quality and controllability of multilayer film structures as surface emitting semiconductor laser elements. A wavelength-band surface-emitting semiconductor laser device can be realized. Furthermore, when these devices are used, a cooling element is not required and a low-cost optical fiber communication system, optical interface An optical communication system such as a connection system can be realized.
[0187]
(Seventh embodiment)
The configuration of the GaInNAs surface emitting semiconductor laser device of the seventh embodiment is the same as that of FIG. 8 described in the second embodiment. The seventh embodiment differs from the second embodiment in the following points. That is, in the seventh embodiment, the step of removing at least one of Al raw material, Al reactant, Al compound, and Al remaining in the growth chamber is interrupted during the growth of the GaAs lower spacer layer, and once The substrate to be grown is moved to another chamber, the susceptor holding the substrate to be grown is returned to the growth chamber, the susceptor is heated at a temperature higher than the growth temperature, and the carrier gas H₂CBr with gas₄Is done by supplying the growth chamber.
[0188]
In the seventh embodiment, CBr, which is an etching gas, is used so that the Al-based residue remaining in the apparatus is not taken into the active layer together with oxygen during the growth of the active layer containing nitrogen.₄Therefore, the Al-based residue remaining in the reaction chamber is removed before the growth of the active layer, and oxygen can be prevented from being mixed with the Al in the active layer. Thus, in the seventh embodiment, a GaInNAs surface-emitting type semiconductor laser device that has high emission efficiency and oscillates at a low threshold value can be manufactured by the MOCVD method advantageous for mass production. CBr₄In addition to CH₃A gas such as Br can be used.
[0189]
Further, when the substrate side is a p-type semiconductor as in the present invention, the following effects can be obtained. That is, Japanese Patent Application Laid-Open No. 11-274083 shows that mixing of hydrogen (H) into a GaInNAs-based active layer causes problems such as deterioration of light emission characteristics. In general, a phenomenon in which an acceptor is inactivated by atomic hydrogen is known for GaAs, InP, AlGaInP, and the like. This can be activated by annealing. AsH during temperature drop after growth₃Hydrogen diffuses from the p layer (for example, p-GaAs) on the outermost surface as atomic hydrogen. The theory that atomic hydrogen loses electrons due to the presence of holes in a p-type semiconductor to become protons and accelerates the diffusion rate has been studied. It is known that this can be prevented by making the surface an n layer (for example, n-GaAs). Especially when a GaInNAs material is formed by MOCVD, H₂, AsH₃As a raw material and atmospheric gas, N (such as DMHy) contains carbon (C) in the raw material, and low temperature growth is preferable. And hydrogen is easily mixed. When the substrate side is a p-type semiconductor as in the present embodiment, an n-type semiconductor can be formed on the surface, and the effect of suppressing the entry of hydrogen from the surface can also be obtained.
[0190]
Further, by adding an n-type dopant (eg, Si, Ge, Se, S, Te) to the GaInNAs-based active layer to form an n-type semiconductor, atomic hydrogen enters even during the growth of the GaInNAs-based active layer. Can be prevented.
[0191]
(Eighth embodiment)
The configuration of the GaInNAs surface emitting semiconductor laser element of the eighth embodiment is the same as that of FIG. 8 described in the second and seventh embodiments. The eighth embodiment is different from the second embodiment in that the growth of the GaAs lower spacer layer is interrupted during the growth, the substrate to be grown is once moved to another chamber, and the Al source, Al reactant, After performing the step of removing at least one of the Al compound and Al, the substrate to be grown is returned to the growth chamber, the temperature of the susceptor is heated to a predetermined etching temperature, and the carrier gas H₂CBr with gas₄Is supplied to the growth chamber, the surface of the substrate to be grown is removed by etching, and then the remaining crystal growth (re-growth) is performed.
[0192]
When the removal of the Al-based residue is performed with the growth interrupted, the surface of the substrate to be grown may be oxidized and other damages to cause defects. In this embodiment, a GaPAs layer having a band gap larger than that of a semiconductor layer (in this embodiment, a GaAs spacer layer) that forms a regrowth interface between the regrowth interface and an active layer containing nitrogen is provided. Since the surface of the substrate to be grown is removed by etching before growth (by supplying a gas containing bromine that has an effect of etching a compound semiconductor such as GaAs, a part of the GaAs spacer layer on the surface of the substrate to be grown is removed. Since it was removed by etching, adverse effects on device characteristics such as non-radiative recombination at the regrowth interface could be more reliably suppressed. In addition, since control of the thickness is important in the surface emitting laser, the etching depth is estimated and the portion to be etched is grown thick. In addition to this, it is also possible to grow by thickening the portion to be etched during regrowth. As a gas containing bromine, CBr₄Besides, CH₃A gas such as Br can be used.
[0193]
As a result, in the eighth embodiment, a GaInNAs surface emitting semiconductor laser element that has high emission efficiency and oscillates at a low threshold value can be manufactured by the MOCVD method advantageous for mass production.
[0194]
【The invention's effect】
  As described above, according to the first to seventh aspects of the present invention, the p-type semiconductor layer has the p-type semiconductor layer between the active layer containing nitrogen and the semiconductor substrate.Contains Al and AsA method for manufacturing a semiconductor light emitting device, comprising a selective oxidation layer and selectively oxidizing a portion of the arranged selective oxidation layer to form a current confinement structure, wherein after the growth of the selective oxidation layer, nitrogen is formed Al source material, Al reactant, Al compound, Al remaining in the gas supply line or in the growth chamber where the nitrogen compound raw material or impurities contained in the nitrogen compound raw material come into contact before the start of growth of the active layer containing Since a step of removing at least one of them is provided, oxygen uptake into the active layer can be suppressed, and a semiconductor light-emitting element with high emission efficiency can be manufactured.
[0195]
In particular, according to a second aspect of the present invention, in the method for manufacturing a semiconductor light emitting device according to the first aspect, the nitrogen compound raw material or the nitrogen compound is formed after the growth of the selective oxidation layer and before the start of the growth of the active layer containing nitrogen. The step of removing at least one of the Al raw material, Al reactant, Al compound, and Al remaining in the gas supply line or the growth chamber where the impurities contained in the raw material come into contact is interrupted by the growth, and the carrier Since the gas supply line or the growth chamber is purged with gas, the Al residue remaining on the reaction chamber side wall, heating zone, jig for holding the substrate, etc. is removed, and oxygen is taken into the active layer. Thus, a semiconductor light emitting element with high luminous efficiency can be manufactured.
[0196]
According to a third aspect of the invention, in the method for manufacturing a semiconductor light emitting device according to the second aspect, since the susceptor is baked during the growth interruption, it is possible to efficiently suppress oxygen uptake into the active layer. Thus, a semiconductor light emitting device with high luminous efficiency can be manufactured.
[0197]
According to a fourth aspect of the present invention, in the method for manufacturing a semiconductor light-emitting device according to the first aspect, the nitrogen compound raw material or the material after the growth of the selective oxidation layer and before the growth of the active layer containing nitrogen is started. The process of removing at least one of the Al raw material, Al reactant, Al compound, and Al remaining in the gas supply line or in the growth chamber where the impurities contained in the nitrogen compound raw material come into contact is grown with an etching gas. Since it is a process of supplying to the chamber, oxygen uptake into the active layer can be suppressed, and a semiconductor light emitting element with high luminous efficiency can be obtained.
[0198]
According to a fifth aspect of the present invention, in the method of manufacturing a semiconductor light emitting device according to the fourth aspect, the etching gas is an organic nitrogen compound gas, and the organic nitrogen compound gas is added to the side wall of the reaction chamber. In the tropics, it can react with the Al-based residue remaining on the jig holding the substrate and remove the Al-based residue, so that the oxygen uptake into the active layer can be suppressed, and the luminous efficiency is high. A semiconductor light emitting device can be obtained.
[0199]
According to a sixth aspect of the present invention, in the method for manufacturing a semiconductor light emitting device according to the fourth aspect, the etching gas is a gas containing oxygen (O), and the gas containing oxygen (O) is reacted. It can react with the Al-based residue remaining in the chamber side wall, heating zone, jig holding the substrate, etc., and can remove the Al-based residue, so that the oxygen uptake into the active layer can be suppressed, A semiconductor light emitting device with high luminous efficiency can be obtained.
[0200]
According to a seventh aspect of the present invention, in the method for manufacturing a semiconductor light emitting device according to the fourth aspect, the etching gas is a gas containing chlorine (Cl), and the gas containing chlorine (Cl) is a reaction Since it can react with the Al-based residue remaining on the chamber side wall, heating zone, jig holding the substrate, etc., the Al-based residue can be removed, so that the incorporation of oxygen into the active layer can be suppressed, A semiconductor light emitting device with high luminous efficiency can be obtained.
[0201]
  In addition, according to the invention described in claims 8 to 14, the p-type semiconductor layer is provided between the active layer containing nitrogen and the semiconductor substrate, and the p-type semiconductor layer includes the p-type semiconductor layer.Contains Al and AsA selective oxidation layer is disposed, a part of the disposed selective oxidation layer is selectively oxidized to form a current confinement structure, and at least between the selective oxidation layer and the active layer containing nitrogen. A method for manufacturing a semiconductor light emitting device for forming a single GaInPAs layer, a GaInP layer, or a GaPAs layer, wherein the growth of the selective oxidation layer is followed by the growth of the GaInPAs layer, the GaInP layer, or the GaPAs layer. In the gas supply line where the nitrogen compound raw material or impurities contained in the nitrogen compound raw material come into contact or in the growth chamber, at least of the Al raw material, Al reactant, Al compound, and Al remaining in the growth chamber A step of removing one is provided, and growth is interrupted outside the active region where carriers are not injected to remove the Al-based residue, whereby residual A Luminous efficiency by non-radiative recombination due to non-radiative recombination and Al-based residue removal caused can be suppressed to decrease the.
[0202]
Particularly, in the invention according to claim 9, in the method for manufacturing a semiconductor light emitting element according to claim 8, in the method for manufacturing a semiconductor light emitting element according to claim 8, the GaInPAs layer or Al raw material and Al reactant remaining in the gas supply line or in the growth chamber where the nitrogen compound raw material or impurities contained in the nitrogen compound raw material come into contact until the growth of the GaInP layer or GaPAs layer is completed The step of removing at least one of Al, Al compound and Al is a step of interrupting the growth and purging the gas supply line or the growth chamber with the carrier gas, so that the reaction chamber side wall, the heating zone, and the substrate are held. Al-based residues remaining on jigs and the like can be removed, and oxygen uptake into the active layer can be suppressed, producing a semiconductor light emitting device with high luminous efficiency. It can be.
[0203]
Further, in the invention according to claim 10, in the method of manufacturing a semiconductor light emitting device according to claim 8, since the susceptor is baked during the growth interruption, it is possible to efficiently suppress oxygen uptake into the active layer. Thus, a semiconductor light emitting device with high luminous efficiency can be manufactured.
[0204]
According to the invention of claim 11, in the method of manufacturing a semiconductor light emitting device according to claim 8, the nitrogen compound raw material or the material after the growth of the selective oxidation layer and before the growth of the active layer containing nitrogen is started. The process of removing at least one of the Al raw material, Al reactant, Al compound, and Al remaining in the gas supply line or in the growth chamber where the impurities contained in the nitrogen compound raw material come into contact is grown with an etching gas. Since it is a process of supplying to the chamber, oxygen uptake into the active layer can be suppressed, and a semiconductor light emitting element with high luminous efficiency can be obtained.
[0205]
According to a twelfth aspect of the present invention, in the method for manufacturing a semiconductor light emitting device according to the eighth aspect, the etching gas is an organic nitrogen compound gas, and the organic nitrogen compound gas is added to the side wall of the reaction chamber. In the tropics, it can react with the Al-based residue remaining on the jig holding the substrate and remove the Al-based residue, so that the oxygen uptake into the active layer can be suppressed, and the luminous efficiency is high. A semiconductor light emitting device can be obtained.
[0206]
According to a thirteenth aspect of the present invention, in the method for manufacturing a semiconductor light emitting device according to the eighth aspect, the etching gas is a gas containing oxygen (O), and the gas containing oxygen (O) is reacted. It can react with the Al-based residue remaining in the chamber side wall, heating zone, jig holding the substrate, etc., and can remove the Al-based residue, so that the oxygen uptake into the active layer can be suppressed, A semiconductor light emitting device with high luminous efficiency can be obtained.
[0207]
According to a fourteenth aspect of the present invention, in the method for manufacturing a semiconductor light emitting device according to the eighth aspect, the etching gas is a gas containing chlorine (Cl), and the gas containing chlorine (Cl) is a reaction Since it can react with the Al-based residue remaining on the chamber side wall, heating zone, jig holding the substrate, etc., the Al-based residue can be removed, so that the incorporation of oxygen into the active layer can be suppressed, A semiconductor light emitting device with high luminous efficiency can be obtained.
[0211]
  Also,Claims 15 to 17According to the described invention, the p-type semiconductor layer is provided between the active layer containing nitrogen and the semiconductor substrate, and is disposed in the p-type semiconductor layer.Contains Al and AsIn the semiconductor light emitting device in which a part of the selective oxidation layer is selectively oxidized to form a current confinement structure, a band gap is larger between the selective oxidation layer and the active layer containing nitrogen than the active layer. Since a large semiconductor layer containing nitrogen is formed, at least one of Al raw material, Al reactant, Al compound, and Al remaining in the growth chamber is removed during growth, and oxygen is taken into the active layer. And the luminous efficiency can be increased. In the case of a semiconductor laser, the threshold current can be made sufficiently low.
[0212]
  In particular,Claim 16According to the described invention,Claim 15In the semiconductor light-emitting element described above, the semiconductor layer having a band gap larger than that of the active layer and containing nitrogen is any one of GaNAs, GaInNAs, GaInNP, GaNPAs, and GaInNPAs, so that the light emission efficiency can be increased. In the case of a semiconductor laser, the threshold current can be made sufficiently low.
[0213]
  Also,Claim 17According to the described invention,Claim 15In the described semiconductor light emitting device, GaAs, GaInAs, GaAsP, GaInPAs, GaInP having a band gap larger than that of the active layer and having a band gap energy higher than that between the semiconductor layer containing nitrogen and the active layer containing nitrogen. Since the layer composed of any one of the above is formed, the band gap is larger than that of the active layer and almost no carriers are injected into the semiconductor layer containing nitrogen, so that the light emission efficiency can be increased. In the case of a semiconductor laser, the threshold current can be made sufficiently low.
[0214]
  Also,Claims 18 to 20According to the described invention, it comprises a resonator structure including an active region having an active layer containing nitrogen, and upper and lower reflecting mirrors provided above and below the active layer to obtain laser light, A method of manufacturing a surface-emitting type semiconductor laser device having a p-type semiconductor layer between an active layer containing nitrogen and a semiconductor substrate, wherein the lower reflecting mirror has a refractive index that periodically changes and incident light Including a semiconductor distributed Bragg reflector that reflects light by light wave interference, and the layer having a small refractive index of the semiconductor distributed Bragg reflector is Al._xGa_{1- x}The layer composed of As (0 <x ≦ 1) and having a large refractive index of the semiconductor distributed Bragg reflector is made of Al._yGa_{1- y}As (0 ≦ y <x ≦ 1) for selectively oxidizing a part of the p-type semiconductor layer for current confinementContains Al and AsA selective oxidation layer is formed, and at least one GaInPAs layer, GaInP layer, or GaPAs layer is formed between the selective oxidation layer and an active layer containing nitrogen, and the growth of the selective oxidation layer is performed After that, until the growth of the GaInPAs layer, the GaInP layer, or the GaPAs layer is completed, the nitrogen compound raw material or the impurity contained in the nitrogen compound raw material is in the gas supply line or in the growth chamber where the impurities come into contact. Since a step of removing at least one of the remaining Al raw material, Al reactant, Al compound, and Al is provided, the incorporation of oxygen into the active layer containing nitrogen is suppressed and the growth is interrupted. Surface emission with good temperature characteristics, avoiding the effects of non-radiative recombination due to defects, low resistance, low driving voltage, high luminous efficiency, low threshold current operation The semiconductor laser element can be manufactured easily at low cost.
[0215]
  In particular,Claim 19According to the described invention,Claim 18In the manufacturing method of the surface-emitting type semiconductor laser device described above, a place where the nitrogen compound raw material or impurities contained in the nitrogen compound raw material are in contact between the growth of the selective oxidation layer and the start of the growth of the active layer containing nitrogen The process of removing at least one of the Al raw material, Al reactant, Al compound, and Al remaining in the gas supply line or in the growth chamber is interrupted and the gas supply line or growth chamber is purged with the carrier gas. Therefore, the incorporation of oxygen into the active layer containing nitrogen can be efficiently suppressed, the driving voltage is low, the driving voltage is low, the luminous efficiency is high, the low threshold current operation is performed, and the temperature characteristics are A good surface emitting semiconductor laser device can be easily realized at low cost.
[0216]
  Also,Claim 20In the described invention, since the susceptor is baked during the growth interruption, the incorporation of oxygen into the active layer containing nitrogen can be efficiently suppressed, the driving voltage is low, the driving voltage is low, and the luminous efficiency is high and low. A surface emitting semiconductor laser element that operates with a threshold current and has good temperature characteristics can be easily realized at low cost.
[0218]
  Also,Claims 21 to 23According to the described invention, it comprises a resonator structure including an active region having an active layer containing nitrogen, and upper and lower reflecting mirrors provided above and below the active layer to obtain laser light, A surface-emitting semiconductor laser device having a p-type semiconductor layer between an active layer containing nitrogen and a semiconductor substrate, wherein the lower reflecting mirror periodically changes the refractive index and causes incident light to interfere with light waves. Including a semiconductor distributed Bragg reflector that has a low refractive index of the semiconductor distributed Bragg reflector._xGa_{1- x}The layer composed of As (0 <x ≦ 1) and having a large refractive index of the semiconductor distributed Bragg reflector is made of Al._yGa_{1- y}As (0 ≦ y <x ≦ 1) for selectively oxidizing a part of the p-type semiconductor layer for current confinementContains Al and AsA semiconductor layer having a selective oxidation layer and having a band gap larger than the active layer and containing nitrogen is formed between the selective oxidation layer and the active layer containing nitrogen. Oxygen uptake is suppressed, surface-emitting semiconductor laser devices with low resistance, low driving voltage, high luminous efficiency, low threshold current operation, and good temperature characteristics can be easily realized at low cost. . Furthermore, according to this configuration, a p-type substrate can be used.
[0219]
  In particular,Claim 22According to the described invention,Claim 21In the surface-emitting type semiconductor laser device described above, the semiconductor layer having a band gap larger than that of the active layer and containing nitrogen is any one of GaNAs, GaInNAs, GaInNP, GaNPAs, and GaInNPAs. Therefore, it is possible to easily realize a surface emitting semiconductor laser device having a low resistance, a low driving voltage, a high light emission efficiency, a low threshold current operation, and good temperature characteristics at low cost.
[0220]
  Also,Claim 23According to the described invention,Claim 21In the surface-emitting type semiconductor laser device described above, GaAs, GaInAs, GaAsP, which has a band gap larger than that of the active layer and between the semiconductor layer containing nitrogen and the active layer containing nitrogen, which has a band gap energy larger than both. Since a layer made of any one of GaInPAs and GaInP is formed, the band gap is larger than that of the active layer, almost no carriers are injected into the semiconductor layer containing nitrogen, the driving voltage is low, the driving voltage is low, and the luminous efficiency Therefore, it is possible to easily realize a surface-emitting type semiconductor laser device having a high temperature characteristic, a low threshold current operation, and good temperature characteristics.
[0221]
  Also,Claim 24According to the described invention,Claims 21 to 23Since the surface emitting semiconductor laser array is configured by arranging a plurality of the surface emitting semiconductor laser elements according to any one of the above, more data can be transmitted simultaneously by the plurality of elements.
[0222]
  Also,Claim 25According to the described invention,Claims 21 to 23Or a surface emitting semiconductor laser element according to any one ofClaim 24The surface-emitting semiconductor laser array described above is an optical transmission module that is used as a light source, and has the above-described low resistance, low driving voltage, low threshold current operation, and good temperature characteristics. By using a type semiconductor laser element or a surface emitting semiconductor laser array, a low-cost optical transmission module that does not require a cooling element can be realized.
[0223]
  Also,Claim 26According to the described invention,Claims 21 to 23Or a surface emitting semiconductor laser element according to any one ofClaim 24The surface emitting semiconductor laser array described above is used as a light source, and is a surface emitting device according to the present invention having a low resistance, a low driving voltage, a low threshold current operation, and good temperature characteristics as described above. By using a type semiconductor laser element or a surface emitting semiconductor laser array, a low-cost optical transmission / reception module that does not require a cooling element can be realized.
[0224]
  Also,Claim 27According to the described invention,Claims 21 to 23Or a surface emitting semiconductor laser element according to any one ofClaim 24The surface emitting semiconductor laser array according to the present invention is an optical communication system in which the described surface emitting semiconductor laser array is used as a light source, and has a low resistance, a low driving voltage, a low threshold current operation, and good temperature characteristics as described above. By using a semiconductor laser element or a surface emitting semiconductor laser array, it is possible to realize an optical communication system such as a low-cost optical fiber communication system or an optical interconnection system that does not require a cooling element.
[0225]
  Also,Claim 28According to the described invention, there is provided a method for manufacturing a semiconductor light emitting device in which a semiconductor layer containing Al is provided between a substrate and an active layer, wherein the semiconductor light emitting device is grown after the semiconductor layer containing Al is grown. Before starting the growth of the active layer, a gas containing bromine as an etching gas is supplied into the growth chamber to remove at least one of the Al raw material, Al reactant, Al compound, and Al remaining in the growth chamber. Since the process is provided, a semiconductor light emitting element with high luminous efficiency can be obtained. That is, CBr₄Such a gas containing bromine reacts with the reaction product deposits in the growth chamber and has the effect of etching away. Therefore, when a gas containing bromine is supplied as an etching gas after the growth of the semiconductor layer containing Al and before the growth of the active layer containing nitrogen, it reacts with the Al-based residue in the apparatus and reacts with the Al-based. Since the residue can be removed, oxygen uptake into the active layer can be suppressed, and a semiconductor light-emitting element with high emission efficiency can be obtained.
[0226]
  Also,Claim 29According to the described invention, there is provided a method for manufacturing a semiconductor light emitting device in which a semiconductor layer containing Al is provided between a substrate and an active layer, and after the semiconductor layer containing Al is grown, nitrogen is contained. Before starting the growth of the active layer, the growth was interrupted once, and a gas containing bromine as an etching gas was supplied into the growth chamber before re-growth to remove a part of the surface of the substrate to be grown. Therefore, a semiconductor light emitting device with high luminous efficiency can be obtained. That is, the gas containing bromine has an effect of etching a semiconductor layer such as GaAs. When the growth is interrupted and the Al-based residue remaining in the growth chamber is removed, an oxide film or the like may be formed on the epi-substrate surface. By supplying a gas containing bromine as an etching gas into the growth chamber before regrowth and providing a process for removing a part of the surface of the substrate to be grown, the oxide film and the like can be removed. An adverse effect on device characteristics such as light emission recombination can be suppressed, and a semiconductor light emitting device with high light emission efficiency can be obtained.
[Brief description of the drawings]
FIG. 1 is a graph showing the nitrogen composition dependence of threshold current density experimentally determined by the inventors of the present application.
FIG. 2 is a diagram showing an outline of a general MOCVD apparatus.
FIG. 3 is a diagram showing a room temperature photoluminescence spectrum of a GaInNAs / GaAs double quantum well structure (active layer) composed of a GaInNAs quantum well layer (a semiconductor layer containing nitrogen) and a GaAs barrier layer manufactured by an MOCVD apparatus.
4 is a diagram showing a sample structure used in the measurement of FIG. 3;
FIG. 5 shows an example of the semiconductor light emitting device shown in FIG. 4 in which a device in which a cladding layer is made of AlGaAs, an intermediate layer is made of GaAs, and an active layer is made of a GaInNAs / GaAs double quantum well structure is formed by one epitaxial growth apparatus (MOCVD). Is a diagram showing the distribution in the depth direction of the nitrogen (N) concentration and the oxygen (O) concentration.
FIG. 6 is a diagram showing a depth direction distribution of Al concentration of the same sample as FIG. 5;
FIG. 7 is a diagram showing a GaInNAs surface-emitting type semiconductor laser device according to the first embodiment of the present invention.
FIG. 8 is a diagram showing GaInNAs surface emitting semiconductor laser elements according to second, seventh and eighth embodiments of the present invention.
FIG. 9 is a diagram showing a GaInNAs surface-emitting type semiconductor laser device according to a third embodiment of the present invention.
FIG. 10 is a diagram showing a GaInNAs surface emitting semiconductor laser array (GaInNAs surface emitting semiconductor laser array chip) according to a fourth embodiment of the present invention.
FIG. 11 is a diagram illustrating an optical transmission module according to a fifth embodiment of the present invention.
FIG. 12 is a diagram showing an optical transceiver module according to a sixth embodiment of the present invention.

Claims (29)

A p-type semiconductor layer is provided between the active layer containing nitrogen and the semiconductor substrate, a selective oxidation layer containing Al and As is arranged in the p-type semiconductor layer, and a part of the arranged selective oxidation layer is formed A method of manufacturing a semiconductor light-emitting device that selectively oxidizes to form a current confinement structure, wherein a nitrogen compound raw material or a nitrogen compound raw material is formed between the growth of a selective oxidation layer and the start of growth of an active layer containing nitrogen. Semiconductor light emission characterized by providing a step of removing at least one of Al raw material, Al reactant, Al compound and Al remaining in a gas supply line or a growth chamber where an impurity contained therein is in contact Device manufacturing method.   2. The method of manufacturing a semiconductor light emitting device according to claim 1, wherein the nitrogen compound raw material or the impurities contained in the nitrogen compound raw material are in contact between the growth of the selective oxidation layer and the start of the growth of the active layer containing nitrogen. The process of removing at least one of the Al raw material, Al reactant, Al compound, and Al remaining in the gas supply line or in the growth chamber is interrupted and the gas supply line or growth chamber is purged with the carrier gas. A method for manufacturing a semiconductor light emitting device, characterized by comprising:   3. The method of manufacturing a semiconductor light emitting device according to claim 2, wherein a susceptor is baked during the growth interruption.   2. The method of manufacturing a semiconductor light emitting device according to claim 1, wherein the nitrogen compound raw material or the impurities contained in the nitrogen compound raw material are in contact between the growth of the selective oxidation layer and the start of the growth of the active layer containing nitrogen. The step of removing at least one of Al raw material, Al reactant, Al compound, and Al remaining in the gas supply line or in the growth chamber is a step of supplying an etching gas to the growth chamber. A method for manufacturing a semiconductor light emitting device.   5. The method of manufacturing a semiconductor light emitting device according to claim 4, wherein the etching gas is an organic nitrogen compound gas.   5. The method of manufacturing a semiconductor light emitting device according to claim 4, wherein the etching gas is a gas containing oxygen (O).   5. The method of manufacturing a semiconductor light emitting device according to claim 4, wherein the etching gas is a gas containing chlorine (Cl). A p-type semiconductor layer is provided between the active layer containing nitrogen and the semiconductor substrate, a selective oxidation layer containing Al and As is arranged in the p-type semiconductor layer, and a part of the arranged selective oxidation layer is formed Semiconductor light emission in which a current confinement structure is formed by selective oxidation, and at least one GaInPAs layer, GaInP layer, or GaPAs layer is formed between the selectively oxidized layer and the active layer containing nitrogen. A method for manufacturing an element, which is contained in a nitrogen compound raw material or a nitrogen compound raw material after the growth of a selective oxidation layer and until the growth of the GaInPAs layer, GaInP layer, or GaPAs layer is completed. A step of removing at least one of Al raw material, Al reactant, Al compound, and Al remaining in the gas supply line or the growth chamber where the impurities come into contact is provided. The method of manufacturing a semiconductor light-emitting device.   9. The method for manufacturing a semiconductor light emitting device according to claim 8, wherein the growth of the selective oxidation layer and the completion of the growth of the GaInPAs layer, the GaInP layer, or the GaPAs layer are completed. The step of removing at least one of the Al raw material, Al reactant, Al compound, and Al remaining in the gas supply line or the growth chamber where the impurities contained in the raw material come into contact is interrupted by the growth, and the carrier A method of manufacturing a semiconductor light emitting device, which is a step of purging a gas supply line or a growth chamber with a gas.   9. The method of manufacturing a semiconductor light emitting device according to claim 8, wherein a susceptor is baked during the growth interruption.   9. The method for manufacturing a semiconductor light emitting device according to claim 8, wherein the nitrogen compound raw material or the impurities contained in the nitrogen compound raw material are in contact between the growth of the selective oxidation layer and the start of the growth of the active layer containing nitrogen. The step of removing at least one of Al raw material, Al reactant, Al compound, and Al remaining in the gas supply line or in the growth chamber is a step of supplying an etching gas to the growth chamber. A method for manufacturing a semiconductor light emitting device.   9. The method of manufacturing a semiconductor light emitting device according to claim 8, wherein the etching gas is an organic nitrogen compound gas.   9. The method of manufacturing a semiconductor light emitting device according to claim 8, wherein the etching gas is a gas containing oxygen (O).   9. The method of manufacturing a semiconductor light emitting device according to claim 8, wherein the etching gas is a gas containing chlorine (Cl). A p-type semiconductor layer is provided between the active layer containing nitrogen and the semiconductor substrate, and a portion of the selectively oxidized layer containing Al and As disposed in the p-type semiconductor layer is selectively oxidized to narrow the current. In a semiconductor light emitting device having a structure, a semiconductor layer having a band gap larger than that of the active layer and containing nitrogen is formed between the selectively oxidized layer and the active layer containing nitrogen. A semiconductor light emitting device. 16. The semiconductor light emitting device according to claim 15 , wherein the semiconductor layer having a band gap larger than that of the active layer and containing nitrogen is any one of GaNAs, GaInNAs, GaInNP, GaNPAs, and GaInNPAs. 16. The semiconductor light emitting device according to claim 15 , wherein the band gap energy is larger between the semiconductor layer containing nitrogen and the active layer containing nitrogen than the active layer. A semiconductor light emitting element, wherein a layer made of any one of GaInPAs and GaInP is formed. An active region having nitrogen and an active region having a resonator structure including an active region having an active layer and upper and lower reflecting mirrors provided above and below the active layer to obtain laser light A method of manufacturing a surface-emitting type semiconductor laser device having a p-type semiconductor layer between a substrate and a semiconductor, wherein the lower reflecting mirror periodically changes the refractive index and reflects incident light by light wave interference A layer including a distributed Bragg reflector, wherein the semiconductor distributed Bragg reflector has a low refractive index is made of Al _x Ga _{1- x} As (0 <x ≦ 1), and the semiconductor distributed Bragg reflector has a high refractive index. The layer is made of Al _y Ga _{1- y} As (0 ≦ y <x ≦ 1), and selectively oxidized containing Al and As for selectively oxidizing part of the p-type semiconductor layer to perform current confinement. Active layer with selective oxidation layer and nitrogen And at least one GaInPAs layer, GaInP layer, or GaPAs layer is formed. After the selective oxidation layer is grown, the GaInPAs layer, the GaInP layer, or the GaPAs layer is grown. Until completion, at least one of Al source material, Al reactant, Al compound, and Al remaining in the gas supply line or the growth chamber where the nitrogen compound source material or impurities contained in the nitrogen compound source come into contact A method for manufacturing a surface-emitting type semiconductor laser device, comprising the step of removing one of the two. 19. The method for manufacturing a surface emitting semiconductor laser device according to claim 18, wherein the impurity contained in the nitrogen compound raw material or the nitrogen compound raw material is between the growth of the selective oxidation layer and the start of the growth of the active layer containing nitrogen. The process of removing at least one of the Al raw material, Al reactant, Al compound, and Al remaining in the gas supply line or in the growth chamber that is in contact with the growth is interrupted, and the gas supply line or growth is performed with a carrier gas. A method for manufacturing a surface-emitting type semiconductor laser device, which is a step of purging a chamber. 20. The method for manufacturing a surface emitting semiconductor laser element according to claim 19 , wherein a susceptor is baked during the growth interruption. An active region including nitrogen and an active region having a resonator structure including an active region having an active layer containing nitrogen, and an upper reflecting mirror and a lower reflecting mirror provided above and below the active layer in order to obtain laser light. A surface-emitting type semiconductor laser device having a p-type semiconductor layer between a substrate and a semiconductor reflector Bragg reflection in which the lower reflecting mirror periodically changes the refractive index and reflects incident light by light wave interference. includes a mirror, a layer having a smaller refractive index of the semiconductor distributed Bragg reflector Al _x Ga _1-x As made (0 <x ≦ 1), the layer having a large refractive index of the semiconductor distributed Bragg reflector Al _y Ga _{1- y} As (0 ≦ y <x ≦ 1), and has a selectively oxidized layer containing Al and As for selectively oxidizing part of the p-type semiconductor layer and performing current confinement. And between the selectively oxidized layer and the active layer containing nitrogen. The surface-emitting type semiconductor laser element, wherein the semiconductor layer band gap than the active layer comprises a large and nitrogen is formed. 23. The surface emitting semiconductor laser device according to claim 21, wherein the semiconductor layer having a band gap larger than that of the active layer and containing nitrogen is any one of GaNAs, GaInNAs, GaInNP, GaNPAs, and GaInNPAs. Type semiconductor laser device. 23. The surface-emitting type semiconductor laser device according to claim 21, wherein the band gap energy is larger between the semiconductor layer containing nitrogen and the active layer containing nitrogen between the semiconductor layer containing nitrogen and the active layer containing nitrogen than the active layer. , GaAsP, GaInPAs, GaInP, a surface emitting semiconductor laser element characterized in that a layer made of any one of them is formed. 24. A surface-emitting semiconductor laser array comprising a plurality of surface-emitting semiconductor laser elements according to claim 21 arranged in an array. 25. An optical transmission module comprising the surface-emitting type semiconductor laser device according to claim 21 or the surface-emitting type semiconductor laser array according to claim 24 as a light source. . 25. An optical transceiver module comprising the surface-emitting semiconductor laser element according to claim 21 or the surface-emitting semiconductor laser array according to claim 24 as a light source. . 24. An optical communication system, wherein the surface-emitting type semiconductor laser element according to claim 21 or the surface-emitting type semiconductor laser array according to claim 24 is used as a light source. .   A method for manufacturing a semiconductor light emitting device, wherein a semiconductor layer containing Al is provided between a substrate and an active layer, and the growth of the active layer containing nitrogen is started after the semiconductor layer containing Al is grown. Previously, a process of supplying a gas containing bromine as an etching gas into the growth chamber and removing at least one of Al raw material, Al reactant, Al compound, and Al remaining in the growth chamber is provided. A method for manufacturing a semiconductor light emitting device.   A method for manufacturing a semiconductor light emitting device, wherein a semiconductor layer containing Al is provided between a substrate and an active layer, and the growth of the active layer containing nitrogen is started after the semiconductor layer containing Al is grown. Semiconductor light emission characterized by providing a step of removing a part of the surface of the substrate to be grown by interrupting growth once and supplying a gas containing bromine as an etching gas into the growth chamber before re-growth. Device manufacturing method.

Images