JP2008098682A - Semiconductor light emitting element - Google Patents

Semiconductor light emitting element Download PDF

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JP2008098682A
JP2008098682A JP2008001177A JP2008001177A JP2008098682A JP 2008098682 A JP2008098682 A JP 2008098682A JP 2008001177 A JP2008001177 A JP 2008001177A JP 2008001177 A JP2008001177 A JP 2008001177A JP 2008098682 A JP2008098682 A JP 2008098682A
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Shunichi Sato
俊一 佐藤
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Ricoh Co Ltd
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<P>PROBLEM TO BE SOLVED: To provide a high-performance and long wavelength semiconductor light emitting element in which the impairment of crystallinity is prevented. <P>SOLUTION: In a semiconductor light emitting element having an active layer 3 including a strained quantum well layer 2, and a clad layer 4 for confining light and a carrier formed on a semiconductor substrate 1 and having an oscillation wavelength in a 1.3 μm band, the strained quantum well layer 2 contains In and N, an N composition occupies 0-1% of a group V element, an In composition occupies 30% or more of a group III element, and the amount of the strain of the strained quantum well layer 2 for the semiconductor substrate 1 and the clad layer 4 exceeds 2%. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

本発明は、半導体発光素子に関する。   The present invention relates to a semiconductor light emitting device.

従来、光ファイバーを用いた光通信システムは、主に幹線系で用いられているが、将来は各家庭を含めた加入者系での利用が考えられている。これを実現するためにはシステムの小型化,低コスト化が必要であり、光通信に用いられる半導体発光素子の温度制御用のペルチェ素子が不要なシステムの実現が必要である。   Conventionally, an optical communication system using an optical fiber is mainly used in a trunk system, but in the future, it is considered to be used in a subscriber system including each home. In order to realize this, it is necessary to reduce the size and cost of the system, and it is necessary to realize a system that does not require a Peltier element for temperature control of a semiconductor light emitting element used for optical communication.

このような光通信システムを実現するため、光通信に用いられる半導体発光素子には、低閾値動作と温度変化による特性変化の少ない高特性温度の素子が望まれている。一般に、半導体基板上に、半導体基板と格子定数が異なる材料を形成する場合、格子定数の相違に伴なう歪みから見積もられる臨界膜厚以下までの厚さを形成することができる。しかし、従来のGaInPAs/InP系材料では、伝導帯のバンド不連続を大きくできる材料が見あたらず、高特性温度を実現するのは困難であった。   In order to realize such an optical communication system, a semiconductor light emitting device used for optical communication is desired to have a high characteristic temperature element with low threshold operation and little characteristic change due to temperature change. In general, when a material having a lattice constant different from that of a semiconductor substrate is formed on a semiconductor substrate, a thickness up to a critical film thickness estimated from a strain associated with the difference in lattice constant can be formed. However, in the conventional GaInPAs / InP-based materials, there is no material that can increase the band discontinuity of the conduction band, and it has been difficult to achieve a high characteristic temperature.

これを改善するために、例えば特許文献1には、GaInAsからなる3元基板上に活性層が形成された半導体発光素子が提案されている。この半導体発光素子では、基板にGaInAsが用いられていることから、GaInAs基板上にワイドギャップの材料を形成できるので、InP基板上では実現できなかった大きな伝導帯のバンド不連続を得ることができる。   In order to improve this, for example, Patent Document 1 proposes a semiconductor light emitting element in which an active layer is formed on a ternary substrate made of GaInAs. In this semiconductor light emitting device, since GaInAs is used for the substrate, a wide gap material can be formed on the GaInAs substrate, so that it is possible to obtain band discontinuity of a large conduction band that could not be realized on the InP substrate. .

また、GaAs基板上に長波長レーザを形成する試みもなされている。特許文献2には、GaAs基板上にGaAsより格子定数の大きいGaInAs格子緩和バッファー層を形成し、その上に活性層を形成した半導体レーザ装置が提案されている。この半導体レーザ装置では、GaInAs格子緩和バッファー層上にGaAsより大きな格子定数の材料を形成することができるため、特許文献1に提案されている半導体発光素子と同様に、大きな伝導帯のバンド不連続を得ることができる。   Attempts have also been made to form long wavelength lasers on GaAs substrates. Patent Document 2 proposes a semiconductor laser device in which a GaInAs lattice relaxation buffer layer having a lattice constant larger than that of GaAs is formed on a GaAs substrate, and an active layer is formed thereon. In this semiconductor laser device, since a material having a lattice constant larger than that of GaAs can be formed on the GaInAs lattice relaxation buffer layer, as in the semiconductor light emitting device proposed in Patent Document 1, the band discontinuity of a large conduction band is achieved. Can be obtained.

また、GaAs基板上には、InP基板上やGaInAs3元基板上に形成される材料よりもワイドギャップの材料を形成できる。しかしながら、従来では、1.3μm帯等の長波長に対応するバンドギャップの活性層材料がなかった。すなわち、GaAs基板上にGaInAsを形成する場合、GaInAsは、In組成の増加で長波長化するが、歪み量の増加をともなう。その限界歪み量が約2%程度であるため、1.1μmの波長が限界であると言われている(非特許文献1)。   Further, a material having a wider gap than that formed on the InP substrate or the GaInAs ternary substrate can be formed on the GaAs substrate. However, conventionally, there has been no band gap active layer material corresponding to a long wavelength such as a 1.3 μm band. That is, when GaInAs is formed on a GaAs substrate, GaInAs increases in wavelength with an increase in In composition, but with an increase in strain. Since the limit strain is about 2%, it is said that the wavelength of 1.1 μm is the limit (Non-Patent Document 1).

そこで他の方法として、特許文献3には、GaAs基板上にGaInNAs系材料を形成することが提案されている。GaInNAsはNと他のV族元素を含んだIII−V族混晶半導体である。GaAs基板上にGaInNAs系材料を形成する場合、GaAsより格子定数が大きいGaInAsにNを添加することで、格子定数をGaAsに格子整合させることが可能となり、さらにNの電気陰性度が他の元素に比べて大きいことに起因して、そのバンドギャップエネルギーが小さくなり、1.3μm,1.5μm帯での発光が可能となる。非特許文献2には、近藤らによりバンドラインナップが計算されている。GaAs基板上にGaInNAs系材料を形成する場合には、上述のようにGaAs格子整合系となるので、ワイドギャップのAlGaAsをクラッド層に用いることができる。また、Nの添加により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るので、ヘテロ接合における伝導帯のバンド不連続が大きくなる。このため、高特性温度半導体発光素子が実現できると予想されている。   Therefore, as another method, Patent Document 3 proposes forming a GaInNAs-based material on a GaAs substrate. GaInNAs is a group III-V mixed crystal semiconductor containing N and other group V elements. When a GaInNAs material is formed on a GaAs substrate, it is possible to lattice-match the lattice constant to GaAs by adding N to GaInAs, which has a larger lattice constant than GaAs. The band gap energy is reduced due to the fact that the band gap energy is small compared to the above, and light emission in the 1.3 μm and 1.5 μm bands becomes possible. In Non-Patent Document 2, a band lineup is calculated by Kondo et al. When a GaInNAs material is formed on a GaAs substrate, a GaAs lattice matching system is used as described above, so that wide gap AlGaAs can be used for the cladding layer. In addition, the addition of N reduces the band gap and decreases the energy levels of the conduction band and valence band, thereby increasing the band discontinuity of the conduction band at the heterojunction. For this reason, it is expected that a high characteristic temperature semiconductor light emitting device can be realized.

GaInNAsレーザの構造に関しては、端面発光型については、特許文献4や特許文献5に提案がなされ、また、面発光型については、特許文献6や特許文献7に提案がなされている。そして、近年、GaAs基板上の1.3μm−GaInNAsレーザは実際に実現されている。すなわち、GaAs基板上に格子整合する窒素組成3%,In組成10%の厚膜GaInNAsを活性層としたダブルヘテロ構造(非特許文献3)や、窒素組成1%,In組成30%のGaInNAsを用いた圧縮歪み単一量子井戸構造(非特許文献4)が提案されている。
特開平6−275914号公報 特開平7−193327号公報 特開平6−37355号公報 特開平8−195522号公報 特開平10−126004号公報 特開平9−237942号公報 特開平10−74979号公報 IEEE Photonics. Technol. Lett.Vol.9 (1997) pp.1319-1321 Jpn.J.Appl.Phys.Vol.35 (1996)pp.1273-1275 Elecron. Lett. Vol.33 (1997) pp.1386-1387 IEEE Photonics. Technol. Lett.Vol.10 (1998) pp.487-488
Regarding the structure of the GaInNAs laser, the edge emitting type is proposed in Patent Document 4 and Patent Document 5, and the surface emitting type is proposed in Patent Document 6 and Patent Document 7. In recent years, a 1.3 μm-GaInNAs laser on a GaAs substrate has been actually realized. In other words, a double heterostructure (non-patent document 3) using a thick film GaInNAs having a nitrogen composition of 3% and an In composition of 10% that is lattice-matched on the GaAs substrate (non-patent document 3), or a GaInNAs having a nitrogen composition of 1% and an In composition of 30%. The compression strain single quantum well structure (nonpatent literature 4) used is proposed.
JP-A-6-275914 JP-A-7-193327 JP-A-6-37355 JP-A-8-195522 JP-A-10-126044 Japanese Patent Laid-Open No. 9-237942 Japanese Patent Laid-Open No. 10-74979 IEEE Photonics. Technol. Lett. Vol.9 (1997) pp.1319-1321 Jpn.J.Appl.Phys.Vol.35 (1996) pp.1273-1275 Elecron. Lett. Vol.33 (1997) pp.1386-1387 IEEE Photonics. Technol. Lett. Vol.10 (1998) pp.487-488

しかしながら、特許文献1に提案されているGaInAsからなる3元基板は、作成が困難である。また、特許文献2に提案されているGaInAs格子緩和バッファー層を形成した構造は、基本的に基板に対して格子不整合系なので寿命の点で問題がある。また、GaInNAsのような窒素と他のV族元素を含んだIII−V族混晶半導体は、窒素組成が大きくなるほど結晶性が大きく劣化するという問題があった。   However, the ternary substrate made of GaInAs proposed in Patent Document 1 is difficult to produce. Further, the structure in which the GaInAs lattice relaxation buffer layer proposed in Patent Document 2 is basically a lattice mismatch system with respect to the substrate has a problem in terms of lifetime. In addition, a group III-V mixed crystal semiconductor containing nitrogen and other group V elements such as GaInNAs has a problem that the crystallinity is greatly deteriorated as the nitrogen composition is increased.

本発明は、結晶性の劣化が防止された高性能な長波長の半導体発光素子を提供することを目的としている。   An object of the present invention is to provide a high-performance long-wavelength semiconductor light-emitting element in which deterioration of crystallinity is prevented.

上記目的を達成するために、請求項1記載の発明は、半導体基板上に、歪み量子井戸層を含む活性層と、光とキャリアを閉じ込めるクラッド層とが形成され、発振波長が1.3μm帯の半導体発光素子において、前記歪み量子井戸層はInとNを含み、V族元素に占めるN組成は0〜1%であり、III族元素に占めるIn組成は30%より大きい範囲であり、半導体基板およびクラッド層に対する前記歪み量子井戸層の歪み量が2%を超える歪み量となっていることを特徴としている。   In order to achieve the above object, according to the first aspect of the present invention, an active layer including a strained quantum well layer and a cladding layer for confining light and carriers are formed on a semiconductor substrate, and an oscillation wavelength is in a 1.3 μm band. In the semiconductor light emitting device, the strained quantum well layer contains In and N, the N composition in the group V element is 0 to 1%, and the In composition in the group III element is in a range larger than 30%. The strain amount of the strained quantum well layer with respect to the substrate and the cladding layer is characterized by a strain amount exceeding 2%.

また、請求項2記載の発明は、半導体基板上に、歪み量子井戸層を含む活性層と、光とキャリアを閉じ込めるクラッド層とが形成され、発振波長が1.3μm帯の半導体発光素子において、半導体基板およびクラッド層に対する前記歪み量子井戸層の歪み量が2%を超える歪み量となっており、半導体基板の面方位は、(100)からの傾き角度が5°の範囲内となっていることを特徴としている。   According to a second aspect of the present invention, an active layer including a strained quantum well layer and a clad layer for confining light and carriers are formed on a semiconductor substrate, and a semiconductor light emitting device having an oscillation wavelength of 1.3 μm band, The strain quantity of the strain quantum well layer with respect to the semiconductor substrate and the clad layer is greater than 2%, and the plane orientation of the semiconductor substrate is within a range of 5 ° from (100). It is characterized by that.

また、請求項3記載の発明は、請求項1または請求項2記載の半導体発光素子において、前記クラッド層としてGaInPまたはGaInPAsが用いられることを特徴としている。   According to a third aspect of the present invention, in the semiconductor light emitting device according to the first or second aspect, GaInP or GaInPAs is used as the cladding layer.

また、請求項4記載の発明は、請求項1または請求項2記載の半導体発光素子において、該半導体発光素子は、面発光型であることを特徴としている。   According to a fourth aspect of the present invention, in the semiconductor light-emitting device according to the first or second aspect, the semiconductor light-emitting device is a surface-emitting type.

また、請求項5記載の発明は、請求項1または請求項2記載の半導体発光素子において、前記活性層には、前記歪み量子井戸層の近傍に、応力を補償するバリア層が形成されていることを特徴としている。   According to a fifth aspect of the present invention, in the semiconductor light emitting device according to the first or second aspect, a barrier layer for compensating stress is formed in the active layer in the vicinity of the strained quantum well layer. It is characterized by that.

請求項1乃至請求項5記載の発明によれば、発振波長が1.3μm帯の半導体発光素子において、半導体基板およびクラッド層に対する前記歪み量子井戸層の歪み量が2%を超える歪み量となっているので、結晶性の改善を図ることができる。   According to the first to fifth aspects of the present invention, in the semiconductor light emitting device having the oscillation wavelength of 1.3 μm band, the strain amount of the strain quantum well layer with respect to the semiconductor substrate and the cladding layer is greater than 2%. Therefore, the crystallinity can be improved.

特に、請求項3記載の発明によれば、請求項1または請求項2記載の半導体発光素子において、クラッド層としてGaInPまたはGaInPAsが用いられており、Alを含まないGaInPまたはGaInPAsはAlGaAsに比べて低い成長温度で良好な結晶を得ることができるので、低温成長が好ましい高歪みの量子井戸レーザを作製する場合、拡散などの熱の影響を受けにくいので好ましく、結晶性の良好な高歪みの量子井戸層を得やすい。また、半導体基板と大きい歪みを有する量子井戸活性層との間の下部クラッド層としてGaInP(As)を用いるとクラッド層中で発生する欠陥の影響を受けにくく良好な大きい歪みの量子井戸層を成長できる。また、素子特性としてはクラッド層中で発生する欠陥の影響を受けにくいので、AlGaAs系材料を用いた場合に比べて発光効率は高く、長寿命の素子が得られる。また、レーザの場合しきい値電流密度は低い。   In particular, according to the invention described in claim 3, in the semiconductor light emitting device according to claim 1 or 2, GaInP or GaInPAs is used as the cladding layer, and GaInP or GaInPAs containing no Al is more than AlGaAs. Since a good crystal can be obtained at a low growth temperature, it is preferable to produce a high strain quantum well laser that is preferably grown at a low temperature because it is not easily affected by heat such as diffusion, and a high strain quantum well with good crystallinity. It is easy to obtain a well layer. In addition, when GaInP (As) is used as the lower cladding layer between the semiconductor substrate and the quantum well active layer having a large strain, a quantum well layer having a good large strain that is not easily affected by defects generated in the cladding layer is grown. it can. Further, since the element characteristics are not easily affected by defects generated in the clad layer, the light emitting efficiency is higher than that in the case of using an AlGaAs material, and an element having a long life can be obtained. In the case of a laser, the threshold current density is low.

また、請求項4記載の発明によれば、請求項1または請求項2記載の半導体発光素子において、該半導体発光素子は、面発光型である。すなわち、長波長帯の半導体発光素子はGaAs基板上に形成できると屈折率差の大きいAl(Ga)As/GaAs多層膜ミラーを用いることができるので、薄い厚さで済み、また、AlAsを酸化したAlxyを電流狭さくに用いることができるなど、従来のInP基板上の長波長帯の面発光半導体発光素子に比べて極めて有効である。 According to a fourth aspect of the present invention, in the semiconductor light emitting device according to the first or second aspect, the semiconductor light emitting device is a surface light emitting type. That is, when a semiconductor light emitting device of a long wavelength band can be formed on a GaAs substrate, an Al (Ga) As / GaAs multilayer mirror having a large refractive index difference can be used, so that a thin thickness is sufficient, and AlAs is oxidized. Al x O y can be used to narrow the current, and is extremely effective as compared with a conventional long-wavelength surface emitting semiconductor light emitting device on an InP substrate.

また、請求項5記載の発明によれば、請求項1または請求項2記載の半導体発光素子において、前記活性層には、前記歪み量子井戸層の近傍に、応力を補償するバリア層が形成されており、井戸層の歪みを緩和するバリア層(歪補償層)があると井戸層の質を改善したり、井戸層の数を多くしたりできるので、半導体発光素子の設計の幅を大きくでき、高性能化に最適な構造にでき有効である。特に、請求項5記載の発明では、井戸層が高圧縮歪を有している場合に応力を補償することで、作製する場合の条件の幅を広げることができる。
According to a fifth aspect of the present invention, in the semiconductor light emitting device according to the first or second aspect, a barrier layer for compensating stress is formed in the active layer in the vicinity of the strained quantum well layer. If there is a barrier layer (strain compensation layer) that alleviates strain in the well layer, the quality of the well layer can be improved and the number of well layers can be increased. It is effective because the structure can be optimized for high performance. In particular, in the invention described in claim 5, when the well layer has a high compressive strain, it is possible to widen the range of conditions for manufacturing by compensating the stress.

以下、本発明の実施形態を図面に基づいて説明する。   Hereinafter, embodiments of the present invention will be described with reference to the drawings.

図1は本発明に係る半導体発光素子の構成例を示す図である。図1の半導体発光素子(半導体レーザ)は、半導体基板1上に、歪み量子井戸層(発光層)2を含む活性層3と、光とキャリアを閉じ込めるクラッド層4とが形成されており、半導体基板1およびクラッド層4に対する歪み量子井戸層2の歪み量が2%を超える歪み量となっている。   FIG. 1 is a diagram showing a configuration example of a semiconductor light emitting device according to the present invention. In the semiconductor light emitting device (semiconductor laser) shown in FIG. 1, an active layer 3 including a strained quantum well layer (light emitting layer) 2 and a clad layer 4 for confining light and carriers are formed on a semiconductor substrate 1. The strain amount of the strained quantum well layer 2 with respect to the substrate 1 and the clad layer 4 is greater than 2%.

ここで、半導体基板1にはGaAsが用いられている。また、クラッド層4としてはGaInPまたはGaInPAsが用いられる。また、図1の半導体発光素子(半導体レーザ)は、面発光型のものとなっている。   Here, GaAs is used for the semiconductor substrate 1. Further, GaInP or GaInPAs is used as the cladding layer 4. Further, the semiconductor light emitting device (semiconductor laser) of FIG. 1 is a surface emitting type.

また、図1の半導体発光素子(半導体レーザ)において、歪み量子井戸層2は、GaxIn1-xyAs1-y(0≦x≦1,0≦y<1)で形成されている。そして、歪み量子井戸層2であるGaxIn1-xyAs1-y(0≦x≦1,0≦y<1)に関し、窒素が含まれていないとした場合のGaInAsの組成波長が、1.12μmよりも長波長となっている。より具体的に、歪み量子井戸層2のIII族元素に占めるInの組成は、30%よりも大きいものとなっている。また、歪み量子井戸層2のV族元素に占める窒素組成は、0〜1%の範囲となっている。 Further, in the semiconductor light emitting device (semiconductor laser) of FIG. 1, the strained quantum well layer 2 is formed of Ga x In 1 -x Ny As 1 -y (0 ≦ x ≦ 1, 0 ≦ y <1). Yes. Then, regarding Ga x In 1-x N y As 1-y (0 ≦ x ≦ 1, 0 ≦ y <1) which is the strained quantum well layer 2, the composition wavelength of GaInAs when nitrogen is not included However, the wavelength is longer than 1.12 μm. More specifically, the composition of In in the group III element of the strained quantum well layer 2 is greater than 30%. Further, the nitrogen composition in the group V element of the strained quantum well layer 2 is in the range of 0 to 1%.

また、図1の半導体発光素子(半導体レーザ)において、半導体基板1の面方位は、(100)からの傾き角度が5°の範囲内となっている。   Further, in the semiconductor light emitting device (semiconductor laser) of FIG. 1, the plane orientation of the semiconductor substrate 1 is within a range of an inclination angle of 5 ° from (100).

また、図1の半導体発光素子(半導体レーザ)において、活性層3には、歪み量子井戸層2の近傍に、応力を補償するバリア層が形成されている。図2はバリア層が形成された活性層の一例を示す図であり、図2の例では、活性層3には、井戸層2a,2bと、井戸層2a,2bの間および井戸層2aの下方および井戸層2bの上方に設けられたGaNPAsバリア層5a,5b,5cとが形成されている。   In the semiconductor light emitting device (semiconductor laser) shown in FIG. 1, a barrier layer for compensating stress is formed in the active layer 3 in the vicinity of the strained quantum well layer 2. FIG. 2 is a diagram showing an example of an active layer in which a barrier layer is formed. In the example of FIG. 2, the active layer 3 includes well layers 2a and 2b, well layers 2a and 2b, and well layers 2a. GaNPAs barrier layers 5a, 5b, and 5c provided below and well layer 2b are formed.

本発明では、半導体基板1上に、歪み量子井戸層2を含む活性層3と、光とキャリアを閉じ込めるクラッド層4とが形成されている半導体発光素子(半導体レーザ)において、半導体基板1およびクラッド層4に対する歪み量子井戸層2の歪み量が2%を超える歪み量であり、従来得られない材料組成を結晶成長することにより、従来得られない波長の半導体発光素子(半導体レーザ)を得ることができる。   In the present invention, in a semiconductor light emitting device (semiconductor laser) in which an active layer 3 including a strained quantum well layer 2 and a clad layer 4 for confining light and carriers are formed on a semiconductor substrate 1, the semiconductor substrate 1 and the clad The strain amount of the strain quantum well layer 2 with respect to the layer 4 is greater than 2%, and a semiconductor light emitting device (semiconductor laser) having a wavelength that cannot be obtained conventionally is obtained by crystal growth of a material composition that cannot be obtained conventionally. Can do.

また、半導体基板1がGaAs基板であることにより、InP基板上には厚く成長できないAlGaAs,AlAs,GaInP,AlInPのようなワイドギャップの材料を半導体発光素子のクラッド層として成長でき、長波長帯の半導体発光素子(半導体レーザ)の基板としては極めて優れている。   Further, since the semiconductor substrate 1 is a GaAs substrate, a wide gap material such as AlGaAs, AlAs, GaInP, and AlInP that cannot be grown thickly on the InP substrate can be grown as a cladding layer of the semiconductor light emitting device, and a long wavelength band can be obtained. It is extremely excellent as a substrate for semiconductor light emitting devices (semiconductor lasers).

また、図1の半導体発光素子(半導体レーザ)では、歪み量子井戸層2は、GaxIn1-xyAs1-y(0≦x≦1,0≦y<1)で形成されているので、y=0のGaInAsでは1.2μm程度までの波長、GaInNAsではIn組成,窒素組成に応じて1.3μm帯やそれより長波長の半導体発光素子(半導体レーザ)の発光層を形成できる。 Further, in the semiconductor light emitting device (semiconductor laser) of FIG. 1, the strained quantum well layer 2 is formed of Ga x In 1 -x N y As 1 -y (0 ≦ x ≦ 1, 0 ≦ y <1). Therefore, it is possible to form a light emitting layer of a semiconductor light emitting device (semiconductor laser) having a wavelength up to about 1.2 μm with GaInAs with y = 0, and with a wavelength of 1.3 μm or longer depending on the In composition and nitrogen composition with GaInNAs. .

また、歪み量子井戸層であるGaxIn1-xyAs1-y(0≦x≦1,0≦y<1)に関し、窒素が含まれていないとした場合のGaInAsのPL(Photoluminescence)波長が、1.12μmよりも長波長となっているので、従来半導体発光素子(半導体レーザ)の発光層に用いることができなかった組成波長の材料を結晶成長することにより、半導体発光素子(半導体レーザ)構造の設計の自由度を広げることができる。具体的には、y=0のGaInAsではInの組成を30%以上とすることで従来の限界であった1.1μmより長波長の半導体発光素子(半導体レーザ)が得られ、GaInNAsではInの組成を30%以上とすることで窒素の組成を従来より低減できる。例えば1.3μm帯を得る場合には窒素組成を1%以下にできる。 Further, regarding Ga x In 1-x N y As 1-y (0 ≦ x ≦ 1, 0 ≦ y <1), which is a strained quantum well layer, PL (Photoluminescence of GaInAs when no nitrogen is contained. Since the wavelength is longer than 1.12 μm, crystal growth of a material having a composition wavelength that could not be used for the light emitting layer of the conventional semiconductor light emitting device (semiconductor laser) allows the semiconductor light emitting device ( The degree of freedom in designing the (semiconductor laser) structure can be expanded. Specifically, in GaInAs with y = 0, by setting the In composition to 30% or more, a semiconductor light emitting device (semiconductor laser) having a wavelength longer than the conventional limit of 1.1 μm can be obtained. By setting the composition to 30% or more, the composition of nitrogen can be reduced as compared with the prior art. For example, in the case of obtaining a 1.3 μm band, the nitrogen composition can be made 1% or less.

また、図1の半導体発光素子(半導体レーザ)では、歪み量子井戸層2のV族元素に占める窒素組成が、0〜1%の範囲となっており、窒素組成が0〜1%の少ない範囲であると結晶性の低下は抑えられるので、高性能な長波長帯半導体発光素子(半導体レーザ)を得ることができる。   Further, in the semiconductor light emitting device (semiconductor laser) of FIG. 1, the nitrogen composition in the group V element of the strained quantum well layer 2 is in the range of 0 to 1%, and the nitrogen composition is in the small range of 0 to 1%. If this is the case, the decrease in crystallinity can be suppressed, so that a high-performance long wavelength band semiconductor light emitting device (semiconductor laser) can be obtained.

また、図1の半導体発光素子(半導体レーザ)では、半導体基板1の面方位は、(100)からの傾き角度が5°の範囲内であり、半導体基板の面方位は(100)から大きく傾いている(例えば[011]方向に大きく傾いている)よりは、(100)付近の方が歪み量子井戸のGaInNAsやGaInAsのIn組成を大きくしやすく長波長化に向いており、更に発光効率を高くしやすいので高歪みの量子井戸半導体発光素子(半導体レーザ)の基板に適している。   In the semiconductor light emitting device (semiconductor laser) of FIG. 1, the plane orientation of the semiconductor substrate 1 is within a range of an inclination angle of 5 ° from (100), and the plane orientation of the semiconductor substrate is greatly tilted from (100). (For example, it is more inclined in the [011] direction), it is easier to increase the In composition of GaInNAs and GaInAs in the strained quantum well in the vicinity of (100), and it is suitable for longer wavelengths, and further improves the luminous efficiency. Since it is easy to make it high, it is suitable for a substrate of a highly strained quantum well semiconductor light emitting device (semiconductor laser).

また、図1の半導体発光素子(半導体レーザ)では、クラッド層4としてGaInPまたはGaInPAsが用いられており、Alを含まないGaInPまたはGaInAsはAlGaAsに比べて低い成長温度で良好な結晶を得ることができるので、低温成長が好ましい高歪みの量子井戸レーザを作製する場合好ましく、結晶性の良好な高歪みの量子井戸層を得やすい。   Further, in the semiconductor light emitting device (semiconductor laser) of FIG. 1, GaInP or GaInPAs is used as the cladding layer 4, and GaInP or GaInAs not containing Al can obtain a good crystal at a lower growth temperature than AlGaAs. Therefore, it is preferable in the case of manufacturing a high strain quantum well laser in which low temperature growth is preferable, and it is easy to obtain a high strain quantum well layer having good crystallinity.

また、図1の半導体発光素子(半導体レーザ)が面発光型である場合、長波長帯の半導体発光素子(半導体レーザ)はGaAs基板上に形成できると屈折率差の大きいAl(Ga)As/GaAs多層膜ミラーを用いることができるので、薄い厚さで済み、また、AlAsを酸化したAlを電流狭さくに用いることができるなど、従来のInP基板上の長波長帯の面発光半導体発光素子(半導体レーザ)に比べて極めて有効である。 In addition, when the semiconductor light emitting device (semiconductor laser) of FIG. 1 is a surface emitting type, a long wavelength band semiconductor light emitting device (semiconductor laser) can be formed on a GaAs substrate and has a large refractive index difference. Since a GaAs multilayer mirror can be used, a thin thickness is sufficient, and Al x O y obtained by oxidizing AlAs can be used for current narrowing. It is extremely effective compared to a light emitting element (semiconductor laser).

また、図1の半導体発光素子(半導体レーザ)では、活性層3には、図2に示すように、歪み量子井戸層2a,2bの近傍に、応力を補償するバリア層(井戸層の歪みを緩和する歪補償層)5a,5b,5cが形成されており、井戸層の歪みを緩和する歪補償層があると、井戸層の質を改善したり、井戸層の数を多くしたりできるので、半導体発光素子(半導体レーザ)の設計の幅を大きくでき、高性能化に最適な構造にできて有効である。   Further, in the semiconductor light emitting device (semiconductor laser) of FIG. 1, the active layer 3 has a barrier layer (well layer strain compensated for stress) in the vicinity of the strained quantum well layers 2a and 2b, as shown in FIG. The strain compensation layers 5a, 5b, and 5c are formed. If there is a strain compensation layer that relaxes strain in the well layer, the quality of the well layer can be improved and the number of well layers can be increased. The design range of the semiconductor light emitting device (semiconductor laser) can be increased, and it is effective to have an optimum structure for high performance.

また、半導体基板1上に、歪み量子井戸層2を含む活性層3と、光とキャリアを閉じ込めるクラッド層4とを有する半導体発光素子(半導体レーザ)の製造方法において、低温では歪み量子井戸層2の臨界膜厚が厚くなるので、特に、歪み量が2%を超えるような高歪み量子井戸層の成長には、600℃以下の温度での低温成長が適している。   In a method for manufacturing a semiconductor light emitting device (semiconductor laser) having an active layer 3 including a strained quantum well layer 2 and a clad layer 4 that confines light and carriers on a semiconductor substrate 1, the strained quantum well layer 2 is formed at a low temperature. In particular, low temperature growth at a temperature of 600 ° C. or lower is suitable for the growth of a high strain quantum well layer in which the strain amount exceeds 2%.

また、III−V族半導体で形成される半導体発光素子(半導体レーザ)の場合、半導体発光素子は、III族原料として、有機金属化合物を用いた有機金属気相成長法により形成される。すなわち、有機金属気相成長法は、過飽和度が高い成長方法であり、高歪みの量子井戸層や窒素をV族に含んだGaInNAsのような材料の成長を行なうのに有効である。   In the case of a semiconductor light emitting device (semiconductor laser) formed of a III-V group semiconductor, the semiconductor light emitting device is formed by a metal organic vapor phase growth method using an organometallic compound as a group III material. That is, the metal organic vapor phase growth method is a growth method having a high degree of supersaturation, and is effective for growing a high strained quantum well layer or a material such as GaInNAs containing nitrogen in the V group.

また、歪み量子井戸層2をGaxIn1-xyAs1-y(0≦x≦1,0≦y<1)で形成する場合、Nの原料として、DMHy(ジメチルヒドラジン),MMHy(モノメチルヒドラジン)等の有機系窒素化合物を用いて形成する。すなわち、有機系窒素化合物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いる。また、本発明のように特に歪みの大きい量子井戸層を成長する場合は、例えば、500℃〜600℃程度の低温成長が好ましく、この観点からも低温で分解する有機系窒素化合物は好ましい。 Further, when the strained quantum well layer 2 is formed of Ga x In 1-x N y As 1-y (0 ≦ x ≦ 1, 0 ≦ y <1), DMHy (dimethylhydrazine), MMHy is used as a raw material of N It is formed using an organic nitrogen compound such as (monomethylhydrazine). That is, since organic nitrogen compounds decompose at low temperatures, they are suitable for low temperature growth at 600 ° C. or lower. Further, when a quantum well layer having a particularly large strain is grown as in the present invention, for example, low temperature growth of about 500 ° C. to 600 ° C. is preferable, and an organic nitrogen compound that decomposes at a low temperature is also preferable from this viewpoint.

前述のように、GaAs基板上のGaInAsは、In組成の増加で半導体発光素子(半導体レーザ)の発振波長を長波長化することができるが、歪み量の増加をともなう。その限界歪み量は、約2%程度であり、発振波長は1.1μmが限界であると言われている(文献「IEEEPhotonics. Technol. Lett.Vol.9 (1997) pp.1319-1321」)。   As described above, GaInAs on a GaAs substrate can increase the oscillation wavelength of a semiconductor light emitting device (semiconductor laser) by increasing the In composition, but it also increases the amount of distortion. The limit distortion is about 2%, and the oscillation wavelength is said to be 1.1 μm (refer to the document “IEEEPhotonics. Technol. Lett. Vol.9 (1997) pp.1319-1321”). .

下地の基板に対して格子定数の違う材料を成長すると、格子は弾性変形してそのエネルギーを吸収する。しかし、下地の基板に対して格子定数の違う材料を厚く成長していくと、弾性的な変形だけでは歪みエネルギーを吸収できずにミスフィット転位が生じてしまう。この膜厚を臨界膜厚という。ミスフィット転位が生じてしまうと、良いデバイスを作製することは困難である。   When a material having a different lattice constant is grown on the underlying substrate, the lattice elastically deforms and absorbs its energy. However, when a material having a different lattice constant is grown thicker than the underlying substrate, the strain energy cannot be absorbed only by elastic deformation, and misfit dislocation occurs. This film thickness is called critical film thickness. If misfit dislocations occur, it is difficult to produce a good device.

理論的には、力学的にミスフィット転位が生じる厚さである臨界膜厚(h)が、Matthews and Blakeslee(文献「J. Crystal Growth. 27 (1974) 118.」)によって次式により与えられている。 Theoretically, the critical film thickness (h c ), which is the thickness at which misfit dislocations are generated mechanically, is given by the following equation according to Matthews and Blakeslee (reference “J. Crystal Growth. 27 (1974) 118.”). It has been.

Figure 2008098682
Figure 2008098682

ここで、νは ポアソン比(ν = C12/(C11+C12);C11,C12は弾性スティフネス定数である)、αは界面でのバーガースベクトルと転位線の線分とのなす角(cos α = 1/2)、λは滑り面と界面の交差線に垂直な界面内での方向とバーガースベクトルとのなす角(cos λ = 1/2)、b = a/21/2 (a;格子定数)、fは格子不整合度(f = Δa/a)である。なお、数1は無限大の厚さの基板上に単層膜を成長する場合の式であり、以後、この式(数1)によって与えられる臨界膜厚hを、Matthews and Blakesleeの理論に基づく臨界膜厚と称す。 Here, ν is a Poisson's ratio (ν = C 12 / (C 11 + C 12 ); C 11 and C 12 are elastic stiffness constants), and α is an angle formed by a Burgers vector and a dislocation line segment at the interface. (Cos α = 1/2), λ is an angle (cos λ = 1/2) formed by the Burgers vector and the direction in the interface perpendicular to the intersecting line between the sliding surface and the interface, b = a / 2 1/2 (A: lattice constant), f is the degree of lattice mismatch (f = Δa / a). Equation (1) is an equation for growing a single layer film on an infinitely thick substrate. Hereinafter, the critical film thickness h c given by this equation (Equation 1) is expressed by Matthews and Blakeslee's theory. This is called the critical film thickness.

図14には、一般に支持されているMatthews and Blakesleeの理論に基づいて計算されたGaAs基板上のGaInAs層の臨界膜厚が示されている。なお、Ga1−xInAsに窒素を添加したGa1−xInNAsの格子定数は、窒素添加1%当たり、In組成xが3%小さいGa1−yInAs(y=x−0.03)とほぼ同じ格子定数となる。 FIG. 14 shows the critical film thickness of the GaInAs layer on the GaAs substrate calculated based on the generally supported Matthews and Blakeslee theory. Note that the lattice constant of Ga 1-x In x NAs obtained by adding nitrogen to Ga 1-x In x As is Ga 1-y In y As (y = x) where the In composition x is 3% smaller per 1% of nitrogen addition. The lattice constant is almost the same as that of -0.03).

GaAs基板上にGaInAsを形成する場合、In組成を増加すると歪み量が大きくなるので、平面に2次元で成長できる膜厚である臨界膜厚は薄くなっていく。   When GaInAs is formed on a GaAs substrate, the amount of strain increases as the In composition increases, so that the critical film thickness, which is a film that can be grown two-dimensionally on a plane, becomes thinner.

これに対し、本願の発明者は、GaAs基板上のGaInAs量子井戸層においてIn組成を30%を超える値とすることにより、GaAs基板に対する量子井戸層の歪み量を2%以上で成長でき、従来限界と考えられてきた1.1μm より長波長の半導体発光素子(半導体レーザ)が実現可能であることを見出した。更には、歪み量子井戸層2において、低温成長等の非平衡条件での成長により実質的な臨界膜厚hc’を、Matthews and Blakesleeの臨界膜厚hcを越えた厚さとすることが可能であり、これにより、1.2μmを越える長波長までの半導体発光素子(半導体レーザ)が実現可能であることを見出した。 On the other hand, the inventors of the present application can grow the strain amount of the quantum well layer with respect to the GaAs substrate by 2% or more by setting the In composition to a value exceeding 30% in the GaInAs quantum well layer on the GaAs substrate. It has been found that a semiconductor light emitting device (semiconductor laser) having a wavelength longer than 1.1 μm, which has been considered the limit, can be realized. Further, in the strained quantum well layer 2, the substantial critical film thickness h c ′ can be made to exceed the critical film thickness h c of Matthews and Blakeslee by growth under non-equilibrium conditions such as low temperature growth. Thus, it was found that a semiconductor light emitting device (semiconductor laser) having a long wavelength exceeding 1.2 μm can be realized.

すなわち、本願の発明者は、半導体基板上に、歪み量子井戸層を含む活性層と、光とキャリアを閉じ込めるクラッド層とが形成されている半導体発光素子において,半導体基板及びクラッド層に対する前記歪み量子井戸層の厚さがMatthews and Blakesleeの理論に基づく臨界膜厚hより厚い場合に、従来得られない波長の半導体レーザ等の半導体発光素子を得ることができ、また、従来より高性能のHEMT(high electron mobility transister)等の電子素子を得ることもできることを見出した。 That is, the inventor of the present application provides a semiconductor light emitting device in which an active layer including a strained quantum well layer and a cladding layer for confining light and carriers are formed on a semiconductor substrate. If the thickness of the well layer is thicker than the critical thickness h c based on the theory of Matthews and Blakeslee, it is possible to obtain a semiconductor light-emitting element such as a semiconductor laser of the prior art is not obtained wavelength, also, high-performance HEMT conventionally It has been found that an electronic device such as (high electron mobility transister) can be obtained.

図14には実験例が示されている。図14を参照すると、例えば、In組成32%、厚さ8.6nmの場合、PL中心波長は1.13μmであり、また、In組成36%、厚さ7.8nmの場合、PL中心波長は1.16μmであり、また、 In組成39%、厚さ7.2nmの場合、PL中心波長は1.2μmであった。これらは、Matthews and Blakesleeの理論(数1)に基づいて計算した臨界膜厚hcを越えた厚さとなっている。 FIG. 14 shows an experimental example. Referring to FIG. 14, for example, when the In composition is 32% and the thickness is 8.6 nm, the PL center wavelength is 1.13 μm, and when the In composition is 36% and the thickness is 7.8 nm, the PL center wavelength is When the In composition was 39% and the thickness was 7.2 nm, the PL center wavelength was 1.2 μm. These are thicknesses exceeding the critical film thickness h c calculated based on the theory of Matthews and Blakeslee (Equation 1).

図15には、GaInAs単一量子井戸層からのPL中心波長とPL強度との関係が示されている。GaInAs井戸層(図中実線部)のIn組成xは31%〜42%とした。また、各井戸層25a,25bの厚さは、In組成xの増加に合わせて、約9nm〜約6nmと薄くしていった。波長1.2μm程度までPL強度の強い量子井戸層が得られた。波長1.2μmまではPL強度は徐々に低下しているのに対して、1.2μmを越えると、PL強度は急激に低下していることがわかる。これは表面性にも対応しており1.2μmまでは鏡面であった。これらの結果から、PL強度の上記急激な低下は量子井戸層の厚さが実質的な臨界膜厚hc’を越えたためと考えられる。一般にMOCVD法やMBE法において低温成長、高い成長速度等の強い非平衡成長条件で、実験的に得られる臨界膜厚が増加することが報告されている。また成長条件(例えば高温成長)により、理論に基づく臨界膜厚より薄い厚さでも三次元成長、表面荒れが起こることも報告されている。よって本結果は、理論に基づく臨界膜厚hcよりも低温成長等の非平衡条件での成長による実質的な臨界膜厚hc’の方が厚いために、ミスフィット転位が生じることなく、より厚い膜を二次元に成長できたものと考えられる。 FIG. 15 shows the relationship between the PL center wavelength and the PL intensity from the GaInAs single quantum well layer. The In composition x of the GaInAs well layer (solid line portion in the figure) was 31% to 42%. The thickness of each well layer 25a, 25b was reduced to about 9 nm to about 6 nm in accordance with the increase of the In composition x. A quantum well layer having a strong PL intensity up to a wavelength of about 1.2 μm was obtained. It can be seen that the PL intensity gradually decreases up to a wavelength of 1.2 μm, whereas the PL intensity rapidly decreases beyond 1.2 μm. This also corresponds to the surface property, and was a mirror surface up to 1.2 μm. From these results, it is considered that the sudden decrease in the PL intensity is due to the fact that the thickness of the quantum well layer exceeds the substantial critical film thickness h c ′. In general, it has been reported that the critical film thickness obtained experimentally increases in MOCVD or MBE under strong non-equilibrium growth conditions such as low temperature growth and high growth rate. It has also been reported that, depending on the growth conditions (for example, high-temperature growth), three-dimensional growth and surface roughness occur even when the thickness is less than the critical thickness based on theory. Thus, the present results, the thicker the better substantial critical thickness h c 'by growth in non-equilibrium conditions of the low-temperature growth such than the critical film thickness h c based on theory without misfit dislocations occurs, It is considered that a thicker film could be grown in two dimensions.

さらに、本願の発明者は、GaInNAsレーザの場合、上記のようにIn組成xを大きくすることにより窒素組成を小さくできるため、GaInNAsレーザの特性を大きく改善できることを見出した。   Furthermore, the inventors of the present application have found that, in the case of a GaInNAs laser, since the nitrogen composition can be reduced by increasing the In composition x as described above, the characteristics of the GaInNAs laser can be greatly improved.

また、レーザ化する場合、クラッド層としてAlGaAsを用いるよりGaInP(As)を用いた方が容易に形成できることを見出した。その理由を以下に示す。   In addition, it has been found that when using laser, GaInP (As) can be formed more easily than using AlGaAs as the cladding layer. The reason is as follows.

すなわち、大きな歪みを有したGaInNAsやGaInAs活性層は低温(例えば600℃以下)で成長できる。しかしAlGaAsの成長温度は一般に高い(例えば700℃以上)。本願の発明者は、活性層成長後に、活性層の上部にAlGaAsクラッド層を成長することを想定して熱処理実験を行なった。具体的に、(100)GaAs基板上に、GaAs層(膜厚が0.2μm),GaInNAs井戸層(膜厚が7nm),GaAs層(膜厚が50nm)を順次に成長させた試料を4試料(a,b,c,d)作製した。4つの各試料a,b,c,dは、In組成は同じで窒素組成が違う。すなわち、試料aの窒素(N)組成は0.2%であり、試料bの窒素(N)組成は0.2%であり、試料cの窒素(N)組成は0.5%であり、試料dの窒素(N)組成は0.8%である。その後、MOCVD成長装置を用いてAsH3雰囲気中で、試料c,dについては680℃の温度で、また、試料bについては700℃の温度で、また、試料aについては780℃の温度で、30分間熱処理(アニ−ル)した。図12には、これらの試料a,b,c,dのPL特性が示されている。図12において、点線が熱処理前のスペクトルであり、実線が熱処理後のスペクトルである。熱処理によりピーク波長が短波長側にシフトし、熱処理温度が高い方がシフト量が大きいことがわかる。同じ温度では、窒素量が違う試料間(試料c,試料d)でシフト量は同じであり、このシフトの原因はInの拡散であると考えられる。また、発光強度は、780℃では低下しており、700℃以下では増加していることがわかる。発光強度の増加の原因は熱処理による活性層中の欠陥の減少と考えられ、低下の原因は結晶性の劣化と考えられる。 That is, a GaInNAs or GaInAs active layer having a large strain can be grown at a low temperature (for example, 600 ° C. or less). However, the growth temperature of AlGaAs is generally high (eg, 700 ° C. or higher). The inventor of the present application conducted a heat treatment experiment on the assumption that an AlGaAs cladding layer is grown on the active layer after the active layer is grown. Specifically, four samples were sequentially grown on a (100) GaAs substrate with a GaAs layer (film thickness 0.2 μm), a GaInNAs well layer (film thickness 7 nm), and a GaAs layer (film thickness 50 nm). Samples (a, b, c, d) were prepared. The four samples a, b, c, and d have the same In composition and different nitrogen compositions. That is, the nitrogen (N) composition of sample a is 0.2%, the nitrogen (N) composition of sample b is 0.2%, and the nitrogen (N) composition of sample c is 0.5%, Sample d has a nitrogen (N) composition of 0.8%. Thereafter, in an AsH 3 atmosphere using an MOCVD growth apparatus, the samples c and d were at a temperature of 680 ° C., the sample b was at a temperature of 700 ° C., and the sample a was at a temperature of 780 ° C. Heat treated (annealed) for 30 minutes. FIG. 12 shows the PL characteristics of these samples a, b, c, and d. In FIG. 12, the dotted line is the spectrum before the heat treatment, and the solid line is the spectrum after the heat treatment. It can be seen that the peak wavelength is shifted to the short wavelength side by the heat treatment, and the shift amount is larger as the heat treatment temperature is higher. At the same temperature, the shift amount is the same between samples with different amounts of nitrogen (sample c and sample d), and the cause of this shift is considered to be the diffusion of In. It can also be seen that the emission intensity decreases at 780 ° C. and increases at 700 ° C. or lower. The cause of the increase in emission intensity is considered to be a decrease in defects in the active layer due to heat treatment, and the cause of the decrease is considered to be deterioration of crystallinity.

このように大きな歪みを有したGaInNAsやGaInAs活性層を成長してから780℃のような高温で上部の層(例えばクラッド層)を成長すると不具合が生じることがわかった。このため上部クラッド層としては低温で良好に成長できるGaInP(As)が好ましい。ただしAlGaAsでも700℃以下の温度で成長すれば大きな問題はないので使用できる。   It has been found that when a GaInNAs or GaInAs active layer having such a large strain is grown, an upper layer (for example, a clad layer) is grown at a high temperature such as 780 ° C. For this reason, GaInP (As), which can be favorably grown at a low temperature, is preferable as the upper cladding layer. However, AlGaAs can be used because there is no major problem if it is grown at a temperature of 700 ° C. or lower.

もう一つの理由は、大きな歪みを有したGaInNAsやGaInAs活性層を成長する前にAlGaAsを成長すると活性層の品質を落しやすいことである。本願の発明者は、(100)GaAs基板上に、ガイド層(膜厚が0.2μm),GaAs層(膜厚が100nm),GaInNAs井戸層(膜厚が7nm),GaAs層(膜厚が100nm),ガイド層(膜厚が50nm)を順次成長した試料を2試料作製した。第1の試料は、ガイド層(クラッド層)としてGa0.5In0.5Pを用い(以下、GaInPを用いた試料と称す)、また、第2の試料は、ガイド層(クラッド層)としてAl0.4Ga0.6Asを用いた(以下、AlGaAsを用いた試料と称す)。GaInPを用いた試料の方がIn組成は大きく歪みが大きくなっている。図13には第1の試料(GaInP),第2の試料(AlGaAs)のPL特性が示されている。図13から、GaInPを用いた試料の方が歪みが大きく長波長であり、成長が困難であるにもかかわらず、AlGaAsを用いた試料よりもPL強度が強くなっていることがわかる。 Another reason is that if the AlGaAs is grown before the GaInNAs or GaInAs active layer having a large strain is grown, the quality of the active layer is easily deteriorated. The inventor of the present application has a guide layer (film thickness of 0.2 μm), a GaAs layer (film thickness of 100 nm), a GaInNAs well layer (film thickness of 7 nm), a GaAs layer (film thickness of 100 nm) and a guide layer (film thickness of 50 nm) were sequentially grown to prepare two samples. The first sample uses Ga 0.5 In 0.5 P as the guide layer (cladding layer) (hereinafter referred to as a sample using GaInP), and the second sample uses Al 0.4 Ga as the guide layer (cladding layer). 0.6 As was used (hereinafter referred to as a sample using AlGaAs). A sample using GaInP has a larger In composition and a larger strain. FIG. 13 shows the PL characteristics of the first sample (GaInP) and the second sample (AlGaAs). From FIG. 13, it can be seen that the sample using GaInP has a larger distortion than the sample using AlGaAs, although the distortion is longer and the wavelength is longer and the growth is difficult.

この原因としてはAlに起因した欠陥が成長中に成長表面に現れ、常に成長表面に伝搬し、GaInNAs井戸層まで到達し、井戸層を劣化させていることが考えられる。つまり、量子井戸活性層の成長直前のエピ基板表面の状態が良好でないと高品質に成長できないことがわかった。このため下部クラッド層としてAlGaAsを用いる場合は井戸層成長の前にこの欠陥を止める工夫をする必要がある。半導体基板と活性層との間のクラッド層としてAlを含まないGaInP(As)を用いると、量子井戸活性層の成長直前のエピ基板表面の状態は良好であり、大きい歪みの量子井戸層を容易に良好に成長できる。上述したようにクラッド層としては、特に、半導体基板と大きい歪みの活性層との間の下部クラッド層としては、GaInP(As)を用いる方が好ましいことがわかる。   As a cause of this, it is considered that defects caused by Al appear on the growth surface during growth, always propagate to the growth surface, reach the GaInNAs well layer, and deteriorate the well layer. In other words, it was found that the epitaxial substrate surface just before the growth of the quantum well active layer cannot be grown with high quality unless the surface state is good. For this reason, when AlGaAs is used as the lower cladding layer, it is necessary to devise a means to stop this defect before the well layer growth. When GaInP (As) containing no Al is used as the cladding layer between the semiconductor substrate and the active layer, the state of the epi-substrate surface immediately before the growth of the quantum well active layer is good, and a large strained quantum well layer can be easily formed. Can grow well. As described above, it is understood that GaInP (As) is preferably used as the cladding layer, particularly as the lower cladding layer between the semiconductor substrate and the active layer having a large strain.

さらに、本願の発明者は、GaAs基板の面方位は、(100)から大きく傾いている(例えば、(100)から[011]方向に大きく傾いている)よりは、(100)付近の方がIn組成を大きくし易いし、発光効率を高くし易く適していることを見出した。光通信で用いる1.3μm帯等の長波長での高品質なGaInNAsを得るための1つの方法は、GaInNAsにおいて、In組成を大きくして長波長化し、窒素組成を減らすことである。GaAs基板の面方位が(100)である場合と、基板の面方位が(100)から[011]方向に15°の角度で傾いている場合とのそれぞれの場合において、GaAs基板上に、Ga0.5In0.5P層(膜厚が0.2μm)と、GaAs層(膜厚が100nm)と、GaInNAs量子井戸層(発光層)(膜厚が7nm)およびGaAsバリア層(膜厚が13nm)からなる活性層と、GaAs層(膜厚が100nm)と、Ga0.5In0.5P層(膜厚が50nm)と、GaAs層(膜厚が50nm)とを順次に形成した。図3には、面方位が(100)であるGaAs基板上に形成された半導体発光素子のPL特性(符号Aで示す)と、面方位が(100)から〔011〕方向に15゜の角度で傾いているGaAs基板上に形成された半導体発光素子のPL特性(符号Bで示す)を示す。なお、面方位が(100)から〔011〕方向に15゜の角度で傾いているGaAs基板上に形成された半導体発光素子では、PL波長1.06μmのGaInAsに窒素添加している。一方、面方位が(100)であるGaAs基板上に形成された半導体発光素子では、PL波長1.13μmのGaInAsに窒素添加している。 Furthermore, the inventor of the present application indicates that the plane orientation of the GaAs substrate is more in the vicinity of (100) than in the case where the plane orientation is greatly inclined from (100) (for example, it is greatly inclined in the [011] direction from (100)). It has been found that the In composition is easily increased and the light emission efficiency is easily increased. One method for obtaining high-quality GaInNAs at a long wavelength such as the 1.3 μm band used in optical communication is to increase the In composition to increase the wavelength and reduce the nitrogen composition in GaInNAs. In each of the case where the plane orientation of the GaAs substrate is (100) and the case where the plane orientation of the substrate is inclined at an angle of 15 ° from the (100) direction to the [011] direction, Ga is formed on the GaAs substrate. From 0.5 In 0.5 P layer (film thickness is 0.2 μm), GaAs layer (film thickness is 100 nm), GaInNAs quantum well layer (light emitting layer) (film thickness is 7 nm) and GaAs barrier layer (film thickness is 13 nm) An active layer, a GaAs layer (with a film thickness of 100 nm), a Ga 0.5 In 0.5 P layer (with a film thickness of 50 nm), and a GaAs layer (with a film thickness of 50 nm) were sequentially formed. FIG. 3 shows a PL characteristic (indicated by reference symbol A) of a semiconductor light emitting device formed on a GaAs substrate having a plane orientation of (100) and an angle of 15 ° from the (100) to the [011] direction. 2 shows PL characteristics (indicated by symbol B) of a semiconductor light emitting device formed on a GaAs substrate tilted by. Note that in a semiconductor light emitting device formed on a GaAs substrate whose plane orientation is inclined at an angle of 15 ° from the (100) direction to the [011] direction, nitrogen is added to GaInAs having a PL wavelength of 1.06 μm. On the other hand, in a semiconductor light emitting device formed on a GaAs substrate having a plane orientation of (100), nitrogen is added to GaInAs having a PL wavelength of 1.13 μm.

図3から面方位が(100)であるGaAs基板上に形成された半導体発光素子の方が、長波長であるにもかかわらず発光強度が高くなっており、適していることがわかる。これに対し、面方位が(100)から〔011〕方向に15°の角度で傾いているGaAs基板上に形成された半導体発光素子では、In組成を大きくし1.06μmの波長よりも長波長化を試みたが、発光強度は著しく低下し、In組成を大きくすることは困難であった。一方、面方位が(100)であるGaAs基板上に形成された半導体発光素子では、GaInAsを用いて1.2μm程度の波長まで強い発光が観察された。このことから、GaAs基板の面方位の(100)からの傾き角度は、5°の範囲内であるのが好ましい。   As can be seen from FIG. 3, the semiconductor light emitting device formed on the GaAs substrate having the plane orientation of (100) has a higher light emission intensity despite the longer wavelength and is more suitable. In contrast, in a semiconductor light emitting device formed on a GaAs substrate whose plane orientation is inclined at an angle of 15 ° from the (100) direction to the [011] direction, the In composition is increased and the wavelength is longer than the wavelength of 1.06 μm. However, it was difficult to increase the In composition. On the other hand, in a semiconductor light emitting device formed on a GaAs substrate having a plane orientation of (100), strong light emission was observed up to a wavelength of about 1.2 μm using GaInAs. For this reason, it is preferable that the inclination angle of the plane orientation of the GaAs substrate from (100) is within a range of 5 °.

次に、実施例について説明する。   Next, examples will be described.

図4は実施例1の半導体発光素子を示す図である。ここでは、半導体発光素子として、最も簡単な構造である絶縁膜ストライプ型レーザを例にして説明する。図4の半導体発光素子は、層構造として、SCH−DQW(Separate Confinement Heterostructure Double Quantum Well)構造を有している。具体的に、図4の半導体発光素子は、面方位(100)のn−GaAs基板21上に、n−GaAsバッファ層22と、n−GaInP(As)下部クラッド層23(膜厚が1.5μm)と、GaAs光ガイド層24(膜厚が100nm)と、Ga1-xInxAs井戸層25a,25bおよびGaAsバリア層26(膜厚が13nm)からなる活性層(発光層)27と、GaAs光ガイド層28(膜厚が100nm)と、p−GaInP(As)上部クラッド層29(膜厚が1.5μm)と、p−GaAsコンタクト層30(膜厚が0.3μm)とが、順次に形成されている。また、図4の半導体発光素子では、GaAsコンタクト層30は電流注入部分以外はエッチングにより除去され、電流注入部となる部分を除去した絶縁膜31を介してp側電極32が形成されている。また、基板21の裏面にはn側電極33が形成されている。 4 is a diagram showing a semiconductor light emitting device of Example 1. FIG. Here, an insulating film stripe type laser having the simplest structure will be described as an example of the semiconductor light emitting element. The semiconductor light emitting device of FIG. 4 has a SCH-DQW (Separate Confinement Heterostructure Double Quantum Well) structure as a layer structure. Specifically, the semiconductor light emitting device of FIG. 4 has an n-GaAs buffer layer 22 and an n-GaInP (As) lower cladding layer 23 (with a film thickness of 1.. 5 μm), a GaAs light guide layer 24 (film thickness is 100 nm), an active layer (light emitting layer) 27 composed of Ga 1-x In x As well layers 25 a and 25 b and a GaAs barrier layer 26 (film thickness is 13 nm), , A GaAs light guide layer 28 (film thickness is 100 nm), a p-GaInP (As) upper cladding layer 29 (film thickness is 1.5 μm), and a p-GaAs contact layer 30 (film thickness is 0.3 μm). Are formed sequentially. Further, in the semiconductor light emitting device of FIG. 4, the GaAs contact layer 30 is removed by etching except for the current injection portion, and the p-side electrode 32 is formed through the insulating film 31 from which the portion to be the current injection portion is removed. An n-side electrode 33 is formed on the back surface of the substrate 21.

ここで、Ga1-xInxAs井戸層25a,25bのIn組成xは31%〜42%とした。また、各井戸層25a、25bの厚さは、In組成の増加に合わせて、約9nm〜約6nmと薄くしていった。これらのレーザの量子井戸層厚さは、Matthews and Blakesleeの理論に基づく臨界膜厚hよりも厚い条件となっている。例えば、In組成32%、厚さ8.6nmの場合、発振波長は1.13μmであり、また、In組成36%、厚さ7.8nmの場合、発振波長は1.16μmであり、また、 In組成39%、厚さ7.2nmの場合、発振波長は1.2μmであった。また、各井戸層25a,25bの圧縮歪み量は、組成に応じて変化し、約2.2%〜2.7%であった。 Here, the In composition x of the Ga 1-x In x As well layers 25a and 25b was 31% to 42%. The thickness of each well layer 25a, 25b was reduced to about 9 nm to about 6 nm in accordance with the increase in In composition. The quantum well layer thicknesses of these lasers has a thicker conditions than the critical film thickness h c based on the theory of Matthews and Blakeslee. For example, when the In composition is 32% and the thickness is 8.6 nm, the oscillation wavelength is 1.13 μm, and when the In composition is 36% and the thickness is 7.8 nm, the oscillation wavelength is 1.16 μm. When the In composition was 39% and the thickness was 7.2 nm, the oscillation wavelength was 1.2 μm. Moreover, the amount of compressive strain of each well layer 25a, 25b varied depending on the composition, and was about 2.2% to 2.7%.

図4の半導体発光素子の各層の成長方法はMOCVD法で行なった。その原料にはTMG(トリメチルガリウム),TMI(トリメチルインジウム),AsH3(アルシン),PH3(フォスフィン)を用い、キャリアガスにはH2を用いた。また、GaInAs層は550℃で成長した。 The growth method of each layer of the semiconductor light emitting device of FIG. 4 was performed by MOCVD. TMG (trimethylgallium), TMI (trimethylindium), AsH 3 (arsine), and PH 3 (phosphine) were used as the raw material, and H 2 was used as the carrier gas. The GaInAs layer was grown at 550 ° C.

図5には、図4の半導体発光素子の発振波長に対するしきい電流密度Jthが示されている。図5から、図4の半導体発光素子の発振波長は1.13〜1.23μmであり、従来のGaAs基板上に成長したGaInAs量子井戸レーザ素子に比べて発振波長が長波長化できていることがわかる。また、発振波長が1.2μmを越えると急激にしきい値が上昇するが、1.2μm程度までは、しきい電流密度Jthは200A/cm2程度であり,充分低いこともわかる。また、高温での特性も良好であった。 FIG. 5 shows the threshold current density J th with respect to the oscillation wavelength of the semiconductor light emitting device of FIG. From FIG. 5, the oscillation wavelength of the semiconductor light emitting device of FIG. 4 is 1.13 to 1.23 μm, and the oscillation wavelength can be made longer than that of a GaInAs quantum well laser device grown on a conventional GaAs substrate. I understand. In addition, when the oscillation wavelength exceeds 1.2 μm, the threshold value suddenly rises. However, until about 1.2 μm, the threshold current density J th is about 200 A / cm 2 and is sufficiently low. Also, the characteristics at high temperature were good.

なお、上述の例では、半導体発光素子の成長を、MOCVD法で行なったが、MBE法等、他の成長方法を用いることもできる。また、図4の半導体発光素子では、活性層(発光層)の積層構造として、二重量子井戸構造(DQW)の例を示したが、他の井戸数の量子井戸を用いた構造(SQW,MQW)を用いることもできる。また、各層の組成厚さ等は、必要に応じて、変更設定できる。また、クラッド層には、GaInP(As)と同様のワイドギャップのAlGaAsを用いることもできる。また、レーザの構造も他の構造にしても良い。ただし、GaAs基板の面方位については、(100)付近が良く、面方位の(100)からの傾き角度は5°の範囲内が好ましい。また、MOCVD法等で面方位(100)または少し傾いた(100)基板上にGaInPを成長するとヒロックと呼ばれる丘状欠陥が形成されやすい。これは素子の歩留り低下や発光効率低下などの悪影響を招き好ましくない。成長条件の最適化でヒロック密度を低減できるが、Asを含ませたGaInPAsとすることで容易に低減できる。As組成はわずかでも効果があり、好ましい。   In the above example, the semiconductor light emitting device is grown by the MOCVD method, but other growth methods such as the MBE method can also be used. In the semiconductor light emitting device of FIG. 4, an example of a double quantum well structure (DQW) is shown as the stacked structure of the active layer (light emitting layer), but a structure using quantum wells having other numbers of wells (SQW, MQW) can also be used. The composition thickness of each layer can be changed and set as necessary. Further, the wide gap AlGaAs similar to GaInP (As) can be used for the cladding layer. Also, the structure of the laser may be another structure. However, the surface orientation of the GaAs substrate is preferably in the vicinity of (100), and the inclination angle of the surface orientation from (100) is preferably within a range of 5 °. Further, when GaInP is grown on a (100) substrate having a plane orientation (100) or slightly inclined by MOCVD or the like, a hill-like defect called hillock is likely to be formed. This is undesirable because it adversely affects device yield and light emission efficiency. Although the hillock density can be reduced by optimizing the growth conditions, it can be easily reduced by using GaInPAs containing As. The As composition is preferable because it has a slight effect.

図6は実施例2の半導体発光素子を示す図である。ここでは、半導体発光素子として、最も簡単な構造である絶縁膜ストライプ型レーザを例にして説明する。図6の半導体発光素子は、層構造として、SCH−DQW(SeparateConfinement Heterostructure Double Quantum Well)構造を有している。具体的に、図6の半導体発光素子は、面方位(100)のn−GaAs基板41上に、n−GaAsバッファ層42と、n−GaInP(As)下部クラッド層43(膜厚が1.5μm)と、GaAs光ガイド層44(膜厚が100nm)と、Ga0.67In0.330.006As0.994井戸層45a,45bおよびGaAsバリア層46(膜厚が13nm)からなる活性層(発光層)47と、GaAs光ガイド層48(膜厚が100nm)と、p−GaInP(As)上部クラッド層49(膜厚が1.5μm)と、p−GaAsコンタクト層50(膜厚が0.3μm)とが、順次に形成されている。また、図6の半導体発光素子では、GaAsコンタクト層50は電流注入部分以外はエッチングにより除去され、電流注入部となる部分を除去した絶縁膜51を介してp側電極52が形成されている。また、基板41の裏面にはn側電極53が形成されている。 6 is a view showing a semiconductor light emitting device of Example 2. FIG. Here, an insulating film stripe type laser having the simplest structure will be described as an example of the semiconductor light emitting element. The semiconductor light emitting device of FIG. 6 has an SCH-DQW (Separate Confinement Heterostructure Double Quantum Well) structure as a layer structure. Specifically, the semiconductor light emitting device of FIG. 6 has an n-GaAs buffer layer 42 and an n-GaInP (As) lower cladding layer 43 (with a film thickness of 1.. 5 μm), a GaAs light guide layer 44 (film thickness is 100 nm), an active layer (light emitting layer) 47 comprising Ga 0.67 In 0.33 N 0.006 As 0.994 well layers 45a and 45b and a GaAs barrier layer 46 (film thickness is 13 nm). GaAs light guide layer 48 (film thickness is 100 nm), p-GaInP (As) upper cladding layer 49 (film thickness is 1.5 μm), p-GaAs contact layer 50 (film thickness is 0.3 μm), Are sequentially formed. In the semiconductor light emitting device of FIG. 6, the GaAs contact layer 50 is removed by etching except for the current injection portion, and the p-side electrode 52 is formed through the insulating film 51 from which the portion to be the current injection portion is removed. An n-side electrode 53 is formed on the back surface of the substrate 41.

ここで、各井戸層45a,45bのIn組成xは33%、窒素(N)組成は0.6%とした。また、各井戸層45a,45bの厚さは7nmとした。また、各井戸層45a,45bの圧縮歪み量は約2.3%であった。   Here, the In composition x of each well layer 45a, 45b was 33%, and the nitrogen (N) composition was 0.6%. The thickness of each well layer 45a, 45b was 7 nm. Further, the amount of compressive strain of each of the well layers 45a and 45b was about 2.3%.

図6の半導体発光素子の各層の成長方法はMOCVD法で行なった。その原料にはTMG(トリメチルガリウム),TMI(トリメチルインジウム),AsH3(アルシン),PH3(フォスフィン)を用い、そして窒素の原料にはDMHy(ジメチルヒドラジン)を用いた。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いる。また、特に、歪みの大きい量子井戸層を成長する場合は例えば500℃〜600℃程度の低温成長が好ましい。すなわち、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。いまの例では、GaInNAs井戸層45a,45bは550℃で成長した。また、キャリアガスにはH2を用いた。 The growth method of each layer of the semiconductor light emitting device of FIG. 6 was performed by MOCVD. TMG (trimethylgallium), TMI (trimethylindium), AsH 3 (arsine), and PH 3 (phosphine) were used as the raw material, and DMHy (dimethylhydrazine) was used as the nitrogen raw material. DMHy decomposes at low temperatures and is therefore suitable for low temperature growth at 600 ° C. or lower. In particular, when a quantum well layer having a large strain is grown, a low temperature growth of, for example, about 500 ° C. to 600 ° C. is preferable. That is, since DMHy decomposes at a low temperature, it is suitable for a low temperature growth of 600 ° C. or lower, and is particularly preferable when a quantum well layer having a large strain required for low temperature growth is grown. In the present example, the GaInNAs well layers 45a and 45b were grown at 550 ° C. Further, H 2 was used as a carrier gas.

図7には、図6の半導体発光素子の連続動作での電流−出力パワー(電圧)特性が示されている。ここで、しきい電流密度Jthは570A/cm2であった。また、発振波長は約1.24μmであった。図6の半導体発光素子では、井戸層45a,45bのIn組成を30%より大きくし、圧縮歪み量を2%以上にしたことにより、従来のGaInNAsレーザ素子に比べて、しきい電流密度Jthを劇的に低減できた。また、高温での特性も良好であった。また、発振波長は、窒素組成,In組成,および井戸層の厚さ等の制御で可変である。 FIG. 7 shows current-output power (voltage) characteristics in the continuous operation of the semiconductor light emitting device of FIG. Here, the threshold current density J th was 570 A / cm 2 . The oscillation wavelength was about 1.24 μm. In the semiconductor light emitting device of FIG. 6, the threshold current density J th is higher than that of the conventional GaInNAs laser device by making the In composition of the well layers 45a and 45b larger than 30% and the compressive strain amount being 2% or more. Was dramatically reduced. Also, the characteristics at high temperature were good. The oscillation wavelength is variable by controlling the nitrogen composition, the In composition, the thickness of the well layer, and the like.

なお、上述の例では、半導体発光素子の成長を、MOCVD法で行なったが、MBE法等他の成長方法を用いることもできる。また、図6の半導体発光素子では、井戸層45a,45bの窒素(N)の原料に、DMHyを用いたが、活性化した窒素やNH3等他の窒素化合物を用いることもできる。また、図6の半導体発光素子では、活性層(発光層)の積層構造として2重量子井戸構造(DQW)の例を示したが、他の井戸数の量子井戸を用いた構造(SQW,MQW)を用いることもできる。また、各層の組成厚さ等は、必要に応じて、変更設定できる。また、クラッド層には、GaInP(As)と同様のワイドギャップのAlGaAsを用いることもできる。また、レーザの構造も他の構造にしても良い。 In the above example, the semiconductor light emitting device is grown by MOCVD, but other growth methods such as MBE can be used. In the semiconductor light emitting device of FIG. 6, DMHy is used as the material for nitrogen (N) in the well layers 45a and 45b, but other nitrogen compounds such as activated nitrogen and NH 3 can also be used. In the semiconductor light emitting device of FIG. 6, an example of a double quantum well structure (DQW) is shown as a stacked structure of active layers (light emitting layers), but a structure using quantum wells having other numbers of wells (SQW, MQW). ) Can also be used. The composition thickness of each layer can be changed and set as necessary. Further, the wide gap AlGaAs similar to GaInP (As) can be used for the cladding layer. Also, the structure of the laser may be another structure.

図8は実施例3の半導体発光素子を示す図である。ここでは、半導体発光素子として、最も簡単な構造である絶縁膜ストライプ型レーザを例にして説明する。図8の半導体発光素子は、層構造として、SCH−DQW(SeparateConfinement Heterostructure Double Quantum Well)構造を有している。実施例3の図8の半導体発光素子は、実施例2の図6とほぼ同様の構造となっているが、n−GaAs基板41の面方位が(100)から[011]方向に2°の角度で傾いたものとなっている。また、井戸層の組成等が実施例2と相違している。   FIG. 8 is a view showing a semiconductor light emitting device of Example 3. Here, an insulating film stripe type laser having the simplest structure will be described as an example of the semiconductor light emitting element. The semiconductor light emitting device of FIG. 8 has an SCH-DQW (Separate Confinement Heterostructure Double Quantum Well) structure as a layer structure. The semiconductor light emitting device of FIG. 8 of Example 3 has substantially the same structure as that of FIG. 6 of Example 2, but the plane orientation of the n-GaAs substrate 41 is 2 ° from the (100) to the [011] direction. It is tilted at an angle. Further, the composition of the well layer is different from that of Example 2.

すなわち、図8の半導体発光素子は、面方位が(100)から[011]方向に2°の角度で傾いたn−GaAs基板61上に、n−GaAsバッファ層62と、n−GaInP(As)下部クラッド層63(膜厚が1.5μm)と、GaAs光ガイド層64(膜厚が100nm)と、Ga0.6In0.40.005As0.995井戸層65a,65bおよびGaAsバリア層66(膜厚が13nm)からなる活性層(発光層)67と、GaAs光ガイド層68(膜厚が100nm)と、p−GaInP(As)上部クラッド層69(膜厚が1.5μm)と、p−GaAsコンタクト層70(膜厚が0.3μm)とが、順次に形成されている。また、図8の半導体発光素子では、GaAsコンタクト層70は電流注入部分以外はエッチングにより除去され、電流注入部となる部分を除去した絶縁膜71を介してp側電極72が形成されている。また、基板61の裏面にはn側電極73が形成されている。 That is, the semiconductor light emitting device of FIG. 8 has an n-GaAs buffer layer 62 and an n-GaInP (As) on an n-GaAs substrate 61 whose plane orientation is inclined at an angle of 2 ° from the (100) direction to the [011] direction. ) Lower cladding layer 63 (film thickness is 1.5 μm), GaAs light guide layer 64 (film thickness is 100 nm), Ga 0.6 In 0.4 N 0.005 As 0.995 well layers 65a and 65b, and GaAs barrier layer 66 (film thickness is 13 nm) active layer (light emitting layer) 67, GaAs light guide layer 68 (film thickness is 100 nm), p-GaInP (As) upper clad layer 69 (film thickness is 1.5 μm), p-GaAs contact Layers 70 (film thickness is 0.3 μm) are sequentially formed. Further, in the semiconductor light emitting device of FIG. 8, the GaAs contact layer 70 is removed by etching except for the current injection portion, and the p-side electrode 72 is formed via the insulating film 71 from which the portion to be the current injection portion is removed. An n-side electrode 73 is formed on the back surface of the substrate 61.

ここで、各井戸層65a,65bのIn組成xは40%,窒素(N)組成は0.5%とした。また、各井戸層65a,65bの厚さは7nmとした。これはMatthews and Blakesleeの理論に基づく臨界膜厚hc(約6.1nm)よりも厚い条件となっている。また、各井戸層65a,65bの圧縮歪み量は約2.7%であった。 Here, the In composition x of each well layer 65a, 65b was 40%, and the nitrogen (N) composition was 0.5%. The thickness of each well layer 65a, 65b was 7 nm. This is a condition thicker than the critical film thickness h c (about 6.1 nm) based on the theory of Matthews and Blakeslee. Further, the amount of compressive strain of each of the well layers 65a and 65b was about 2.7%.

図8の半導体発光素子の各層の成長方法はMOCVD法で行なった。その原料にはTMG(トリメチガリウム),TMI(トリメチルインジウム),AsH3(アルシン),PH3(フォスフィン)を用い、そして窒素の原料にはDMHy(ジメチルヒドラジン)を用いた。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いる。また、特に、歪みの大きい量子井戸層を成長する場合は、例えば500℃〜600℃程度の低温成長が好ましい。いまの例では、GaInNAs井戸層65a,65bは540℃で成長した。また、キャリアガスにはH2を用いた。 The growth method of each layer of the semiconductor light emitting device of FIG. 8 was performed by MOCVD. TMG (trimethylgallium), TMI (trimethylindium), AsH 3 (arsine), and PH 3 (phosphine) were used as the raw material, and DMHy (dimethylhydrazine) was used as the nitrogen raw material. DMHy decomposes at low temperatures and is therefore suitable for low temperature growth at 600 ° C. or lower. In particular, when a quantum well layer having a large strain is grown, a low temperature growth of about 500 ° C. to 600 ° C. is preferable, for example. In the present example, the GaInNAs well layers 65a and 65b were grown at 540 ° C. Further, H 2 was used as a carrier gas.

このように作製した図8の半導体発光素子の発振波長は約1.3μmであった。また、しきい電流密度Jthは1kA/cm2以下であった。GaInNAsレーザは,窒素組成が大きくなるほどしきい電流密度が大きくなる傾向がある。従来の1.3μm帯のGaInNAsレーザ素子においては窒素組成は小さくしても1%(In組成が30%の時)であったが、本発明では、In組成を30%より大きくし、圧縮歪み量を2%以上にしたことにより、従来より窒素組成を小さくでき、しきい電流密度を劇的に低減できた。また、高温での特性も良好であった。 The oscillation wavelength of the semiconductor light emitting device of FIG. 8 produced in this way was about 1.3 μm. The threshold current density J th was 1 kA / cm 2 or less. In GaInNAs lasers, the threshold current density tends to increase as the nitrogen composition increases. In the conventional 1.3 μm GaInNAs laser element, the nitrogen composition was 1% at the minimum (when the In composition was 30%). However, in the present invention, the In composition is made larger than 30% to compress the strain. By making the amount 2% or more, the nitrogen composition can be made smaller than before, and the threshold current density can be dramatically reduced. Also, the characteristics at high temperature were good.

なお、上述の例では、半導体発光素子の成長を、MOCVD法で行なったが、MBE法等他の成長方法を用いることもできる。また、図8の半導体発光素子では、井戸層65a,65bの窒素(N)の原料に、DMHyを用いたが、活性化した窒素やNH3等他の窒素化合物を用いることもできる。また、図8の半導体発光素子では、活性層(発光層)の積層構造として2重量子井戸構造(DQW)の例を示したが、他の井戸数の量子井戸を用いた構造(SQW,MQW)を用いることもできる。また、各層の組成厚さ等は、必要に応じて、変更設定できる。また、クラッド層には、GaInP(As)と同様のワイドギャップのAlGaAsを用いることもできる。また、レーザの構造も他の構造にしても良い。 In the above example, the semiconductor light emitting device is grown by MOCVD, but other growth methods such as MBE can be used. In the semiconductor light emitting device of FIG. 8, DMHy is used as the nitrogen (N) material of the well layers 65a and 65b, but other nitrogen compounds such as activated nitrogen and NH 3 can also be used. In the semiconductor light emitting device of FIG. 8, the example of the double quantum well structure (DQW) is shown as the stacked structure of the active layer (light emitting layer), but the structure using the quantum wells having other numbers of wells (SQW, MQW). ) Can also be used. The composition thickness of each layer can be changed and set as necessary. Further, the wide gap AlGaAs similar to GaInP (As) can be used for the cladding layer. Also, the structure of the laser may be another structure.

図9は実施例4の半導体発光素子を示す図である。ここでは、半導体発光素子として、最も簡単な構造である絶縁膜ストライプ型レーザを例にして説明する。図9の半導体発光素子は、層構造として、SCH−DQW(SeparateConfinement Heterostructure Double Quantum Well)構造を有している。具体的に、図9の半導体発光素子は、面方位が(100)から[011]方向に5°の角度で傾いたn−GaAs基板81上に、n−GaAsバッファ層82と、n−GaInP(As)下部クラッド層83(膜厚が1.5μm)と、GaAs光ガイド層84(膜厚が100nm)と、Ga0.65In0.350.007As0.993井戸層85a,85bと井戸層85a,85bの間および井戸層85aの下方および井戸層85bの上方に設けられたGaNPAsバリア層86a,86b,86c(各膜厚が10nm)とが形成されている活性層(発光層)87と、GaAs光ガイド層88(膜厚が100nm)と、p−GaInP(As)上部クラッド層89(膜厚が1.5μm)と、p−GaAsコンタクト層90(膜厚が0.3μm)とが順次に形成されている。また、図9の半導体発光素子では、GaAsコンタクト層90は電流注入部分以外はエッチングにより除去され、電流注入部となる部分を除去した絶縁膜91を介してp側電極92が形成されている。また、基板91の裏面にはn側電極93が形成されている。 FIG. 9 is a diagram showing a semiconductor light emitting device of Example 4. Here, an insulating film stripe type laser having the simplest structure will be described as an example of the semiconductor light emitting element. The semiconductor light emitting device of FIG. 9 has a SCH-DQW (Separate Confinement Heterostructure Double Quantum Well) structure as a layer structure. Specifically, the semiconductor light emitting device of FIG. 9 has an n-GaAs buffer layer 82, an n-GaInP on an n-GaAs substrate 81 whose plane orientation is inclined at an angle of 5 ° from the (100) direction to the [011] direction. (As) The lower cladding layer 83 (thickness is 1.5 μm), the GaAs light guide layer 84 (thickness is 100 nm), Ga 0.65 In 0.35 N 0.007 As 0.993 well layers 85a and 85b, and well layers 85a and 85b. An active layer (light emitting layer) 87 formed with GaNPAs barrier layers 86a, 86b, 86c (each film thickness is 10 nm) provided between and below the well layer 85a and above the well layer 85b, and a GaAs light guide A layer 88 (with a film thickness of 100 nm), a p-GaInP (As) upper cladding layer 89 (with a film thickness of 1.5 μm), and a p-GaAs contact layer 90 (with a film thickness of 0.3 μm) are sequentially formed. ing. Further, in the semiconductor light emitting device of FIG. 9, the GaAs contact layer 90 is removed by etching except for the current injection portion, and the p-side electrode 92 is formed through the insulating film 91 from which the portion to be the current injection portion is removed. An n-side electrode 93 is formed on the back surface of the substrate 91.

ここで、各井戸層85a,85bのIn組成xは35%,窒素(N)組成は0.7%とした。また、各井戸層85a,85bの厚さは7nmとした。また、各井戸層85a,85bの圧縮歪み量は約2.4%であった。この際、バリア層86a,86b,86cは引っ張り歪を有しており、井戸層85a,85bの圧縮みを緩和している。   Here, the In composition x of each of the well layers 85a and 85b was 35%, and the nitrogen (N) composition was 0.7%. The thickness of each well layer 85a, 85b was 7 nm. The compressive strain amount of each well layer 85a and 85b was about 2.4%. At this time, the barrier layers 86a, 86b, 86c have tensile strain, and alleviate the compression of the well layers 85a, 85b.

図9の半導体発光素子の各層の成長方法はMOCVD法で行なった。その原料にはTMG(トリメチガリウム),TMI(トリメチルインジウム),AsH3(アルシン),PH3(フォスフィン)を用い、そして窒素の原料にはDMHy(ジメチルヒドラジン)を用いた。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いる。また、特に、歪みの大きい量子井戸層を成長する場合は、例えば500℃〜600℃程度の低温成長が好ましい。いまの例では、GaInNAs層は520℃で成長した。また、キャリアガスにはH2を用いた。 The growth method of each layer of the semiconductor light emitting device of FIG. 9 was performed by MOCVD. TMG (trimethylgallium), TMI (trimethylindium), AsH 3 (arsine), and PH 3 (phosphine) were used as the raw material, and DMHy (dimethylhydrazine) was used as the nitrogen raw material. DMHy decomposes at low temperatures and is therefore suitable for low temperature growth at 600 ° C. or lower. In particular, when a quantum well layer having a large strain is grown, a low temperature growth of about 500 ° C. to 600 ° C. is preferable, for example. In the present example, the GaInNAs layer was grown at 520 ° C. Further, H 2 was used as a carrier gas.

このように作製した図9の半導体発光素子の発振波長は約1.3μmであった。また、しきい電流密度Jthは1kA/cm2以下であった。GaInNAsレーザは,窒素組成が大きくなるほどしきい電流密度が大きくなる傾向がある。従来の1.3μm帯のGaInAsレーザ素子においては窒素組成は小さくしても1%(In組成が30%の時)であったが、本発明では、In組成を30%より大きくし、圧縮歪み量を2%以上にしたことにより、従来より窒素組成を小さくでき、しきい電流密度を劇的に低減できた。さらに、実施例4では、井戸層85a,85bの圧縮歪みを緩和する引っ張り歪みを有するバリア層86b,86cがさらに設けられているので、実施例3の素子よりもしきい電流密度は低減した。また、高温での特性も良好であった。 The oscillation wavelength of the semiconductor light emitting device of FIG. 9 manufactured in this way was about 1.3 μm. The threshold current density J th was 1 kA / cm 2 or less. In GaInNAs lasers, the threshold current density tends to increase as the nitrogen composition increases. In a conventional 1.3 μm band GaInAs laser element, the nitrogen composition was 1% at the minimum (when the In composition was 30%). However, in the present invention, the In composition is made larger than 30% and the compressive strain is increased. By making the amount 2% or more, the nitrogen composition can be made smaller than before, and the threshold current density can be dramatically reduced. Furthermore, in Example 4, since the barrier layers 86b and 86c having tensile strain that relieve the compressive strain of the well layers 85a and 85b are further provided, the threshold current density is reduced as compared with the element of Example 3. Also, the characteristics at high temperature were good.

なお、上述の例では、半導体発光素子の成長を、MOCVD法で行なったが、MBE法等他の成長方法を用いることもできる。また、図9の半導体発光素子では、井戸層85a,85bの窒素(N)の原料に、DMHyを用いたが、活性化した窒素やNH3等他の窒素化合物を用いることもできる。また、図9の半導体発光素子では、活性層(発光層)の積層構造として2重量子井戸構造(DQW)の例を示したが、他の井戸数の量子井戸を用いた構造(SQW,MQW)を用いることもできる。また、各層の組成厚さ等は、必要に応じて、変更設定できる。また、クラッド層には、GaInP(As)と同様のワイドギャップのAlGaAsを用いることもできる。また、レーザの構造も他の構造にしても良い。 In the above example, the semiconductor light emitting device is grown by MOCVD, but other growth methods such as MBE can be used. In the semiconductor light emitting device of FIG. 9, DMHy is used as the nitrogen (N) material for the well layers 85a and 85b, but other nitrogen compounds such as activated nitrogen and NH 3 can also be used. In the semiconductor light emitting device of FIG. 9, an example of a double quantum well structure (DQW) is shown as a stacked structure of active layers (light emitting layers), but a structure using quantum wells with other numbers of wells (SQW, MQW). ) Can also be used. The composition thickness of each layer can be changed and set as necessary. Further, the wide gap AlGaAs similar to GaInP (As) can be used for the cladding layer. Also, the structure of the laser may be another structure.

図10は実施例5の半導体発光素子(半導体レーザ)を示す図である。図10に示す半導体発光素子は面発光型である。この半導体発光素子は、発光を得るための共振器を構成するため、量子井戸活性層104の半導体基板101とは反対の側には上部反射鏡109が形成され、また、量子井戸活性層104の半導体基板101側には下部反射鏡102が形成されており、上部反射鏡109と下部反射鏡102のうちの少なくとも下部反射鏡102は、Alを含まない材料による低屈折率層と高屈折率層とが交互に積層された半導体多層膜として構成されている。この構成では、上部反射鏡109,下部反射鏡102は、量子井戸活性層104からの発光に対する共振器として機能するようになっている。   FIG. 10 is a diagram showing a semiconductor light emitting device (semiconductor laser) of Example 5. The semiconductor light emitting element shown in FIG. 10 is a surface emitting type. Since this semiconductor light emitting device constitutes a resonator for obtaining light emission, an upper reflecting mirror 109 is formed on the opposite side of the quantum well active layer 104 to the semiconductor substrate 101, and the quantum well active layer 104 A lower reflecting mirror 102 is formed on the semiconductor substrate 101 side, and at least the lower reflecting mirror 102 of the upper reflecting mirror 109 and the lower reflecting mirror 102 is composed of a low refractive index layer and a high refractive index layer made of a material not containing Al. Are configured as a semiconductor multilayer film alternately stacked. In this configuration, the upper reflecting mirror 109 and the lower reflecting mirror 102 function as resonators for light emission from the quantum well active layer 104.

より具体的に、図10の半導体発光素子は、面方位(100)のn−GaAs基板101上に、GaAs基板101に格子整合するn−Ga0.5In0.5Pとn−GaAs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(35周期)からなるn−半導体多層膜反射鏡(GaInP/GaAs下部半導体多層膜反射鏡)102,GaAsスペーサ層103,3層のGa0.6In0.40.005As0.995As井戸層とGaAsバリア層(13nm)からなる多重量子井戸活性層(GaInNAs/GaAs QW活性層)104,GaAsスペーサ層105,Alxy電流狭さく層106,電流注入部としてのp−AlAs層107(膜厚が50nm),p−GaAsコンタクト層108,GaAs基板101に格子整合するp−Ga0.5In0.5Pとp−GaAs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(30周期)からなるp−半導体多層膜反射鏡(GaInP/GaAs上部半導体多層膜反射鏡)109が順次に成長されている。 More specifically, the semiconductor light emitting device of FIG. 10 includes n-Ga 0.5 In 0.5 P and n-GaAs lattice-matched to the GaAs substrate 101 on the n-GaAs substrate 101 having the plane orientation (100) in each medium. N-semiconductor multilayer mirror (GaInP / GaAs lower semiconductor multilayer mirror) 102, GaAs spacer layers 103, 3 having a periodic structure (35 periods) stacked alternately with a thickness of 1/4 of the oscillation wavelength in FIG. Multi-quantum well active layer (GaInNAs / GaAs QW active layer) 104 consisting of Ga 0.6 In 0.4 N 0.005 As 0.995 As well layer and GaAs barrier layer (13 nm), GaAs spacer layer 105, Al x O y current narrowing layer 106 , P-AlAs layer 107 (film thickness is 50 nm) as a current injection part, p-GaAs contact layer 108, and p-Ga lattice matched to GaAs substrate 101 P-semiconductor multilayer reflector (GaInP / GaAs upper semiconductor) having a periodic structure (30 periods) in which 0.5 In 0.5 P and p-GaAs are alternately stacked with a thickness of 1/4 times the oscillation wavelength in each medium. A multilayer reflector 109) is sequentially grown.

また、GaAsスペ−サ層103,量子井戸活性層104,GaAsスペ−サ層105,電流狭さく層106,p−GaAsコンタクト層108の側面には、絶縁膜(ポリイミド)110が形成され、また、p−GaAsコンタクト層108上にはp側電極111が形成され、また、GaAs基板101の裏面にはn側電極112が形成されている。   An insulating film (polyimide) 110 is formed on the side surfaces of the GaAs spacer layer 103, the quantum well active layer 104, the GaAs spacer layer 105, the current narrowing layer 106, and the p-GaAs contact layer 108. A p-side electrode 111 is formed on the p-GaAs contact layer 108, and an n-side electrode 112 is formed on the back surface of the GaAs substrate 101.

図10の半導体発光素子を次のように作製した。すなわち、先ず、面方位(100)のn−GaAs基板101上に、GaAs基板101に格子整合するn−Ga0.5In0.5Pとn−GaAs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(35周期)からなるn−半導体多層膜反射鏡(GaInP/GaAs下部半導体多層膜反射鏡)102,GaAsスペーサ層103,3層のGa0.6In0.40.005As0.995As井戸層とGaAsバリア層(13nm)からなる多重量子井戸活性層(GaInNAs/GaAs QW活性層)104,GaAsスペーサ層105,Alxy電流狭さく層106,電流注入部としてのp−AlAs層107(膜厚が50nm),p−GaAsコンタクト層108,GaAs基板101に格子整合するp−Ga0.5In0.5Pとp−GaAs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(30周期)からなるp−半導体多層膜反射鏡(GaInP/GaAs上部半導体多層膜反射鏡)109を順次成長させた。 The semiconductor light emitting device of FIG. 10 was produced as follows. That is, first, n-Ga 0.5 In 0.5 P and n-GaAs lattice-matched to the GaAs substrate 101 on the n-GaAs substrate 101 having the plane orientation (100) are ¼ times the oscillation wavelength in each medium. N-semiconductor multilayer reflector (GaInP / GaAs lower semiconductor multilayer reflector) 102 having a periodic structure (35 periods) stacked alternately by thickness, GaAs spacer layer 103, and three layers of Ga 0.6 In 0.4 N 0.005 As 0.995 Multiple quantum well active layer (GaInNAs / GaAs QW active layer) 104 composed of an As well layer and a GaAs barrier layer (13 nm), a GaAs spacer layer 105, an Al x O y current narrowing layer 106, and p-AlAs as a current injection portion layer 107 (film thickness 50 nm), lattice-matched to the p-GaAs contact layer 108, GaAs substrate 101 p-Ga 0.5 in 0.5 P and p-Ga A p-semiconductor multilayer mirror (GaInP / GaAs upper semiconductor multilayer mirror) 109 having a periodic structure (30 periods) in which s are alternately stacked with a thickness of 1/4 times the oscillation wavelength in each medium is provided. Grown sequentially.

ここで、井戸層のIn組成xは40%,窒素組成は0.5%とした。また、井戸層の厚さは7nmとした。これはMatthews and Blakesleeの理論に基づく臨界膜厚hc(約6.1nm)よりも厚い条件となっている。また、圧縮歪量は約2.7%であった。成長方法はMOCVD法で行なった。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),AsH3(アルシン),PH3(フォスフィン),そして窒素の原料にはDMHy(ジメチルヒドラジン)を用いた。 Here, the In composition x of the well layer was 40%, and the nitrogen composition was 0.5%. The thickness of the well layer was 7 nm. This is a condition thicker than the critical film thickness h c (about 6.1 nm) based on the theory of Matthews and Blakeslee. The amount of compressive strain was about 2.7%. The growth method was the MOCVD method. TMG (trimethylgallium), TMI (trimethylindium), AsH 3 (arsine), PH 3 (phosphine) were used as raw materials, and DMHy (dimethylhydrazine) was used as a raw material for nitrogen.

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いる。また、歪みの大きい量子井戸層を成長する場合は例えば500℃〜600℃程度の低温成長が好ましい。この実施例5では、GaInNAs層は540℃で成長した。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には好ましい。また、キャリアガスにはH2を用いた。 Since DMHy decomposes at low temperatures, it is suitable for low-temperature growth at 600 ° C. or lower. Moreover, when growing a quantum well layer with a large strain, a low temperature growth of about 500 ° C. to 600 ° C. is preferable, for example. In Example 5, the GaInNAs layer was grown at 540 ° C. Since DMHy decomposes at low temperatures, it is suitable for low temperature growth such as 600 ° C. or lower, and is particularly preferable when growing a quantum well layer having a large strain required for low temperature growth. Further, H 2 was used as a carrier gas.

そして、フォトリソグラフィ−とエッチング工程により下部多層膜反射鏡102の上部まで直径30μmの円形にメサエッチングし、更に上部多層膜反射鏡109のみを直径10μmの円形にメサエッチングした。Alxy電流狭さく部106は側面の現れたAlAsを水蒸気で側面から酸化して形成した。 Then, mesa etching was performed in a circular shape having a diameter of 30 μm up to the upper portion of the lower multilayer film reflecting mirror 102 by photolithography and an etching process, and only the upper multilayer film reflecting mirror 109 was mesa etched in a circular shape having a diameter of 10 μm. The Al x O y current narrowing portion 106 was formed by oxidizing AlAs appearing on the side surface from the side surface with water vapor.

次に、絶縁膜(ポリイミド)110でエッチング部を埋め込んで平坦化し、p側電極111が形成されるべき部分と光取り出し口となる上部多層膜反射鏡109上のポリイミドを除去し、p−GaAsコンタクト層108上にp側電極111を形成し、基板101の裏面にはn側電極112を形成した。   Next, the etched portion is filled with an insulating film (polyimide) 110 and planarized, and the portion on which the p-side electrode 111 is to be formed and the polyimide on the upper multilayer mirror 109 serving as the light extraction port are removed, and p-GaAs is removed. A p-side electrode 111 was formed on the contact layer 108, and an n-side electrode 112 was formed on the back surface of the substrate 101.

図10の半導体発光素子では、半導体基板101と活性層104との間のn−半導体多層膜反射鏡(下部半導体多層膜反射鏡)102として、Alを含まないn−GaInPとn−GaAsを用いたので、大きな歪みを有する活性層104を劣化させずに容易に成長できた。   In the semiconductor light emitting device of FIG. 10, n-GaInP and n-GaAs not containing Al are used as the n-semiconductor multilayer reflector (lower semiconductor multilayer reflector) 102 between the semiconductor substrate 101 and the active layer 104. Therefore, the active layer 104 having a large strain could be easily grown without deteriorating.

なお、半導体基板101と活性層104との間の下部半導体多層膜反射鏡102としては、Alを含まず、屈折率の大きい材料と小さい材料の組み合せを用いることができる。具体的に、GaInP(低屈折率層)とGaAs(高屈折率層)の組み合せの他、GaInPAs(低屈折率層)とGaAs(高屈折率層),GaInP(低屈折率層)とGaInPAs(高屈折率層),GaInP(低屈折率層)とGaPAs(高屈折率層),GaInP(低屈折率層)とGaInAs(高屈折率層),GaInP(低屈折率層)とGaInNAs(高屈折率層)等の組み合せを用いることができる。もちろん、下部半導体多層膜反射鏡の材料としてAlを含まない材料を用いた方が、その上に大きな歪みを有する活性層を成長することが容易であるが、Alを含んだ材料を用いても成長条件を適正化することで用いることはできる。具体的に、AlAs(低屈折率層)とGaAs(高屈折率層)の組み合せ,AlGaAsとGaAs,AlAsとAlGaAs,AlGaAs(Al組成が大きい)とAlGaAs(Al組成が小さい)等の組み合せを用いることができる。   The lower semiconductor multilayer mirror 102 between the semiconductor substrate 101 and the active layer 104 does not contain Al, and a combination of a material having a large refractive index and a material having a small refractive index can be used. Specifically, in addition to the combination of GaInP (low refractive index layer) and GaAs (high refractive index layer), GaInPAs (low refractive index layer) and GaAs (high refractive index layer), GaInP (low refractive index layer) and GaInPAs ( High refractive index layer), GaInP (low refractive index layer) and GaPAs (high refractive index layer), GaInP (low refractive index layer) and GaInAs (high refractive index layer), GaInP (low refractive index layer) and GaInNAs (high refractive index) A combination such as a rate layer can be used. Of course, it is easier to grow an active layer having a large strain on the lower semiconductor multilayer film reflecting material using a material that does not contain Al, but even if a material containing Al is used. It can be used by optimizing the growth conditions. Specifically, a combination of AlAs (low refractive index layer) and GaAs (high refractive index layer), a combination of AlGaAs and GaAs, AlAs and AlGaAs, AlGaAs (large Al composition) and AlGaAs (low Al composition), etc. are used. be able to.

また、活性層104より表面側の上部半導体多層膜反射鏡109(この実施例ではp−半導体多層膜反射鏡)にも、Alを含まず、屈折率の大きい材料と小さい材料の組み合せを用いることができる。具体的に、GaInP(低屈折率層)とGaAs(高屈折率層)の組み合せの他、GaInPAs(低屈折率層)とGaAs(高屈折率層),GaInP(低屈折率層)とGaInPAs(高屈折率層),GaInP(低屈折率層)とGaPAs(高屈折率層),GaInP(低屈折率層)とGaInAs(高屈折率層),GaInP(低屈折率層)とGaInNAs(高屈折率層)等の組み合せを用いることができる。   Also, the upper semiconductor multilayer reflector 109 on the surface side of the active layer 104 (p-semiconductor multilayer reflector in this embodiment) does not contain Al and uses a combination of a material having a high refractive index and a material having a small refractive index. Can do. Specifically, in addition to the combination of GaInP (low refractive index layer) and GaAs (high refractive index layer), GaInPAs (low refractive index layer) and GaAs (high refractive index layer), GaInP (low refractive index layer) and GaInPAs ( High refractive index layer), GaInP (low refractive index layer) and GaPAs (high refractive index layer), GaInP (low refractive index layer) and GaInAs (high refractive index layer), GaInP (low refractive index layer) and GaInNAs (high refractive index) A combination such as a rate layer can be used.

但し、活性層104より表面側の上部半導体多層膜反射鏡109(この実施例ではp−半導体多層膜反射鏡)としてはAlを含んでいてもかまわない。具体的に、AlAs(低屈折率層)とGaAs(高屈折率層)の組み合せ,AlGaAsとGaAs,AlAsとAlGaAs,AlGaAs(Al組成が大きい)とAlGaAs(Al組成が小さい)等の組み合せを用いることができる。この場合、大きな歪み有する活性層104は、低温で成長されることから、できるだけ低温(例えば700℃以下)で成長することが好ましい。また、上部半導体多層膜反射鏡109としては誘電体多層膜を用いることもできる。具体的には、TiO2とSiO2の組み合せ等を用いることができる。 However, the upper semiconductor multilayer reflector 109 (p-semiconductor multilayer reflector in this embodiment) on the surface side of the active layer 104 may contain Al. Specifically, a combination of AlAs (low refractive index layer) and GaAs (high refractive index layer), a combination of AlGaAs and GaAs, AlAs and AlGaAs, AlGaAs (large Al composition) and AlGaAs (low Al composition), etc. are used. be able to. In this case, since the active layer 104 having a large strain is grown at a low temperature, the active layer 104 is preferably grown at a temperature as low as possible (for example, 700 ° C. or lower). In addition, a dielectric multilayer film can be used as the upper semiconductor multilayer film reflecting mirror 109. Specifically, a combination of TiO 2 and SiO 2 can be used.

このように作製した面発光レーザ(図10の半導体レ−ザ)の発振波長は約1.3μmであった。また、しきい電流密度は1kA/cm2以下であった。In組成を30%より大きくし、圧縮歪み量を2%以上にしたことにより、従来より窒素組成を小さくでき、しきい電流密度を劇的に低減できた。高温での特性も良好であった。また長寿命であった。 The surface emitting laser (semiconductor laser shown in FIG. 10) produced in this way had an oscillation wavelength of about 1.3 μm. The threshold current density was 1 kA / cm 2 or less. By making the In composition larger than 30% and the compressive strain amount being 2% or more, the nitrogen composition can be made smaller than before, and the threshold current density can be dramatically reduced. The characteristics at high temperature were also good. It also had a long life.

この実施例5では、MOCVD法での成長の例を示したが、MBE法等他の成長方法を用いることもできる。また、窒素の原料にDMHyを用いたが、活性化した窒素やNH3等他の窒素化合物を用いることもできる。 In the fifth embodiment, an example of the growth by the MOCVD method is shown, but other growth methods such as the MBE method can also be used. Further, although DMHy is used as a nitrogen raw material, other nitrogen compounds such as activated nitrogen and NH 3 can also be used.

また、上述の例では、積層構造として3重量子井戸構造(TQW)の例を示したが、他の井戸数の量子井戸を用いた構造(SQW,MQW)等を用いることもできる。また各層の組成厚さ等は必要に応じて他の値を設定できる。また、活性層104にはGaInAsを用いることもできる。レーザの構造も他の構造にしてもかまわない。   In the above example, an example of a triple quantum well structure (TQW) is shown as a stacked structure, but a structure using quantum wells with other numbers of wells (SQW, MQW) or the like can also be used. Further, the composition thickness of each layer can be set to other values as required. Further, GaInAs can be used for the active layer 104. The structure of the laser may be another structure.

図11は実施例6の半導体発光素子(半導体レーザ)を示す図である。図11に示す半導体発光素子は面発光型である。この半導体発光素子は、発光を得るための共振器を構成するため、量子井戸活性層123の半導体基板121とは反対の側には上部反射鏡128が形成され、また、量子井戸活性層123の半導体基板121側には下部反射鏡129が形成されており、上部反射鏡128と下部反射鏡129のうちの少なくとも下部反射鏡129は、誘電体材料による低屈折率層と高屈折率層とが交互に積層された誘電体多層膜として構成されている。この構成においても、上部反射鏡128,下部反射鏡129は、量子井戸活性層123からの発光に対する共振器として機能するようになっている。   FIG. 11 is a diagram showing a semiconductor light emitting device (semiconductor laser) of Example 6. The semiconductor light emitting element shown in FIG. 11 is a surface emitting type. Since this semiconductor light emitting device constitutes a resonator for obtaining light emission, an upper reflecting mirror 128 is formed on the side of the quantum well active layer 123 opposite to the semiconductor substrate 121, and the quantum well active layer 123 A lower reflecting mirror 129 is formed on the semiconductor substrate 121 side, and at least the lower reflecting mirror 129 of the upper reflecting mirror 128 and the lower reflecting mirror 129 has a low refractive index layer and a high refractive index layer made of a dielectric material. It is configured as a dielectric multilayer film laminated alternately. Also in this configuration, the upper reflecting mirror 128 and the lower reflecting mirror 129 function as resonators for light emission from the quantum well active layer 123.

より具体的に、図11の半導体発光素子は、面方位(100)のn−GaAs基板121上に、GaAs基板121に格子整合するn−GaInPAsクラッド層122(膜厚が0.5μm),3層のGa0.6In0.40.005As0.995As井戸層とGaAsバリア層からなる多重量子井戸活性層(GaInNAs/GaAs
QW活性層)123,p−GaInPAsクラッド層124(膜厚が1.5μm),Alxy電流狭さく層125,電流注入部としてのAlAs層126(膜厚が50nm),p−GaAsコンタクト層127(膜厚が0.3μm),p−AlAsとp−GaAs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(21周期)からなるp−半導体多層膜反射鏡(AlGaAs/GaAs上部半導体多層膜反射鏡)128が順次成長されている。また、図11の半導体発光素子では、GaAs基板121の一部がクラッド層122の表面までエッチングされ、このクラッド層122上にTiO2とSiO2の組み合わせからなる誘電体多層膜反射鏡(TiO2/SiO2下部誘電体多層膜反射鏡)129が形成されている。
More specifically, the semiconductor light emitting device of FIG. 11 has an n-GaInPAs clad layer 122 (film thickness: 0.5 μm), 3 lattice-matched to the GaAs substrate 121 on the n-GaAs substrate 121 having a plane orientation (100). Multi-quantum well active layer (GaInNAs / GaAs) consisting of Ga 0.6 In 0.4 N 0.005 As 0.995 As well layer and GaAs barrier layer
QW active layer) 123, p-GaInPAs clad layer 124 (film thickness is 1.5 μm), Al x O y current narrowing layer 125, AlAs layer 126 (film thickness is 50 nm) as a current injection portion, p-GaAs contact layer 127 (thickness is 0.3 μm), p-semiconductor multilayer having a periodic structure (21 periods) in which p-AlAs and p-GaAs are alternately stacked at a thickness that is ¼ times the oscillation wavelength in each medium. A film reflector (AlGaAs / GaAs upper semiconductor multilayer reflector) 128 is sequentially grown. In the semiconductor light emitting device of FIG. 11, a part of the GaAs substrate 121 is etched to the surface of the cladding layer 122, and a dielectric multilayer reflector (TiO 2 ) made of a combination of TiO 2 and SiO 2 is formed on the cladding layer 122. / SiO 2 lower dielectric multilayer reflector) 129 is formed.

そして、電流狭さく層125,p−GaAsコンタクト層127の側面には絶縁膜(ポリイミド)130が形成され、また、p−GaAsコンタクト層127上には、p側電極131が形成され、また、GaAs基板121の裏面にはn側電極132が形成されている。   An insulating film (polyimide) 130 is formed on the side surfaces of the current narrowing layer 125 and the p-GaAs contact layer 127, and a p-side electrode 131 is formed on the p-GaAs contact layer 127. An n-side electrode 132 is formed on the back surface of the substrate 121.

図11の半導体発光素子を次のように作製した。すなわち、先ず、面方位(100)のn−GaAs基板121上に、GaAs基板121に格子整合するn−GaInPAsクラッド層122(膜厚が0.5μm),3層のGa0.6In0.40.005As0.995As井戸層とGaAsバリア層からなる多重量子井戸活性層(GaInNAs/GaAs QW活性層)123,p−GaInPAsクラッド層124(膜厚が1.5μm),Alxy電流狭さく層125,電流注入部としてのAlAs層126(膜厚が50nm),p−GaAsコンタクト層127(膜厚が0.3μm),p−AlAsとp−GaAs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(21周期)からなるp−半導体多層膜反射鏡(AlGaAs/GaAs上部半導体多層膜反射鏡)128を順次に成長させた。 The semiconductor light emitting device of FIG. 11 was produced as follows. That is, first, an n-GaInPAs clad layer 122 (film thickness is 0.5 μm) lattice-matched to the GaAs substrate 121 and a three-layer Ga 0.6 In 0.4 N 0.005 As on the n-GaAs substrate 121 of the plane orientation (100). 0.995 Multiple quantum well active layer (GaInNAs / GaAs QW active layer) 123 composed of As well layer and GaAs barrier layer, p-GaInPAs clad layer 124 (thickness: 1.5 μm), Al x O y current narrowing layer 125, current An AlAs layer 126 (film thickness is 50 nm) as an injection portion, a p-GaAs contact layer 127 (film thickness is 0.3 μm), p-AlAs and p-GaAs are ¼ times the oscillation wavelength in each medium. A p-semiconductor multilayer reflector (AlGaAs / GaAs upper semiconductor multilayer reflector) 128 having a periodic structure (21 periods) stacked alternately with a thickness is sequentially grown. It was.

ここで、井戸層のIn組成xは40%,窒素組成は0.5%とした。また、井戸層の厚さは7nmとした。圧縮歪量は約2.7%であった。成長方法はMOCVD法で行なった。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),AsH3(アルシン),PH3(フォスフィン),そして窒素の原料にはDMHy(ジメチルヒドラジン)を用いた。なお、Alを含んだp−半導体多層膜反射鏡128は、活性層123への影響の小さい低温の680℃で成長した。 Here, the In composition x of the well layer was 40%, and the nitrogen composition was 0.5%. The thickness of the well layer was 7 nm. The amount of compressive strain was about 2.7%. The growth method was the MOCVD method. TMG (trimethylgallium), TMI (trimethylindium), AsH 3 (arsine), PH 3 (phosphine) were used as raw materials, and DMHy (dimethylhydrazine) was used as a raw material for nitrogen. The p-semiconductor multilayer mirror 128 containing Al was grown at a low temperature of 680 ° C., which has little influence on the active layer 123.

そして、フォトリソグラフィ−とエッチング工程によりp−半導体多層膜反射鏡128の上部まで直径10μmの円形にメサエッチングし、更に直径30μmの円形にp−GaAsコンタクト層127をメサエッチングした。そして、絶縁膜(ポリイミド)130をコートして電流注入部126を開けて、p側電極131を形成した。そして、半導体基板121をn−GaInPAsクラッド層122の表面が現れるまでエッチングし、TiO2とSiO2の組み合せからなる誘電体多層膜反射鏡129を形成した。更に、基板121の裏面には、n側電極132を形成した。このような構造では、光取り出し部は、基板121の裏面となる。 Then, mesa etching was performed in a circular shape with a diameter of 10 μm up to the upper portion of the p-semiconductor multilayer reflector 128 by photolithography and etching processes, and the p-GaAs contact layer 127 was further mesa-etched into a circular shape with a diameter of 30 μm. Then, an insulating film (polyimide) 130 was coated and the current injection portion 126 was opened to form the p-side electrode 131. Then, the semiconductor substrate 121 was etched until the surface of the n-GaInPAs clad layer 122 appeared to form a dielectric multilayer mirror 129 made of a combination of TiO 2 and SiO 2 . Further, an n-side electrode 132 was formed on the back surface of the substrate 121. In such a structure, the light extraction portion is the back surface of the substrate 121.

この実施例6では、半導体基板121と大きな歪みを有する活性層123との間に半導体多層膜反射鏡を挿入せず、基板121側の反射鏡として誘電体多層膜を用いることで、大きな歪みを有する活性層123を劣化させずに容易に成長できた。   In the sixth embodiment, the semiconductor multilayer film reflector is not inserted between the semiconductor substrate 121 and the active layer 123 having a large strain, and the dielectric multilayer film is used as the reflector on the substrate 121 side. The active layer 123 can be easily grown without deteriorating.

換言すれば、半導体基板側の反射鏡を半導体部の外部に形成し、半導体基板と大きい歪みを有する量子井戸活性層との間にAlを含む半導体層を形成していないので、量子井戸活性層成長時のエピ基板表面の状態は良好であり、大きい歪みの量子井戸層を容易に良好に成長できた。   In other words, the reflecting mirror on the semiconductor substrate side is formed outside the semiconductor portion, and the semiconductor layer containing Al is not formed between the semiconductor substrate and the quantum well active layer having a large strain. The state of the epi-substrate surface during growth was good, and a large strained quantum well layer could be easily and satisfactorily grown.

このようにして作製した面発光レーザの発振波長は約1.3μmであった。また、しきい電流密度は1kA/cm2以下であった。In組成を30%より大きくし、圧縮歪み量を2%以上にしたことにより、従来より窒素組成を小さくでき、しきい電流密度を劇的に低減できた。高温での特性も良好であった。 The surface emitting laser produced in this way had an oscillation wavelength of about 1.3 μm. The threshold current density was 1 kA / cm 2 or less. By making the In composition larger than 30% and the compressive strain amount being 2% or more, the nitrogen composition can be made smaller than before, and the threshold current density can be dramatically reduced. The characteristics at high temperature were also good.

この実施例6では、MOCVD法での成長の例を示したが、MBE法等他の成長方法を用いることもできる。また、窒素の原料にDMHyを用いたが、活性化した窒素やNH3等他の窒素化合物を用いることもできる。 In the sixth embodiment, the example of the growth by the MOCVD method is shown, but other growth methods such as the MBE method can also be used. Further, although DMHy is used as a nitrogen raw material, other nitrogen compounds such as activated nitrogen and NH 3 can also be used.

また、上述の例では、積層構造として3重量子井戸構造(TQW)の例を示したが他の井戸数の量子井戸を用いた構造(SQW,MQW)等を用いることもできる。また各層の組成厚さ等は必要に応じて他の値を設定できる。また、活性層123にはGaInAsを用いることもできる。レーザの構造も他の構造にしてもかまわない。   In the above example, an example of a triple quantum well structure (TQW) is shown as a stacked structure, but a structure using quantum wells with other numbers of wells (SQW, MQW) or the like can also be used. Further, the composition thickness of each layer can be set to other values as required. Alternatively, GaInAs can be used for the active layer 123. The structure of the laser may be another structure.

このような大きな歪みを有した活性層の品質は、構造,成長条件に非常に敏感であり、本発明はこれに絞って述べたが、もちろん本発明の構造,成長条件等は、活性層歪みが2%より小さくても効果があるものである。   The quality of an active layer having such a large strain is very sensitive to the structure and growth conditions, and the present invention has been described in detail. Even if it is less than 2%, it is effective.

上述の各実施例では、半導体基板にGaAs基板が用いられている場合、GaAs基板上の半導体材料としてGaInAs,GaInNAsを用いるときの例を示したが、このほかにも、半導体基板にGaAs基板を用いる場合に、GaAs基板上の半導体材料としてGaInP,GaPAsを用いるとき、また半導体基板にInP基板が用いられる場合に、InP基板上の半導体材料としてGaInAs,GaInPAs,InPAs,InNPAsなどを用いるときなどにも、本発明を適用できる。すなわち、本発明は、半導体基板と格子定数の大きく異なる半導体を用いた半導体発光素子に有効となる。また、本発明は、他の発光素子,受光素子または電子素子等のIII−V族混晶半導体を用いた半導体素子にも適用できる。   In each of the above-described embodiments, when a GaAs substrate is used as the semiconductor substrate, an example in which GaInAs and GaInNAs are used as the semiconductor material on the GaAs substrate has been shown, but in addition to this, a GaAs substrate is used as the semiconductor substrate. When using GaInP, GaPAs as the semiconductor material on the GaAs substrate, or when using an InP substrate as the semiconductor substrate, such as when using GaInAs, GaInPAs, InPAs, InNPAs, etc. as the semiconductor material on the InP substrate. Also, the present invention can be applied. That is, the present invention is effective for a semiconductor light emitting device using a semiconductor having a lattice constant that is significantly different from that of the semiconductor substrate. The present invention can also be applied to semiconductor elements using III-V mixed crystal semiconductors such as other light emitting elements, light receiving elements or electronic elements.

本発明は、光通信用半導体発光素子,発光ダイオード,赤外光用フォトダイオードなどに利用可能である。
The present invention can be used for a semiconductor light emitting element for optical communication, a light emitting diode, a photodiode for infrared light, and the like.

本発明に係る半導体発光素子の構成例を示す図である。It is a figure which shows the structural example of the semiconductor light-emitting device based on this invention. 図1の半導体発光素子の活性層の一例を示す図である。It is a figure which shows an example of the active layer of the semiconductor light-emitting device of FIG. 面方位が(100)であるGaAs基板上に形成された半導体発光素子のPL特性と、面方位が(100)から〔011〕方向に15゜の角度で傾いているGaAs基板上に形成された半導体発光素子のPL特性とを示す図である。PL characteristics of a semiconductor light emitting device formed on a GaAs substrate having a plane orientation of (100) and a plane orientation of the semiconductor light emitting device inclined from the (100) to the [011] direction at an angle of 15 °. It is a figure which shows the PL characteristic of a semiconductor light-emitting device. 実施例1の半導体発光素子を示す図である。1 is a diagram showing a semiconductor light emitting device of Example 1. FIG. 図4の半導体発光素子の発振波長に対するしきい電流密度を示す図である。FIG. 5 is a diagram showing a threshold current density with respect to an oscillation wavelength of the semiconductor light emitting device of FIG. 4. 実施例2の半導体発光素子を示す図である。6 is a diagram showing a semiconductor light emitting device of Example 2. FIG. 図6の半導体発光素子の連続動作における電流−電圧特性を示す図である。It is a figure which shows the current-voltage characteristic in the continuous operation | movement of the semiconductor light-emitting device of FIG. 実施例3の半導体発光素子を示す図である。6 is a view showing a semiconductor light emitting device of Example 3. FIG. 実施例4の半導体発光素子を示す図である。6 is a diagram showing a semiconductor light emitting device of Example 4. FIG. 実施例5の半導体発光素子を示す図である。6 is a diagram showing a semiconductor light emitting device of Example 5. FIG. 実施例6の半導体発光素子を示す図である。6 is a diagram showing a semiconductor light emitting device of Example 6. FIG. 4つの試料a,b,c,dのPL特性を示す図である。It is a figure which shows the PL characteristic of four samples a, b, c, and d. ガイド層としてGaInPを用いた試料とAlGaAsを用いた試料のPL特性を示す図である。It is a figure which shows the PL characteristic of the sample which used GaInP as a guide layer, and the sample which used AlGaAs. 一般に支持されているMatthews and Blakesleeの理論に基づいて計算したGaAs基板上のGaInAs層の臨界膜厚を示す図である。It is a figure which shows the critical film thickness of the GaInAs layer on the GaAs substrate calculated based on the theory of Matthews and Blakeslee generally supported. GaInAs単一量子井戸層からのPL中心波長とPL強度との関係を示す図である。It is a figure which shows the relationship between PL center wavelength and Ga intensity | strength from a GaInAs single quantum well layer.

符号の説明Explanation of symbols

1 半導体基板
3 活性層
2 歪み量子井戸層
4 クラッド層
5 バリア層
21 n−GaAs基板
22 n−GaAsバッファ層
23 n−GaInP(As)下部クラッド層
24 GaAs光ガイド層
25a,25b Ga1-xInxAs量子井戸層
26 GaAsバリア層
27 活性層(発光層)
28 GaAs光ガイド層
29 p−GaInP(As)上部クラッド層
30 p−GaAsコンタクト層
32 p側電極
31 絶縁膜
33 n側電極
41 n−GaAs基板
42 n−GaAsバッファ層
43 n−GaInP(As)下部クラッド層
44 GaAs光ガイド層
45a,45b Ga0.67In0.330.006As0.994量子井戸層
46 GaAsバリア層
47 活性層(発光層)
48 GaAs光ガイド層
49 p−GaInP(As)上部クラッド層
50 p−GaAsコンタクト層
52 p側電極
51 絶縁膜
53 n側電極
61 n−GaAs基板
62 n−GaAsバッファ層
63 n−GaInP(As)下部クラッド層
64 GaAs光ガイド層
65a,65b Ga0.6In0.40.005As0.995量子井戸層
66 GaAsバリア層
67 活性層(発光層)
68 GaAs光ガイド層
69 p−GaInP(As)上部クラッド層
70 p−GaAsコンタクト層
72 p側電極
71 絶縁膜
73 n側電極
81 n−GaAs基板
82 n−GaAsバッファ層
83 n−GaInP(As)下部クラッド層
84 GaAs光ガイド層
85a,85b Ga0.65In0.350.007As0.993量子井戸層
86a,86b,86c GaAsバリア層
87 活性層(発光層)
88 GaAs光ガイド層
89 p−GaInP(As)上部クラッド層
90 p−GaAsコンタクト層
92 p側電極
91 絶縁膜
93 n側電極
101 GaAs基板
102 下部半導体多層膜反射鏡
103 GaAsスペ−サ層
104 活性層
105 GaAsスペ−サ層
106 電流狭さく層
107 電流注入層
108 p−GaAsコンタクト層
109 上部半導体多層膜反射鏡
110 絶縁膜
111 p側電極
112 n側電極
121 GaAs基板
122 GaInPAsクラッド層
123 活性層
124 GaInPAsクラッド層
125 電流狭さく層
126 電流注入部
127 p−GaAsコンタクト層
128 上部半導体多層膜反射鏡
129 下部誘電体多層膜反射鏡
130 絶縁膜
131 p側電極
132 n側電極
131 p側電極
132 n側電極
DESCRIPTION OF SYMBOLS 1 Semiconductor substrate 3 Active layer 2 Strained quantum well layer 4 Clad layer 5 Barrier layer 21 n-GaAs substrate 22 n-GaAs buffer layer 23 n-GaInP (As) lower clad layer 24 GaAs light guide layer 25a, 25b Ga 1-x In x As quantum well layer 26 GaAs barrier layer 27 Active layer (light emitting layer)
28 GaAs light guide layer 29 p-GaInP (As) upper clad layer 30 p-GaAs contact layer 32 p-side electrode 31 insulating film 33 n-side electrode 41 n-GaAs substrate 42 n-GaAs buffer layer 43 n-GaInP (As) Lower cladding layer 44 GaAs optical guide layer 45a, 45b Ga 0.67 In 0.33 N 0.006 As 0.994 quantum well layer 46 GaAs barrier layer 47 active layer (light emitting layer)
48 GaAs light guide layer 49 p-GaInP (As) upper cladding layer 50 p-GaAs contact layer 52 p-side electrode 51 insulating film 53 n-side electrode 61 n-GaAs substrate 62 n-GaAs buffer layer 63 n-GaInP (As) lower clad layer 64 GaAs optical guide layer 65a, 65b Ga 0.6 In 0.4 N 0.005 As 0.995 quantum well layer 66 GaAs barrier layer 67 active layer (light emitting layer)
68 GaAs light guide layer 69 p-GaInP (As) upper cladding layer 70 p-GaAs contact layer 72 p-side electrode 71 insulating film 73 n-side electrode 81 n-GaAs substrate 82 n-GaAs buffer layer 83 n-GaInP (As) Lower cladding layer 84 GaAs optical guide layer 85a, 85b Ga 0.65 In 0.35 N 0.007 As 0.993 Quantum well layer 86a, 86b, 86c GaAs barrier layer 87 Active layer (light emitting layer)
88 GaAs light guide layer 89 p-GaInP (As) upper cladding layer 90 p-GaAs contact layer 92 p-side electrode 91 insulating film 93 n-side electrode 101 GaAs substrate 102 lower semiconductor multilayer reflector 103 GaAs spacer layer 104 active Layer 105 GaAs spacer layer 106 current constriction layer 107 current injection layer 108 p-GaAs contact layer 109 upper semiconductor multilayer reflector 110 insulating film 111 p-side electrode 112 n-side electrode 121 GaAs substrate 122 GaInPAs cladding layer 123 active layer 124 GaInPAs cladding layer 125 Current constriction layer 126 Current injection portion 127 p-GaAs contact layer 128 Upper semiconductor multilayer mirror 129 Lower dielectric multilayer reflector 130 Insulating film 131 p-side electrode 132 n-side electrode 131 p-side electrode 1 32 n-side electrode

Claims (5)

半導体基板上に、歪み量子井戸層を含む活性層と、光とキャリアを閉じ込めるクラッド層とが形成され、発振波長が1.3μm帯の半導体発光素子において、前記歪み量子井戸層はInとNを含み、V族元素に占めるN組成は0〜1%であり、III族元素に占めるIn組成は30%より大きい範囲であり、半導体基板およびクラッド層に対する前記歪み量子井戸層の歪み量が2%を超える歪み量となっていることを特徴とする半導体発光素子。 An active layer including a strained quantum well layer and a cladding layer for confining light and carriers are formed on a semiconductor substrate. In a semiconductor light emitting device having an oscillation wavelength of 1.3 μm, the strained quantum well layer contains In and N. In addition, the N composition in the group V element is 0 to 1%, the In composition in the group III element is in a range larger than 30%, and the strain amount of the strain quantum well layer with respect to the semiconductor substrate and the cladding layer is 2%. A semiconductor light emitting element characterized by having a strain amount exceeding. 半導体基板上に、歪み量子井戸層を含む活性層と、光とキャリアを閉じ込めるクラッド層とが形成され、発振波長が1.3μm帯の半導体発光素子において、半導体基板およびクラッド層に対する前記歪み量子井戸層の歪み量が2%を超える歪み量となっており、半導体基板の面方位は、(100)からの傾き角度が5°の範囲内となっていることを特徴とする半導体発光素子。 An active layer including a strained quantum well layer and a cladding layer for confining light and carriers are formed on a semiconductor substrate, and the strained quantum well for the semiconductor substrate and the cladding layer in a semiconductor light emitting device having an oscillation wavelength of 1.3 μm band. A semiconductor light emitting element characterized in that the strain amount of the layer exceeds 2%, and the plane orientation of the semiconductor substrate is within a range of an inclination angle of (5) from (100). 請求項1または請求項2記載の半導体発光素子において、前記クラッド層としてGaInPまたはGaInPAsが用いられることを特徴とする半導体発光素子。 3. The semiconductor light emitting device according to claim 1, wherein GaInP or GaInPAs is used as the cladding layer. 請求項1または請求項2記載の半導体発光素子において、該半導体発光素子は、面発光型であることを特徴とする半導体発光素子。 3. The semiconductor light emitting device according to claim 1, wherein the semiconductor light emitting device is a surface light emitting type. 請求項1または請求項2記載の半導体発光素子において、前記活性層には、前記歪み量子井戸層の近傍に、応力を補償するバリア層が形成されていることを特徴とする半導体発光素子。 3. The semiconductor light emitting element according to claim 1, wherein a barrier layer for compensating stress is formed in the active layer in the vicinity of the strained quantum well layer.
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