JP4415548B2 - Light emitting device using oxynitride phosphor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light-emitting device capable of emitting whitish light, by using fluorescent materials which are excited by light from an excitation light source in a wavelength range from near ultraviolet light to short-wavelength visible light, conduct wavelength conversion, and emit a luminescent color from a greenish color to a yellowish color. <P>SOLUTION: This light-emitting device uses a light-emitting element excited by a light with a wavelength of 400 nm, is equipped with the fluorescent materials of an oxynitride fluorescent material, another fluorescent material for emitting blue light, and the other fluorescent material for emitting red light which are excited by light from the light-emitting element and conduct the wavelength conversion, and emits the whitish light, wherein the oxynitride fluorescent material is expressed by formula L<SB>X</SB>M<SB>Y</SB>O<SB>Z</SB>N<SB>((2/3)X+(4/3)Y-(2/3)Z)</SB>:R (L is at least one kind of group II element selected from Be, Mg, Ca, Sr, Ba, and Zn; M is at least one kind of group IV element selected from C, Si, Ge, Sn, Ti, Zr, and Hf; O is oxygen; N is nitrogen; R is a rare earth element; and X, Y, and Z each satisfies the following inequalities: 0&lt;X&lt;1.5, 1.5&lt;Y&lt;2.5, and 1.5&lt;Z&lt;2.5). <P>COPYRIGHT: (C)2004,JPO&amp;NCIPI

Description

【００７３】
ただし、この組成は、配合比率より推定される代表組成であり、その比率の近傍では、実用に耐える十分な特性を有する。また、各原料の配合比率を変更することにより、目的とする蛍光体の組成を変更することができる。
【００７４】
焼成は、管状炉、小型炉、高周波炉、メタル炉などを使用することができる。焼成温度は、特に限定されないが、１２００から１７００℃の範囲で焼成を行うことが好ましく、１４００から１７００℃の焼成温度が、さらに好ましい。蛍光体１１の原料は、窒化ホウ素（ＢＮ）材質の坩堝、ボートを用いて焼成を行うことが好ましい。窒化ホウ素材質の坩堝の他に、アルミナ（Ａｌ_２Ｏ_３）材質の坩堝を使用することもできる。
【００７５】
また、還元雰囲気は、窒素雰囲気、窒素−水素雰囲気、アンモニア雰囲気、アルゴン等の不活性ガス雰囲気等である。
【００７６】
以上の製造方法を使用することにより、目的とするオキシ窒化物蛍光体を得ることが可能である。
【００７７】
なお、Ｃａ_ＸＳｉ_ＹＢ_ＴＯ_ＺＮ_{（（２／３）Ｘ＋Ｙ＋Ｔ−（２／３）Ｚ−α）}：Ｅｕで表されるオキシ窒化物蛍光体は、以下のようにして製造することができる。
【００７８】
あらかじめ、Ｅｕの酸化物に、Ｂの化合物Ｈ_３ＢＯ_３を乾式混合する。Ｅｕの化合物として、酸化ユウロピウムを使用するが、前述の他の構成元素と同様、金属ユウロピウム、窒化ユウロピウムなども使用可能である。このほか、原料のＥｕは、イミド化合物、アミド化合物を用いることもできる。酸化ユウロピウムは、高純度のものが好ましいが、市販のものも使用することができる。Ｂの化合物を乾式混合するが、湿式混合することもできる。これらの混合物は、酸化されやすいものもあるため、Ａｒ雰囲気中、又は、窒素雰囲気中、グローブボックス内で、混合を行う。
【００７９】
Ｂの化合物Ｈ_３ＢＯ_３を例にとって、オキシ窒化物蛍光体の製造方法を説明するが、Ｂ以外の成分構成元素には、Ｌｉ、Ｎａ、Ｋ等があり、これらの化合物、例えば、ＬｉＯＨ・Ｈ_２Ｏ、Ｎａ_２ＣＯ_３、Ｋ_２ＣＯ_３、ＲｂＣｌ、ＣｓＣｌ、Ｍｇ（ＮＯ_３）_２、ＣａＣｌ_２・６Ｈ_２Ｏ、ＳｒＣｌ_２・６Ｈ_２Ｏ、ＢａＣｌ_２・２Ｈ_２Ｏ、ＴｉＯＳＯ_４・Ｈ_２Ｏ、ＺｒＯ（ＮＯ_３）_２、ＨｆＣｌ_４、ＭｎＯ_２、ＲｅＣｌ_５、Ｃｕ（ＣＨ_３ＣＯＯ）_２・Ｈ_２Ｏ、ＡｇＮＯ_３、ＨＡｕＣｌ_４・４Ｈ_２Ｏ、Ｚｎ（ＮＯ_３）_２・６Ｈ_２Ｏ、ＧｅＯ_２、Ｓｎ（ＣＨ_３ＣＯＯ）_２等を使用することができる。
【００８０】
ＥｕとＢの混合物を粉砕する。粉砕後のＥｕとＢの混合物の平均粒径は、約０．１μｍから１５μｍであることが好ましい。
【００８１】
上記粉砕を行った後、前述のＣａＳｉ_２Ｏ_２Ｎ_２：Ｅｕの製造工程とほぼ同様に、Ｃａの窒化物、Ｓｉの窒化物、Ｓｉの酸化物、Ｂを含有するＥｕの酸化物、を混合する。該混合後、焼成を行い、目的のオキシ窒化物蛍光体を得ることができる。
【００８２】
（第２の蛍光体１１、１０８）
蛍光体１１、１０８中には、オキシ窒化物蛍光体と共に、第２の蛍光体が含まれている。第２の蛍光体としては、Ｅｕ等のランタノイド系、Ｍｎ等の遷移金属系の元素により主に付活されるアルカリ土類ハロゲンアパタイト蛍光体、アルカリ土類金属ホウ酸ハロゲン蛍光体、アルカリ土類金属アルミン酸塩蛍光体、アルカリ土類ケイ酸塩、アルカリ土類硫化物、アルカリ土類チオガレート、アルカリ土類窒化ケイ素、ゲルマン酸塩、又は、Ｃｅ等のランタノイド系元素で主に付活される希土類アルミン酸塩、希土類ケイ酸塩、又は、Ｅｕ等のランタノイド系元素で主に賦活される有機及び有機錯体等から選ばれる少なくともいずれか１以上であることが好ましい。具体例として、下記の蛍光体を使用することができるが、これに限定されない。
【００８３】
Ｅｕ等のランタノイド系、Ｍｎ等の遷移金属系の元素により主に付活されるアルカリ土類ハロゲンアパタイト蛍光体には、Ｍ_５（ＰＯ_４）_３Ｘ：Ｒ（Ｍは、Ｓｒ、Ｃａ、Ｂａ、Ｍｇ、Ｚｎから選ばれる少なくとも１種以上である。Ｘは、Ｆ、Ｃｌ、Ｂｒ、Ｉから選ばれる少なくとも１種以上である。Ｒは、Ｅｕ、Ｍｎ、ＥｕとＭｎ、のいずれか１以上である。）などがある。
【００８４】
アルカリ土類金属ホウ酸ハロゲン蛍光体には、Ｍ_２Ｂ_５Ｏ_９Ｘ：Ｒ（Ｍは、Ｓｒ、Ｃａ、Ｂａ、Ｍｇ、Ｚｎから選ばれる少なくとも１種以上である。Ｘは、Ｆ、Ｃｌ、Ｂｒ、Ｉから選ばれる少なくとも１種以上である。Ｒは、Ｅｕ、Ｍｎ、ＥｕとＭｎ、のいずれか１以上である。）などがある。
【００８５】
アルカリ土類金属アルミン酸塩蛍光体には、ＳｒＡｌ_２Ｏ_４：Ｒ、Ｓｒ_４Ａｌ_１４Ｏ_２５：Ｒ、ＣａＡｌ_２Ｏ_４：Ｒ、ＢａＭｇ_２Ａｌ_１６Ｏ_２７：Ｒ、ＢａＭｇ_２Ａｌ_１６Ｏ_１２：Ｒ、ＢａＭｇＡｌ_１０Ｏ_１７：Ｒ（Ｒは、Ｅｕ、Ｍｎ、ＥｕとＭｎ、のいずれか１以上である。）などがある。
【００８６】
アルカリ土類硫化物蛍光体には、Ｌａ_２Ｏ_２Ｓ：Ｅｕ、Ｙ_２Ｏ_２Ｓ：Ｅｕ、Ｇｄ_２Ｏ_２Ｓ：Ｅｕなどがある。
【００８７】
Ｃｅ等のランタノイド系元素で主に賦活される希土類アルミン酸塩蛍光体には、Ｙ_３Ａｌ_５Ｏ_１２：Ｃｅ、（Ｙ_０．８Ｇｄ_０．２）_３Ａｌ_５Ｏ_１２：Ｃｅ、Ｙ_３（Ａｌ_０．８Ｇａ_０．２）_５Ｏ_１２：Ｃｅ、（Ｙ，Ｇｄ）_３（Ａｌ，Ｇａ）_５Ｏ_１２の組成式で表されるＹＡＧ系蛍光体などがある。
【００８８】
その他の蛍光体には、ＺｎＳ：Ｅｕ、Ｚｎ_２ＧｅＯ_４：Ｍｎ、ＭＧａ_２Ｓ_４：Ｅｕ（Ｍは、Ｓｒ、Ｃａ、Ｂａ、Ｍｇ、Ｚｎから選ばれる少なくとも１種以上である。Ｘは、Ｆ、Ｃｌ、Ｂｒ、Ｉから選ばれる少なくとも１種以上である。）などがある。また、Ｍ_２Ｓｉ_５Ｎ_８：Ｅｕ、ＭＳｉ_７Ｎ_１０：Ｅｕ、Ｍ_１．８Ｓｉ_５Ｏ_０．２Ｎ_８：Ｅｕ、Ｍ_０．９Ｓｉ_７Ｏ_０．１Ｎ_１０：Ｅｕ（Ｍは、Ｓｒ、Ｃａ、Ｂａ、Ｍｇ、Ｚｎから選ばれる少なくとも１種以上である。）などもある。
【００８９】
上述の第２の蛍光体は、所望に応じてＥｕに代えて、又は、Ｅｕに加えてＴｂ、Ｃｕ、Ａｇ、Ａｕ、Ｃｒ、Ｎｄ、Ｄｙ、Ｃｏ、Ｎｉ、Ｔｉから選択される１種以上を含有させることもできる。
【００９０】
また、上記蛍光体以外の蛍光体であって、同様の性能、効果を有する蛍光体も使用することができる。
【００９１】
これらの第２の蛍光体は、発光素子１０、１０１の励起光により、黄色、赤色、緑色、青色に発光スペクトルを有する蛍光体を使用することができるほか、これらの中間色である黄色、青緑色、橙色などに発光スペクトルを有する蛍光体も使用することができる。これらの第２の蛍光体を第１の蛍光体と組み合わせて使用することにより、種々の発光色を有する発光装置を製造することができる。
【００９２】
例えば、第１の蛍光体である緑色から黄色に発光するＣａＳｉ_２Ｏ_２Ｎ_２：Ｅｕ、又はＳｒＳｉ_２Ｏ_２Ｎ_２：Ｅｕと、第２の蛍光体である青色に発光する（Ｓｒ，Ｃａ）_５（ＰＯ_４）_３Ｃｌ：Ｅｕ、赤色に発光する（Ｃａ，Ｓｒ）_２Ｓｉ_５Ｎ_８：Ｅｕと、からなる蛍光体１１、１０８を使用することによって、演色性の良好な白色に発光する発光装置を提供することができる。これは、色の三源色である赤・青・緑を使用しているため、第１の蛍光体及び第２の蛍光体の配合比を変えることのみで、所望の白色光を実現することができる。
【００９３】
上記蛍光体１１、１０８の粒径は、１μｍ〜２０μｍの範囲が好ましく、より好ましくは２μｍ〜８μｍである。特に、５μｍ〜８μｍが好ましい。２μｍより小さい粒径を有する蛍光体は、凝集体を形成しやすい傾向にある。一方、５μｍ〜８μｍの粒径範囲の蛍光体は、光の吸収率及び変換効率が高い。このように、光学的に優れた特徴を有する粒径の大きな蛍光体を含有させることにより、発光装置の量産性が向上する。
【００９４】
ここで粒径は、空気透過法で得られる平均粒径を指す。具体的には、気温２５℃、湿度７０％の環境下において、１ｃｍ^３分の試料を計り取り、専用の管状容器にパッキングした後、一定圧力の乾燥空気を流し、差圧から比表面積を読みとり、平均粒径に換算した値である。本発明で用いられる蛍光体の平均粒径は２μｍ〜８μｍの範囲であることが好ましい。また、この平均粒径値を有する蛍光体が、頻度高く含有されていることが好ましい。また、粒度分布も狭い範囲に分布しているものが好ましく、特に、微粒子２μｍ以下の少ないものが好ましい。このように粒径、及び粒度分布のバラツキが小さい蛍光体を用いることにより、より色ムラが抑制され、良好な色調を有する発光装置が得られる。
【００９５】
発光装置２における蛍光体１０８の配置場所は発光素子１０１との位置関係において種々の場所に配置することができる。例えば、発光素子１０１を被覆するモールド材料中に、蛍光体１０８を含有させることができる。また、発光素子１０１と蛍光体１０８とを、間隙をおいて配置しても良いし、発光素子１０１の上部に蛍光体１０８を、直接載置しても良い。
【００９６】
（コーティング部材１２、１０９）
蛍光体１１、１０８は、有機材料である樹脂や無機材料であるガラスなど種々のコーティング部材（バインダー）を用いて、付着させることができる。コーティング部材１２、１０９は、蛍光体１１、１０８を発光素子１０、１０１や窓部１０７等に固着させるためのバインダーとしての役割を有することもある。コーティング部材（バインダー）として有機物を使用する場合、具体的材料として、エポキシ樹脂、アクリル樹脂、シリコーンなどの耐候性に優れた透明樹脂が好適に用いられる。特に、シリコーンを用いると、信頼性に優れ、且つ蛍光体１１、１０８の分散性を向上させることができ好ましい。
【００９７】
また、コーティング部材（バインダー）１２、１０９として、窓部１０７の熱膨張率と近似である無機物を使用すると、蛍光体１０８を良好に前記窓部１０７に密着させることができ好ましい。具体的方法として、沈降法やゾル−ゲル法、スプレー法等を用いることができる。例えば、蛍光体１１、１０８に、シラノール（Ｓｉ（ＯＥｔ）_３ＯＨ）、及びエタノールを混合してスラリーを形成し、該スラリーをノズルから吐出させた後、３００℃にて３時間加熱してシラノールをＳｉＯ_２とし、蛍光体を所望の場所に固着させることができる。
【００９８】
また、無機物である結着剤をコーティング部材（バインダー）１２、１０９として用いることもできる。結着剤とは、いわゆる低融点ガラスであり、微細な粒子であり、且つ紫外から可視領域のふく射線に対して吸収が少なく、コーティング部材（バインダー）１２、１０９中にて極めて安定であることが好ましい。
【００９９】
また、粒径の大きな蛍光体をコーティング部材（バインダー）１２、１０９に付着させる場合、融点が高くても粒子が超微粉体である結着剤、例えば、シリカ、アルミナ、あるいは沈殿法で得られる細かい粒度のアルカリ土類金属のピロリン酸塩、正りん酸塩などを使用することが好ましい。これらの結着剤は、単独、若しくは互いに混合して用いることができる。
【０１００】
ここで、上記結着剤の塗布方法について述べる。結着剤は、結着効果を十分に高めるため、ビヒクル中に湿式粉砕して、スラリー状にして、結着剤スラリーとして用いることが好ましい。前記ビヒクルとは、有機溶媒あるいは脱イオン水に少量の粘結剤を溶解して得られる高粘度溶液である。例えば、有機溶媒である酢酸ブチルに対して粘結剤であるニトロセルロースを１ｗｔ％含有させることにより、有機系ビヒクルが得られる。
【０１０１】
このようにして得られた結着剤スラリーに、蛍光体１１、１０８を含有させて塗布液を作製する。塗布液中のスラリーの添加量は、塗布液中の蛍光体量に対してスラリー中の結着剤の総量が、１〜３％ｗｔ程度とすることができる。光束維持率の低下を抑制するため、結着剤の添加量が少ない方が好ましい。
【０１０２】
前記塗布液を前記窓部１０７の背面に塗布する。その後、温風あるいは熱風を吹き込み乾燥させる。最後に４００℃〜７００℃の温度でベーキングを行い、前記ビヒクルを飛散させる。これにより所望の場所に蛍光体層が結着剤にて付着される。
【０１０３】
（発光素子１０、１０１）
本発明において発光素子１０、１０１は、蛍光体を効率よく励起可能な発光波長を発光できる発光層を有する半導体発光素子が好ましい。このような半導体発光素子の材料として、ＢＮ、ＳｉＣ、ＺｎＳｅやＧａＮ、ＩｎＧａＮ、ＩｎＡｌＧａＮ、ＡｌＧａＮ、ＢＡｌＧａＮ、ＢＩｎＡｌＧａＮなど種々の半導体を挙げることができる。同様に、これらの元素に不純物元素としてＳｉやＺｎなどを含有させ発光中心とすることもできる。蛍光体１１、１０８を効率良く励起できる紫外領域から可視光の短波長を効率よく発光可能な発光層の材料として特に、窒化物半導体（例えば、ＡｌやＧａを含む窒化物半導体、ＩｎやＧａを含む窒化物半導体としてＩｎ_ＸＡｌ_ＹＧａ_{１−Ｘ−Ｙ}Ｎ、０≦Ｘ、０≦Ｙ、Ｘ＋Ｙ≦１）がより好適に挙げられる。
【０１０４】
また、半導体の構造としては、ＭＩＳ接合、ＰＩＮ接合やｐｎ接合などを有するホモ構造、ヘテロ構造あるいはダブルへテロ構成のものが好適に挙げられる。半導体層の材料やその混晶比によって発光波長を種々選択することができる。また、半導体活性層を量子効果が生ずる薄膜に形成させた単一量子井戸構造や多重量子井戸構造とすることでより出力を向上させることもできる。
【０１０５】
発光素子１０、１０１に、窒化物半導体を使用した場合、半導体用基板にはサファイア、スピネル、ＳｉＣ、Ｓｉ、ＺｎＯ、ＧａＡｓ、ＧａＮ等の材料が好適に用いられる。結晶性の良い窒化物半導体を量産性よく形成させるためにはサファイア基板を利用することが好ましい。このサファイア基板上にＨＶＰＥ法やＭＯＣＶＤ法などを用いて窒化物半導体を形成させることができる。サファイア基板上にＧａＮ、ＡｌＮ、ＧａＡＩＮ等の低温で成長させ非単結晶となるバッファ層を形成しその上にｐｎ接合を有する窒化物半導体を形成させる。
【０１０６】
窒化物半導体を使用したｐｎ接合を有する紫外領域を効率よく発光可能な発光素子例として、バッファ層上に、サファイア基板のオリフラ面と略垂直にＳｉＯ_２をストライプ状に形成する。ストライプ上にＨＶＰＥ法を用いてＧａＮをＥＬＯＧ（Epitaxial Lateral Over Grows GaN）成長させる。続いて、ＭＯＣＶＤ法により、ｎ型窒化ガリウムで形成した第１のコンタクト層、ｎ型窒化アルミニウム・ガリウムで形成させた第１のクラッド層、窒化インジウム・アルミニウム・ガリウムの井戸層と窒化アルミニウム・ガリウムの障壁層を複数積層させた多重量子井戸構造とされる活性層、ｐ型窒化アルミニウム・ガリウムで形成した第２のクラッド層、ｐ型窒化ガリウムで形成した第２のコンタクト層を順に積層させたダブルへテロ構成などの構成が挙げられる。活性層をリッジストライプ形状としガイド層で挟むと共に共振器端面を設け本発明に利用可能な半導体レーザー素子とすることもできる。
【０１０７】
窒化物半導体は、不純物をドープしない状態でｎ型導電性を示す。発光効率を向上させるなど所望のｎ型窒化物半導体を形成させる場合は、ｎ型ドーパントとしてＳｉ、Ｇｅ、Ｓｅ、Ｔｅ、Ｃ等を適宜導入することが好ましい。一方、ｐ型窒化物半導体を形成させる場合は、ｐ型ドーパントであるＺｎ、Ｍｇ、Ｂｅ、Ｃａ、Ｓｒ、Ｂａ等をドープさせることが好ましい。窒化物半導体は、ｐ型ドーパントをドープしただけではｐ型化しにくいためｐ型ドーパント導入後に、炉による加熱やプラズマ照射等により低抵抗化させることが好ましい。サファイア基板をとらない場合は、第１のコンタクト層の表面までｐ型側からエンチングさせコンタクト層を露出させる。各コンタクト層上にそれぞれ電極形成後、半導体ウエハーからチップ状にカットさせることで窒化物半導体からなる発光素子を形成させることができる。
【０１０８】
本発明の発光装置において、量産性よく形成させるためには、蛍光体１１、１０８を発光素子１０、１０１に固着する際に、樹脂を利用して形成することが好ましい。この場合、蛍光体１１、１０８からの発光波長と透光性樹脂の劣化等を考慮して、発光素子１０、１０１は紫外域に発光スペクトルを有し、その発光ピーク波長は、３６０ｎｍ以上４２０ｎｍ以下のものや、４５０ｎｍ以上４７０ｎｍ以下のものを使用することが好ましい。
【０１０９】
ここで、本発明で用いられる半導体発光素子１０、１０１は、不純物濃度１０^１７〜１０^２０／ｃｍ^３で形成されるｎ型コンタクト層のシート抵抗と、透光性ｐ電極のシート抵抗とが、Ｒｐ≧Ｒｎの関係となるように調節されていることが好ましい。ｎ型コンタクト層は、例えば膜厚３〜１０μｍ、より好ましくは４〜６μｍに形成されると好ましく、そのシート抵抗は１０〜１５Ω／□と見積もられることから、このときのＲｐは前記シート抵抗値以上のシート抵抗値を有するように薄膜に形成するとよい。また、透光性ｐ電極は、膜厚が１５０μｍ以下の薄膜で形成されていてもよい。
【０１１０】
また、透光性ｐ電極が、金および白金族元素の群から選択された１種と、少なくとも１種の他の元素とから成る多層膜または合金で形成される場合には、含有されている金または白金族元素の含有量により透光性ｐ電極のシート抵抗の調整をすると安定性および再現性が向上される。金または金属元素は、本発明に使用する半導体発光素子の波長領域における吸収係数が高いので、透光性ｐ電極に含まれる金又は白金族元素の量は少ないほど透過性がよくなる。従来の半導体発光素子はシート抵抗の関係がＲｐ≦Ｒｎであったが、本発明ではＲｐ≧Ｒｎであるので、透光性ｐ電極は従来のものと比較して薄膜に形成されることとなるが、このとき金または白金族元素の含有量を減らすことで薄膜化が容易に行える。
【０１１１】
上述のように、本発明で用いられる半導体発光素子１０、１０１は、ｎ型コンタクト層のシート抵抗ＲｎΩ／□と、透光性ｐ電極のシート抵抗ＲｐΩ／□とが、Ｒｐ≧Ｒｎの関係を成していることが好ましい。半導体発光素子１０、１０１として形成した後にＲｎを測定するのは難しく、ＲｐとＲｎとの関係を知るのは実質上不可能であるが、発光時の光強度分布の状態からどのようなＲｐとＲｎとの関係になっているのかを知ることができる。
【０１１２】
透光性ｐ電極とｎ型コンタクト層とがＲｐ≧Ｒｎの関係であるとき、前記透光性ｐ電極上に接して延長伝導部を有するｐ側台座電極を設けると、さらなる外部量子効率の向上を図ることができる。延長伝導部の形状及び方向に制限はなく、延長伝導部が衛線上である場合、光を遮る面積が減るので好ましいが、メッシュ状でもよい。また形状は、直線状以外に、曲線状、格子状、枝状、鉤状でもよい。このときｐ側台座電極の総面積に比例して遮光効果が増大するため、遮光効果が発光増強効果を上回らないように延長導電部の線幅及び長さを設計するのがよい。
【０１１３】
（発光素子１０、１０１）
発光素子１０、１０１は、上述の紫外発光の発光素子と異なる青色系に発光する発光素子を使用することもできる。青色系に発光する発光素子１０、１０１は、ＩＩＩ族窒化物系化合物発光素子であることが好ましい。発光素子１０、１０１は、例えばサファイア基板１上にＧａＮバッファ層を介して、Ｓｉがアンドープのｎ型ＧａＮ層、Ｓｉがドープされたｎ型ＧａＮからなるｎ型コンタクト層、アンドープＧａＮ層、多重量子井戸構造の発光層（ＧａＮ障壁層／ＩｎＧａＮ井戸層の量子井戸構造）、Ｍｇがドープされたｐ型ＧａＮからなるｐ型ＧａＮからなるｐクラッド層、Ｍｇがドープされたｐ型ＧａＮからなるｐ型コンタクト層が順次積層された積層構造を有し、以下のように電極が形成されている。但し、この構成と異なる発光素子も使用できる。
【０１１４】
ｐオーミック電極は、ｐ型コンタクト層上のほぼ全面に形成され、そのｐオーミック電極上の一部にｐパッド電極が形成される。
【０１１５】
また、ｎ電極は、エッチングによりｐ型コンタクト層からアンドープＧａＮ層を除去してｎ型コンタクト層の一部を露出させ、その露出された部分に形成される。
【０１１６】
なお、本実施の形態では、多重量子井戸構造の発光層を用いたが、本発明は、これに限定されるものではなく、例えば、ＩｎＧａＮを利用した単一量子井戸構造としても良いし、Ｓｉ、ＺｎがドープされたＧａＮを利用しても良い。
【０１１７】
また、発光素子１０、１０１の発光層は、Ｉｎの含有量を変化させることにより、４２０ｎｍから４９０ｎｍの範囲において主発光ピーク波長を変更することができる。また、発光ピーク波長は、上記範囲に限定されるものではなく、３６０〜５５０ｎｍに発光ピーク波長を有しているものを使用することができる。
【０１１８】
（コーティング部材１２、１０９）
コーティング部材１２（光透光性材料）は、リードフレーム１３のカップ内に設けられるものであり発光素子１０の発光を変換する蛍光体１１と混合して用いられる。コーティング部材１２の具体的材料としては、エポキシ樹脂、ユリア樹脂、シリコーン樹脂などの温度特性、耐候性に優れた透明樹脂、シリカゾル、ガラス、無機バインダーなどが用いられる。また、蛍光体と共に拡散剤、チタン酸バリウム、酸化チタン、酸化アルミニウムなどを含有させても良い。また、光安定化剤や着色剤を含有させても良い。
【０１１９】
（リードフレーム１３）
リードフレーム１３は、マウントリード１３ａとインナーリード１３ｂとから構成される。
【０１２０】
マウントリード１３ａは、発光素子１０を配置させるものである。マウントリード１３ａの上部は、カップ形状になっており、カップ内に発光素子１０をダイボンドし、該発光素子１０の外周面を、カップ内を前記蛍光体１１と前記コーティング部材１２とで覆っている。カップ内に発光素子１０を複数配置しマウントリード１３ａを発光素子１０の共通電極として利用することもできる。この場合、十分な電気伝導性と導電性ワイヤ１４との接続性が求められる。発光素子１０とマウントリード１３ａのカップとのダイボンド（接着）は、熱硬化性樹脂などによって行うことができる。熱硬化性樹脂としては、エポキシ樹脂、アクリル樹脂、イミド樹脂などが挙げられる。また、フェースダウン発光素子１０などによりマウントリード１３ａとダイボンドすると共に電気的接続を行うには、Ａｇ―エースと、カーボンペースト、金属バンプなどを用いることができる。また、無機バインダーを用いることもできる。
【０１２１】
インナーリード１３ｂは、マウントリード１３ａ上に配置された発光素子１０の電極３から延びる導電性ワイヤ１４との電気的接続を図るものである。インナーリード１３ｂは、マウントリード１３ａとの電気的接触によるショートを避けるため、マウントリード１３ａから離れた位置に配置することが好ましい。マウントリード１３ａ上に複数の発光素子１０を設けた場合は、各導電性ワイヤ同士が接触しないように配置できる構成にする必要がある。インナーリード１３ｂは、マウントリード１３ａと同様の材質を用いることが好ましく、鉄、銅、鉄入り銅、金、白金、銀などを用いることができる。
【０１２２】
（導電性ワイヤ）
導電性ワイヤ１４は、発光素子１０の電極３とリードフレーム１３とを電気的に接続するものである。導電性ワイヤ１４は、電極３とオーミック性、機械的接続性、電気導電性及び熱伝導性が良いものが好ましい。導電性ワイヤ１４の具体的材料としては、金、銅、白金、アルミニウムなどの金属及びそれらの合金などが好ましい。
【０１２３】
（モールド部材）
モールド部材１５は、発光素子１０、蛍光体１１、コーティング部材１２、リードフレーム１３及び導電性ワイヤ１４などを外部から保護するために設けられている。モールド部材１５は、外部からの保護目的の他に、視野角を広げたり、発光素子１０からの指向性を緩和したり、発光を収束、拡散させたりする目的も併せ持っている。これらの目的を達成するためモールド部材は、所望の形状にすることができる。また、モールド部材１５は、凸レンズ形状、凹レンズ形状の他、複数積層する構造であっても良い。モールド部材１５の具体的材料としては、エポキシ樹脂、ユリア樹脂、シリコーン樹脂、シリカゾル、ガラスなどの透光性、耐候性、温度特性に優れた材料を使用することができる。モールド部材１５には、拡散剤、着色剤、紫外線吸収剤や蛍光体を含有させることもできる。拡散剤としては、チタン酸バリウム、酸化チタン、酸化アルミニウム等が好ましい。コーティング部材１２との材質の反発性を少なくするため、屈折率を考慮するため、同材質を用いることが好ましい。
【０１２４】
以下、本発明に係る蛍光体、発光装置について実施例を挙げて説明するが、この実施例に限定されるものではない。
【０１２５】
なお、温度特性は、２５℃の発光輝度を１００％とする相対輝度で示す。粒径は、前述の平均粒径を示し、Ｆ．Ｓ．Ｓ．Ｓ．Ｎｏ．（Fisher Sub Sieve Sizer's No.）という空気透過法による値である。
【０１２６】
【実施例】
以下、本発明の実施例について詳述する。
【０１２７】
（蛍光体）
＜実施例１乃至５＞
表１は、本発明に係るオキシ窒化物蛍光体の実施例１乃至５の特性を示す。
【０１２８】
また、図３は、実施例１乃至５のオキシ窒化物蛍光体をＥｘ＝４００ｎｍで励起したときの発光スペクトルを示す図である。図４は、実施例１乃至５のオキシ窒化物蛍光体をＥｘ＝４６０ｎｍで励起したときの発光スペクトルを示す図である。図５は、実施例１乃至５のオキシ窒化物蛍光体の励起スペクトルを示す図である。図６は、実施例１乃至５のオキシ窒化物蛍光体の反射スペクトルを示す図である。図７は、実施例１のオキシ窒化物蛍光体を撮影したＳＥＭ（走査電子顕微鏡）写真である。ここで、色名と色度座標との関係は、ＪＩＳ Ｚ８１１０を参酌する。
【０１２９】
【表１】

【０１３０】
実施例１は、ＣａＳｉ_２Ｏ_２Ｎ_２：Ｅｕである。実施例２は、Ｃａ_０．９０Ｍｇ_０．１０Ｓｉ_２Ｏ_２Ｎ_２：Ｅｕである。実施例３は、ＳｒＳｉ_２Ｏ_２Ｎ_２：Ｅｕである。実施例４は、Ｓｒ_０．９０Ｍｇ_０．１０Ｓｉ_２Ｏ_２Ｎ_２：Ｅｕである。実施例５は、ＢａＳｉ_２Ｏ_２Ｎ_２：Ｅｕである。
【０１３１】
まず、原料は、Ｃａ_３Ｎ_２、Ｓｉ_３Ｎ_４、ＳｉＯ_２、Ｅｕ_２Ｏ_３を使用した。該原料を、それぞれ０．１〜３．０μｍに粉砕した。粉砕後、実施例１は、下記の数量の原料を使用した。
Ｃａ_３Ｎ_２：６．０１ｇ
Ｓｉ_３Ｎ_４：５．９９ｇ
ＳｉＯ_２：７．３６ｇ
Ｅｕ_２Ｏ_３：０．６６ｇ
上記数量を秤量した後、Ｃａ_３Ｎ_２、Ｓｉ_３Ｎ_４、ＳｉＯ_２、Ｅｕ_２Ｏ_３を、窒素雰囲気中、グローブボックス内で、均一になるまで混合した。実施例１乃至５において、Ｅｕ濃度は０．４３ｍｏｌ％である。
【０１３２】
実施例１において、原料の混合比率（モル比）は、Ｃａ_３Ｎ_２：Ｓｉ_３Ｎ_４：ＳｉＯ_２：Ｅｕ_２Ｏ_３＝１：０．５１：３．０２：０．０４６である。この混合比率になるように、Ｃａ_３Ｎ_２（分子量１４８．３）を６．０１ｇ、Ｓｉ_３Ｎ_４（分子量１４０．３）を５．９９ｇ、ＳｉＯ_２（分子量６０．０９）を７．３６ｇ、Ｅｕ_２Ｏ_３（分子量３５２．０）を０．６６ｇになるように秤量し、混合を行った。
【０１３３】
上記化合物を混合し、アンモニア雰囲気中で、窒化ホウ素坩堝に投入し、約１５００℃で約５時間、焼成を行った。
【０１３４】
これにより、目的とするオキシ窒化物蛍光体を得た。得られたオキシ窒化物蛍光体の理論組成は、ＣａＳｉ_２Ｏ_２Ｎ_２：Ｅｕである。
【０１３５】
実施例１のオキシ窒化物蛍光体のＯとＮとの重量％を測定すると、全量中にＯが１９．３重量％、Ｎが１４．５重量％含まれていた。ＯとＮの重量比は、Ｏ：Ｎ＝１：０．７５である。
【０１３６】
実施例に係るオキシ窒化物蛍光体は、窒化ホウ素材質の坩堝を用い、アンモニア雰囲気中で焼成を行っている。坩堝に、金属製の坩堝を使用することはあまり好ましいとはいえない。金属製の坩堝を使用した場合、坩堝が浸食され、発光特性の低下を引き起こすことが考えられるからである。従って、アルミナなどのセラミックス製の坩堝を使用することが好ましい。
【０１３７】
実施例２は、Ｃａの一部をＭｇに置換したオキシ窒化物蛍光体である。実施例２は、窒化マグネシウムＭｇ_３Ｎ_２（高純度化学製 98% MGI02PB）（分子量１０１．０）を用い、原料の混合比率（モル比）が、Ｃａ_３Ｎ_２：Ｍｇ_３Ｎ_２：Ｓｉ_３Ｎ_４：ＳｉＯ_２：Ｅｕ_２Ｏ_３＝１：０．１２：０．５７：３．３７：０．０５２となるように、細かく砕いた粉末を、下記の数量、秤量した。
Ｃａ_３Ｎ_２：５．４４ｇ
Ｍｇ_３Ｎ_２：０．４３ｇ
Ｓｉ_３Ｎ_４：６．０５ｇ
ＳｉＯ_２：７．４３ｇ
Ｅｕ_２Ｏ_３：０．６７ｇ
実施例１と同条件で、該原料を混合し、焼成を行った。
【０１３８】
実施例３は、実施例１のＣａをＳｒに置換したオキシ窒化物蛍光体である。実施例３は、窒化ストロンチウムＳｒ_３Ｎ_４（分子量２９０．９）を用い、原料の混合比率（モル比）が、Ｓｒ_３Ｎ_２：Ｓｉ_３Ｎ_４：ＳｉＯ_２：Ｅｕ_２Ｏ_３＝１：０．５１：３．０２：０．０４６となるように、細かく砕いた粉末を、下記の数量、秤量した。
Ｓｒ_３Ｎ_２：９．１４ｇ
Ｓｉ_３Ｎ_４：４．６５ｇ
ＳｉＯ_２：５．７１ｇ
Ｅｕ_２Ｏ_３：０．５１ｇ
実施例３は、実施例１と同条件で、該原料を混合し、焼成を行った。得られた実施例３のオキシ窒化物蛍光体のＯとＮとの重量％を測定すると、全量中にＯが１５．３重量％、Ｎが１１．２重量％含まれていた。ＯとＮの重量比は、Ｏ：Ｎ＝１：０．７３である。
【０１３９】
実施例４は、実施例２のＣａをＳｒに置換したオキシ窒化物蛍光体である。実施例４は、原料の混合比率（モル比）が、Ｓｒ_３Ｎ_２：Ｍｇ_３Ｎ_２：Ｓｉ_３Ｎ_４：ＳｉＯ_２：Ｅｕ_２Ｏ_３＝１：０．１２：０．５７：３．３７：０．０５２となるように、細かく砕いた粉末を、下記の数量、秤量した。
Ｓｒ_３Ｎ_２：８．４６ｇ
Ｍｇ_３Ｎ_２：０．３４ｇ
Ｓｉ_３Ｎ_４：４．８０ｇ
ＳｉＯ_２：５．８９ｇ
Ｅｕ_２Ｏ_３：０．５３ｇ
実施例１と同条件で、該原料を混合し、焼成を行った。
【０１４０】
実施例５は、実施例１のＣａをＢａに置換したオキシ窒化物蛍光体である。実施例５は、窒化バリウムＢａ_３Ｎ_２（分子量３１６．６）を用い、原料の混合比率（モル比）が、Ｂａ_３Ｎ_２：Ｓｉ_３Ｎ_４：ＳｉＯ_２：Ｅｕ_２Ｏ_３＝１：０．７６：０．２２：０．０３３となるように、細かく砕いた粉末を、下記の数量、秤量した。
Ｂａ_３Ｎ_２：１１．２ｇ
Ｓｉ_３Ｎ_４：３．７７ｇ
ＳｉＯ_２：４．６３ｇ
Ｅｕ_２Ｏ_３：０．４２ｇ
実施例１と同条件で、該原料を混合し、焼成を行った。
【０１４１】
実施例１乃至５の焼成品は、いずれも、結晶性の粉体若しくは粒体である。粒径は、ほぼ１〜５μｍであった。
【０１４２】
実施例１乃至５のオキシ窒化物蛍光体の励起スペクトルの測定を行った。測定の結果、４９０ｎｍよりも短波長側で強く励起される。
【０１４３】
Ｅｘ＝４６０ｎｍで実施例１乃至５のオキシ窒化物蛍光体を励起した。Ｅｘ＝４６０ｎｍは、青色発光素子でよく使われる波長域であるため、該波長域で励起を行った。その結果、実施例１のオキシ窒化物蛍光体は、色調ｘ＝０．４３７、色調ｙ＝０．５４５の黄緑色領域に発光色を有する。実施例４のオキシ窒化物蛍光体は、色調ｘ＝０．３５１、色調ｙ＝０．６１４の黄緑色領域に発光色を有する。実施例１乃至５のオキシ窒化物蛍光体のいずれも、従来の蛍光体よりも、高い発光効率を示した。
【０１４４】
Ｅｘ＝４００ｎｍで実施例１乃至５のオキシ窒化物蛍光体を励起した。実施例１のオキシ窒化物蛍光体は、色調ｘ＝０．４３４、色調ｙ＝０．５４３の黄緑色領域に発光色を有する。実施例３のオキシ窒化物蛍光体は、色調ｘ＝０．３４９、色調ｙ＝０．６０８の黄緑色領域に発光色を有する。実施例１乃至５のオキシ窒化物蛍光体のいずれも、従来の蛍光体よりも、高い発光効率を示した。
【０１４５】
また、温度特性は、極めて良好であった。温度特性は、２５℃の発光輝度を１００％とする相対輝度で示す。粒径は、Ｆ．Ｓ．Ｓ．Ｓ．Ｎｏ．（Fisher Sub Sieve Sizer's No.）という空気透過法による値である。実施例１乃至５の温度特性は、１００℃のとき、９５〜１００％である。２００℃のとき、６５〜９０％であった。
【０１４６】
これら上記オキシ窒化物蛍光体のＸ線回折像を測定したところ、いずれもシャープな回折ピークを示し、得られた蛍光体が、規則性を有する結晶性の化合物であることが明らかとなった。
【０１４７】
＜実施例６乃至１５＞
表２は、本発明に係るオキシ窒化物蛍光体の実施例６乃至１５の特性を示す。
【０１４８】
また、図８は、実施例６乃至１０のオキシ窒化物蛍光体をＥｘ＝４００ｎｍで励起したときの発光スペクトルを示す図である。図９は、実施例６乃至１０のオキシ窒化物蛍光体をＥｘ＝４６０ｎｍで励起したときの発光スペクトルを示す図である。図１０は、実施例１１乃至１５のオキシ窒化物蛍光体をＥｘ＝４００ｎｍで励起したときの発光スペクトルを示す図である。図１１は、実施例１１乃至１５のオキシ窒化物蛍光体をＥｘ＝４６０ｎｍで励起したときの発光スペクトルを示す図である。図１２は、実施例１１乃至１５のオキシ窒化物蛍光体の励起スペクトルを示す図である。図１３は、実施例１１乃至１５のオキシ窒化物蛍光体の反射スペクトルを示す図である。
【０１４９】
【表２】

【０１５０】
実施例６乃至１０は、Ｓｒ_ＸＣａ_{（１−Ｘ）}Ｓｉ_２Ｏ_２Ｎ_２：Ｅｕ（０≦Ｘ≦１）で表され、ＳｒとＣａとのモル比を変えて製造を行っている。
【０１５１】
実施例６乃至１０は、実施例１とほぼ同様の条件でオキシ窒化物蛍光体の製造を行った。原料は、Ｓｒ_３Ｎ_２、Ｃａ_３Ｎ_２、Ｓｉ_３Ｎ_４、ＳｉＯ_２、Ｅｕ_２Ｏ_３を使用した。該原料を所定の数量に秤量した後、Ｓｒ_３Ｎ_２、Ｃａ_３Ｎ_２、Ｓｉ_３Ｎ_４、ＳｉＯ_２、Ｅｕ_２Ｏ_３を、窒素雰囲気中、グローブボックス内で、均一になるまで混合した。実施例６乃至１５において、Ｅｕ濃度は０．４３ｍｏｌ％である。
【０１５２】
上記化合物を混合し、アンモニア雰囲気中で、窒化ホウ素坩堝に投入し、約１４５０℃で約５時間、焼成を行った。
【０１５３】
これにより、目的とするオキシ窒化物蛍光体が製造された。
【０１５４】
実施例６乃至１０は、発光輝度、量子効率は、実施例６を基準として、相対値で表している。
【０１５５】
この結果から、４００ｎｍ近傍の光源で実施例６乃至１０を励起させたとき、ＳｒとＣａとを混合させたときの方が、Ｃａのみのときよりも、高い発光輝度、量子効率を示した。一方、４６０ｎｍ近傍の光源で実施例６乃至１０を励起させたとき、Ｓｒ：Ｃａ＝７：３のときが、最も発光効率が高かった。また、Ｃａの一部を置換して、Ｓｒを増やしていくに従って、発光効率の向上を図ることができる。また、ＳｒとＣａのモル比を変えることにより、色調を変化させることが可能である。
【０１５６】
実施例１１乃至１５は、Ｓｒ_ＸＣａ_{（１０−Ｘ）}Ｓｉ_２Ｏ_２Ｎ_２：Ｅｕ（０≦Ｘ≦１０）で表され、ＳｒとＣａとのモル比を変えて製造を行っている。
【０１５７】
実施例１１乃至１５は、実施例１とほぼ同様の条件でオキシ窒化物蛍光体の製造を行った。原料は、Ｓｒ_３Ｎ_２、Ｃａ_３Ｎ_２、Ｓｉ_３Ｎ_４、ＳｉＯ_２、Ｅｕ_２Ｏ_３を使用した。該原料を所定の数量に秤量した後、Ｓｒ_３Ｎ_２、Ｃａ_３Ｎ_２、Ｓｉ_３Ｎ_４、ＳｉＯ_２、Ｅｕ_２Ｏ_３を、窒素雰囲気中、グローブボックス内で、均一になるまで混合した。実施例６乃至１５において、Ｅｕ濃度は０．４３ｍｏｌ％である。
【０１５８】
上記化合物を混合し、アンモニア雰囲気中で、窒化ホウ素坩堝に投入し、約１５５０℃で約５時間、焼成を行った。
【０１５９】
これにより、目的とするオキシ窒化物蛍光体が製造された。
【０１６０】
実施例１１乃至１５は、発光輝度、量子効率は、実施例１５を基準として、相対値で表している。
【０１６１】
この結果から、４００ｎｍ近傍の光源で実施例１１乃至１５を励起させたとき、ＳｒとＣａとを混合させたときの方が、Ｓｒのみのときよりも、高い発光輝度、量子効率を示した。また、Ｓｒ：Ｃａのモル比が、Ｓｒ：Ｃａ＝６：４乃至９：１のとき発光効率の向上を図ることができる。特に、Ｓｒ：Ｃａ＝７：３乃至８：２の時が、発光輝度、量子効率ともに高い値を示している。さらに、ＳｒとＣａのモル比を変えることにより、色調を変化させることが可能である。
【０１６２】
＜実施例１６乃至２０＞
表３は、本発明に係るオキシ窒化物蛍光体の実施例１０、１６乃至２０の特性を示す。
【０１６３】
また、図１４は、実施例１０、１６乃至２０のオキシ窒化物蛍光体をＥｘ＝４００ｎｍで励起したときの発光スペクトルを示す図である。図１５は、実施例１０、１６乃至２０のオキシ窒化物蛍光体をＥｘ＝４６０ｎｍで励起したときの発光スペクトルを示す図である。図１６は、実施例１０、１６乃至２０のオキシ窒化物蛍光体の励起スペクトルを示す図である。図１７は、実施例１０、１６乃至２０のオキシ窒化物蛍光体の反射スペクトルを示す図である。
【０１６４】
【表３】

【０１６５】
実施例１０、１６乃至２０は、Ｓｒ_ＸＢａ_{（１−Ｘ）}Ｓｉ_２Ｏ_２Ｎ_２：Ｅｕ（０≦Ｘ≦１）で表され、ＳｒとＢａとのモル比を変えて製造を行っている。
【０１６６】
実施例１０、１６乃至２０は、実施例１とほぼ同様の条件でオキシ窒化物蛍光体の製造を行った。原料は、Ｓｒ_３Ｎ_２、Ｂａ_３Ｎ_２、Ｓｉ_３Ｎ_４、ＳｉＯ_２、Ｅｕ_２Ｏ_３を使用した。該原料を所定の数量に秤量した後、Ｓｒ_３Ｎ_２、Ｂａ_３Ｎ_２、Ｓｉ_３Ｎ_４、ＳｉＯ_２、Ｅｕ_２Ｏ_３を、窒素雰囲気中、グローブボックス内で、均一になるまで混合した。実施例１０、１６乃至２０において、Ｅｕ濃度は０．４３ｍｏｌ％である。
【０１６７】
上記化合物を混合し、アンモニア雰囲気中で、窒化ホウ素坩堝に投入し、約１４５０℃で約５時間、焼成を行った。
【０１６８】
これにより、目的とするオキシ窒化物蛍光体が製造された。
【０１６９】
実施例１０、１６乃至２０は、発光輝度、量子効率は、実施例１０を基準として、相対値で表している。
【０１７０】
この結果から、４００ｎｍ、４６０ｎｍ近傍の光源で実施例１０、１６乃至２０を励起させたとき、Ｓｒ：Ｂａ＝２：８で混合させたときより、Ｓｒ：Ｂａ＝６：４乃至８：２で混合させたときの方が、高い発光輝度、量子効率を示した。また、Ｂａの一部を置換して、Ｓｒを増やしていくに従って、発光効率の向上を図ることができる。また、ＳｒとＣａのモル比を変えることにより、色調を変化させることが可能である。さらに、実施例２０のＢａＳｉ２Ｎ２Ｏ２：Ｅｕは、４９６ｎｍ近傍に発光ピーク波長を有し、高い発光効率を示す。実施例２０に係るオキシ窒化物蛍光体を使用することで、白色系発光装置の演色性の向上を図ることができる。
【０１７１】
＜実施例２１乃至２４＞
表４は、本発明に係るオキシ窒化物蛍光体の実施例２１乃至２４の特性を示す。
【０１７２】
また、図１８は、実施例２１乃至２４のオキシ窒化物蛍光体をＥｘ＝４００ｎｍで励起したときの発光スペクトルを示す図である。図１９は、実施例２１乃至２４のオキシ窒化物蛍光体をＥｘ＝４６０ｎｍで励起したときの発光スペクトルを示す図である。図２０は、実施例２１乃至２４のオキシ窒化物蛍光体の励起スペクトルを示す図である。図２１は、実施例２１乃至２４のオキシ窒化物蛍光体の反射スペクトルを示す図である。
【０１７３】
【表４】

【０１７４】
実施例２１乃至２４は、Ｃａ_ＸＢａ_{（１−Ｘ）}Ｓｉ_２Ｏ_２Ｎ_２：Ｅｕ（０≦Ｘ≦１）で表され、ＣａとＢａとのモル比を変えて製造を行っている。
【０１７５】
実施例２１乃至２４は、実施例１とほぼ同様の条件でオキシ窒化物蛍光体の製造を行った。原料は、Ｃａ_３Ｎ_２、Ｂａ_３Ｎ_２、Ｓｉ_３Ｎ_４、ＳｉＯ_２、Ｅｕ_２Ｏ_３を使用した。該原料を所定の数量に秤量した後、Ｃａ_３Ｎ_２、Ｂａ_３Ｎ_２、Ｓｉ_３Ｎ_４、ＳｉＯ_２、Ｅｕ_２Ｏ_３を、窒素雰囲気中、グローブボックス内で、均一になるまで混合した。実施例２１乃至２４において、Ｅｕ濃度は０．４３ｍｏｌ％である。
【０１７６】
上記化合物を混合し、アンモニア雰囲気中で、窒化ホウ素坩堝に投入し、約１４５０℃で約５時間、焼成を行った。
【０１７７】
これにより、目的とするオキシ窒化物蛍光体が製造された。
【０１７８】
実施例２１乃至２４は、発光輝度、量子効率は、実施例２１を基準として、相対値で表している。
【０１７９】
この結果から、４００ｎｍ近傍の光源で実施例２１乃至２４を励起させたとき、Ｃａ：Ｂａ＝４：６で混合させたときより、Ｃａ：Ｂａ＝８：２で混合させたときの方が、高い発光輝度、量子効率を示した。一方、４６０ｎｍ近傍の光源で実施例２１乃至２４を励起させたとき、Ｃａ：Ｂａ＝２：８で混合させたときより、Ｃａ：Ｂａ＝８：２で混合させたときの方が、高い発光輝度、量子効率を示した。また、ＣａとＢａのモル比を変えることにより、色調を変化させることが可能である。
【０１８０】
＜実施例２５乃至２７＞
実施例２５乃至２７のオキシナイトライド蛍光体について構造解析を行った。実施例２５の組成は、ＣａＳｉ_２Ｏ_２Ｎ_２である。実施例２６の組成は、ＳｒＳｉ_２Ｏ_２Ｎ_２である。実施例２７の組成は、ＢａＳｉ_２Ｏ_２Ｎ_２である。図２２は、斜方晶系を示す概略図である。図２３は、実施例２５のオキシナイトライド蛍光体のＸ線回折パターンを示す図である。図２４は、実施例２６のオキシナイトライド蛍光体のＸ線回折パターンを示す図である。図２５は、実施例２７のオキシナイトライド蛍光体のＸ線回折パターンを示す図である。
【０１８１】
この結果から、シリコンナイトライド系蛍光体の結晶の単位格子は、斜方晶系に帰属される。斜方晶系は、ａ≠ｂ≠ｃ、α＝β＝γ＝９０°であり、互いに垂直な２回対称軸三つ、あるいは２回対称軸と交わる二つの対称面を有する。
【０１８２】
＜発光装置＞
上述のオキシ窒化物蛍光体を用いて、実施例１の発光装置を製造した。励起光源として、４００ｎｍの発光スペクトルを有する発光素子を使用する。蛍光体は、実施例１のＣａＳｉ_２Ｏ_２Ｎ_２：Ｅｕと、Ｃａ_２Ｓｉ_５Ｎ_８：Ｅｕと、（Ｃａ_０．９３，Ｅｕ_０．０５，Ｍｎ_０．０２）_１０（ＰＯ_４）_６Ｃｌ_２を使用する。図１は、本発明に係る発光装置を示す。図２６は、本発明に係る発光素子を示す平面図である。図２７は、本発明に係る発光素子のＡ−Ａ‘を示す断面図である。図２８は、実施例１の発光装置の発光スペクトルを示す図である。図２９は、本発明に係る実施例１の発光装置の色度座標を示す図である。
【０１８３】
（発光素子）
サファイア（Ｃ面）よりなる基板２０１をＭＯＶＰＥの反応容器内にセットし、水素を流しながら、基板２０１の温度を約１０５０℃まで上昇させ、基板２０１のクリーニングを行う。
【０１８４】
ここで、本実施例では、基板２０１に、サファイア基板を用いているが、基板２０１として窒化物半導体と異なる異種基板、ＡｌＮ、ＡｌＧａＮ、ＧａＮ等の窒化物半導体基板を用いてもよい。異種基板としては、例えば、Ｃ面、Ｒ面及びＡ面のいずれかを主面とするサファイア、スピネル（ＭｇＡｌ_２Ｏ_４のような絶縁性基板、ＳｉＣ（６Ｈ、４Ｈ、３Ｃを含む）、ＺｎＳ、ＺｎＯ、ＧａＡｓ、Ｓｉ及び窒化物半導体と格子整合する酸化物基板等、窒化物半導体を成長させることが可能であり、窒化物半導体と異なる基板材料を用いることができる。好ましい異種基板としては、サファイア、スピネルが挙げられる。また、異種基板は、オフアングルしていてもよく、この場合、ステップ状にオフアングルしたものを用いると窒化ガリウムからなる下地層２０２の成長が結晶性よく成長するため好ましい。更に、異種基板を用いる場合には、異種基板上に素子構造形成前の下地層２０２となる窒化物半導体を成長させた後、異種基板を研磨などの方法により除去して、窒化物半導体の単体基板として素子構造を形成してもよく、また、素子構造形成後に、異種基板を除去する方法でも良い。ＧａＮ基板の他に、ＡｌＮ等の窒化物半導体の基板を用いても良い。
【０１８５】
（バッファ層）
続いて、基板２０１の温度を５１０℃まで下げ、キャリアガスに水素、原料ガスにアンモニアとＴＭＧ（トリメチルガリウム）とを用い、基板２０１上にＧａＮよりなるバッファ層（図示しない）を約１００オングストロームの膜厚で成長させる。
【０１８６】
（下地層）
バッファ層成長後、ＴＭＧのみ止めて、基板２０１の温度を１０５０℃まで上昇させる。１０５０℃になったら、同じく原料ガスにＴＭＧ、アンモニアガスを用い、アンドープＧａＮ層を２μｍの膜厚で成長させる。
【０１８７】
（ｎ型層）
続いて１０５０℃で、同じく原料ガスにＴＭＧ、アンモニアガス、不純物ガスにシランガスを用い、Ｓｉを４．５×１０^１８／ｃｍ^３ドープしたＧａＮよりなるｎ型層２０３を、ｎ型層としてｎ側電極２１１ａを形成するｎ側コンタクト層として、厚さ３μｍで成長させる。
【０１８８】
（活性層）
ＳｉドープＧａＮよりなる障壁層を５０オングストロームの膜厚で成長させ、続いて温度を８００℃にして、ＴＭＧ、ＴＭＩ、アンモニアを用いアンドープＩｎ_０．１Ｇａ_０．７Ｎよりなる井戸層を５０オングストロームの膜厚で成長させる。そして障壁＋井戸＋障壁＋井戸・・・＋障壁の順で障壁層を４層、井戸を３層、交互に積層して、総膜厚３５０オングストロームの多重量子井戸構造よりなる活性層２０４を成長させる。
【０１８９】
（ｐ側キャリア閉込め層）
次に、ＴＭＧ、ＴＭＡ、アンモニア、Ｃｐ_２Ｍｇ（シクロペンタジエニルマグネシウム）を用い、Ｍｇを５×１０^１９／ｃｍ^３ドープしたＡｌ_０．３Ｇａ_０．７Ｎよりなるｐ側キャリア閉込め層２０５を、膜厚１００オングストロームで成長させる。
【０１９０】
（第１ｐ型層）
続いて、ＴＭＧ、アンモニア、Ｃｐ_２Ｍｇを用い、ｐ型不純物をドープしたＧａＮよりなる第１ｐ型層２０６を、膜厚０．１μｍで成長させる。
【０１９１】
（第２ｐ型層）
第２ｐ型層として、表面にｐ側電極２１０を形成するｐ側コンタクト層２０８を形成する。ｐ側コンタクト層２０８は、電流拡散層２０７の上に、Ｍｇを１×１０^２０／ｃｍ^３ドープしたｐ型ＧａＮを１５０オングストロームの膜厚で成長させる。ｐ側コンタクト層２０８は、ｐ側電極２１０を形成する層であるので、１×１０^１７／ｃｍ^３以上の高キャリア濃度とすることが望ましい。１×１０^１７／ｃｍ^３よりも低いと電極と好ましいオーミックを得るのが難しくなる傾向にある。さらにコンタクト層の組成をＧａＮとすると、電極材料と好ましいオーミックが得られやすくなる。
【０１９２】
以上の素子構造を形成する反応を終了した後、温度を室温まで下げ、さらに窒素雰囲気中、ウェハーを反応容器内において、７００℃でアニーリングを行い、ｐ型層をさらに低抵抗化する。素子構造を形成したウェハーを装置から取り出し、以下に説明する電極形成工程を実施する。
【０１９３】
アニーリング後、ウェハーを反応容器から取り出し、最上層のｐ側コンタクト層２０８の表面に所定のマスクを形成し、ＲＩＥ（反応性イオンエッチング）装置でｐ側コンタクト層２０８側からエッチングを行い、ｎ側コンタクト層の表面を露出させて、電極形成面を形成する。
【０１９４】
ｐ側電極２１０として、Ｎｉ、Ａｕを順に積層して、Ｎｉ／Ａｕよりなるｐ側電極２１０を形成する。また、このｐ側電極２１０は、第２ｐ型層、ｐ側コンタクト層２０８にオーミック接触させたオーミック電極となる。このとき、形成された電極枝２１０ａは、ストライプ状の発光部２０９の幅を約５μｍ、ストライプ状の電極枝２１０ａの幅を約３μｍとし、ストライプ状の発光部２０９と電極枝２１０ａを交互に形成する。また、ｐ側パット電極が形成される領域には、ｐ側電極２１０を一部だけ形成し、ｐ側パット電極の上にわたって形成して、電気的に導通させる。このとき、ｐ側パット電極が形成される領域には、ｐ側電極２１０を一部だけ形成し、ｐ側パット電極２１０ｂを、ｐ側コンタクト層２０８の表面上に形成して、一部をｐ側電極２１０の上にわたって形成して、電気的に導通させる。このとき、ｐ側パット電極２１０ｂが設けられるｐ側コンタクト層２０８の表面は、ｐ側電極２１０とｐ側コンタクト層２０８とはオーミック接触させずに、ショットキー障壁が両者の間に形成されて、ｐ側パット電極２１０ｂの形成部からは、直接素子内部に電流が流れずに、電気的に接続された電極枝２１０ａを通って、電流を素子内部に注入する構造となる。
【０１９５】
続いて、ｎ型層２０３を露出させた露出面２０３ａに、ｎ側電極２１１ａを形成する。ｎ側電極２１１ａは、Ｔｉ、Ａｌを積層して形成する。
【０１９６】
ここで、ｎ側電極２１１ａは、ｎ型層２０３の露出面２０３ａにオーミック接触させたオーミック電極となる。オーミック用のｐ側電極２１０、ｎ側電極２１１ａを形成した後、熱処理でアニールして、各電極をオーミック接触させる。この時得られるｐ側のオーミック電極は、活性層２０４の発光をほぼ透過しない不透光性膜となる。
【０１９７】
続いて、上記ｐ側電極２１０、ｎ側電極２１１ａの一部、若しくは全部を除く表面全体に、すなわち、ｎ型層２０３の露出面２０３ａ及び該露出面２０３ａの側面などの素子表面全体に、ＳｉＯ_２よりなる絶縁膜を形成する。絶縁膜形成後、絶縁膜から露出したｐ側電極２１０、ｎ側電極２１１ａの表面に、それぞれボンディング用のパット電極を形成して、各オーミック用の電極に電気的に導通させる。ｐ側パット電極２１０ｂ、ｎ側パット電極２１１ｂは、各オーミック用の電極の上に、Ｎｉ、Ｔｉ、Ａｕを積層してそれぞれ形成する。
【０１９８】
最後に、基板２０１を分割して、一辺の長さが３００μｍの発光素子を得る。
【０１９９】
得られた発光素子は、発光ピーク波長が約４００ｎｍである。
【０２００】
実施例１の発光装置の特性を表５に示す。
【０２０１】
【表５】

【０２０２】
これより、実施例１の発光装置は、白色域に発光色を示す。実施例１の発光装置は、３６０〜４３０ｎｍ、４３０〜５００ｎｍ、５００〜７３０ｎｍに発光ピーク波長がある発光スペクトルを示している。より具体的には、３９０〜４１０ｎｍ、４５５〜４７５ｎｍ、５５０〜６００ｎｍに発光ピーク波長がある発光スペクトルを示す。４００ｎｍ励起の発光素子により励起された蛍光体は、実施例１のＣａＳｉ_２Ｏ_２Ｎ_２：Ｅｕは、緑色系領域に、Ｃａ_２Ｓｉ_５Ｎ_８：Ｅｕは、黄色から赤色系領域に、（Ｃａ_０．９３，Ｅｕ_０．０５，Ｍｎ_０．０２）_１０（ＰＯ_４）_６Ｃｌ_２は、青色系領域に、それぞれ発光ピーク波長を有する。これらの蛍光体の光の混色により、白色系領域に発光色を示す。これらの蛍光体の配合量を変更することにより、種々の色味の白色光を発する。従って、励起光源として、紫外光を用いて所定の白色光を有する発光装置を製造する場合、蛍光体の種類、配合比等を変更するだけで、発光色を変更することができる。
【０２０３】
＜発光装置＞
実施例２の発光装置は、励起光源に発光ピーク波長が４６０ｎｍの発光素子を用いた白色発光装置に関する。図１は、本発明に係る発光装置を示す図である。
【０２０４】
実施例２の発光装置は、サファイア基板１上にｎ型及びｐ型のＧａＮ層の半導体層２が形成され、該ｎ型及びｐ型の半導体層２に電極３が設けられ、該電極３は、導電性ワイヤ１４によりリードフレーム１３と導電接続されている。発光素子１０の上部は、蛍光体１１及びコーティング部材１２で覆われ、リードフレーム１３、蛍光体１１及びコーティング部材１２等の外周をモールド部材１５で覆っている。半導体層２は、サファイア基板１上にｎ^＋ＧａＮ：Ｓｉ、ｎ−ＡｌＧａＮ：Ｓｉ、ｎ−ＧａＮ、ＧａＩｎＮ ＱＷｓ、ｐ−ＧａＮ：Ｍｇ、ｐ−ＡｌＧａＮ：Ｍｇ、ｐ−ＧａＮ：Ｍｇの順に積層されている。該ｎ^＋ＧａＮ：Ｓｉ層の一部はエッチングされてｎ型電極が形成されている。該ｐ−ＧａＮ：Ｍｇ層上には、ｐ型電極が形成されている。リードフレーム１３は、鉄入り銅を用いる。マウントリード１３ａの上部には、発光素子１０を積載するためのカップが設けられており、該カップのほぼ中央部の底面に該発光素子１０がダイボンドされている。導電性ワイヤ１４には、金を用い、電極３と導電性ワイヤ１４を導電接続するためのバンプ４には、Ｎｉメッキを施す。蛍光体１１には、実施例４９の蛍光体とＹＡＧ系蛍光体とを混合する。コーティング部材１２には、エポキシ樹脂と拡散剤、チタン酸バリウム、酸化チタン及び前記蛍光体１１を所定の割合で混合したものを用いる。モールド部材１５は、エポキシ樹脂を用いる。この砲弾型の発光装置１は、モールド部材１５の半径２〜４ｍｍ、高さ約７〜１０ｍｍの上部が半球の円筒型である。
【０２０５】
実施例２の発光装置に電流を流すと、ほぼ４６０ｎｍに発光ピーク波長がある青色発光素子１０が発光する。この青色光を、半導体層２を覆う蛍光体１１が色調変換を行う。その結果、白色に発光する実施例２の発光装置を提供することができる。
【０２０６】
本発明に係る実施例２の発光装置の蛍光体１１は、実施例１のオキシ窒化物蛍光体と、ＣａＳｒＳｉ_５Ｎ_８：Ｅｕで表される窒化物蛍光体と、を混合した蛍光体１１を用いる。該蛍光体１１は、コーティング部材１２と一緒に混合されている。
【０２０７】
実施例２の発光装置は、発光素子１０の光の一部が透過する。また、発光素子１０の光の一部が蛍光体１１を励起し、該蛍光体１１は、波長変換を行い、オキシ窒化物蛍光体の緑色と、窒化物蛍光体の黄赤から赤色との光を発する。これらの発光素子１０からの青色光と、オキシ窒化物蛍光体からの緑色光と、窒化物蛍光体の黄赤から赤色光と、の光の混色により、白色に発光する発光装置を提供することができる。
【０２０８】
＜発光装置＞
図３０は、本発明に係るキャップタイプの発光装置を示す図である。
【０２０９】
実施例３の発光装置は、実施例１の発光装置における部材と同一の部材には同一の符号を付して、その説明を省略する。発光素子１０は、４００ｎｍに発光ピーク波長を有する発光素子を使用する。
【０２１０】
実施例３の発光装置は、実施例１の発光装置のモールド部材１５の表面に、蛍光体（図示しない）を分散させた光透過性樹脂からなるキャップ１６を被せることにより構成される。
【０２１１】
マウントリード１３ａの上部に、発光素子１０を積載するためのカップが設けられており、該カップのほぼ中央部の底面に該発光素子１０がダイボンドされている。実施例１の発光装置では、該カップの上部に発光素子１０を覆うように、蛍光体１１が設けられているが、実施例３の発光装置では、特に設けなくてもよい。該発光素子１０の上部に蛍光体１１を設けないことにより、発光素子１０から発生する熱の影響を直接受けないからである。
【０２１２】
キャップ１６は、蛍光体を光透過性樹脂に均一に分散させている。この蛍光体を含有する光透過性樹脂を、発光装置１のモールド部材１５の形状に嵌合する形状に成形している。または、所定の型枠内に蛍光体を含有する光透過性樹脂を入れた後、発光装置１を該型枠内に押し込み、成型する製造方法も可能である。キャップ１６の光透過性樹脂の具体的材料としては、エポキシ樹脂、ユリア樹脂、シリコーン樹脂などの温度特性、耐候性に優れた透明樹脂、シリカゾル、ガラス、無機バインダーなどが用いられる。上記の他、メラミン樹脂、フェノール樹脂等の熱硬化性樹脂を使用することができる。また、ポリエチレン、ポリプロピレン、ポリ塩化ビニル、ポリスチレン等の熱可塑性樹脂、スチレン−ブタジエンブロック共重合体、セグメント化ポリウレタン等の熱可塑性ゴム等も使用することができる。また、蛍光体と共に拡散剤、チタン酸バリウム、酸化チタン、酸化アルミニウムなどを含有させても良い。また、光安定化剤や着色剤を含有させても良い。キャップ１６に使用される蛍光体は、Ｃａ_２Ｓｉ_５Ｎ_８：Ｅｕの窒化物蛍光体と、（Ｃａ_０．９５，Ｅｕ_０．０５）_１０（ＰＯ_４）_６Ｃｌ_２の蛍光体とを使用する。マウントリード１３ａのカップ内に用いられる蛍光体１１は、実施例３のオキシ窒化物蛍光体を用いる。しかし、キャップ１６に蛍光体を用いるため、オキシ窒化物蛍光体をキャップ１６に含有し、マウントリード１３ａのカップ内は、コーティング部材１２のみでもよい。
【０２１３】
このように構成された発光装置は、発光素子１０から放出される光の一部は、蛍光体１１のオキシ窒化物蛍光体を励起し、緑色に発光する。また、発光素子１０から放出される光の一部、若しくはオキシ窒化物蛍光体から放出される光の一部がキャップ１６の蛍光体を励起し、青色と黄色から赤色に発光する。これにより、オキシ窒化物蛍光体の緑色光と、キャップ１６の蛍光体の青色と黄色から赤色光とが混合し、結果として、キャップ１６の表面からは、白色系の光が外部へ放出される。
【０２１４】
【発明の効果】
以上のことから、本発明は、近紫外から可視光の短波長側領域の励起光源と、該励起光源からの光により励起される、緑色から黄色系領域に発光色を示す蛍光体と、を少なくとも有する発光装置である。該発光装置は、鮮やかな発光色を示す。特に、紫外光を有する発光素子からの光により、オキシ窒化物蛍光体は、緑色から黄色系領域の発光色を示す。また、オキシ窒化物蛍光体の組成比を変えることにより、発光特性に優れた発光装置を提供することができる。また、発光効率の高い、再現性に優れた発光装置である。従って、本発明は、上述のような発光装置を提供することができるという極めて重要な技術的意義を有する。
【図面の簡単な説明】
【図１】 本発明に係る砲弾型の発光装置１を示す図である。
【図２】 （ａ）本発明に係る表面実装型の発光装置を示す平面図である。（ｂ）本発明に係る表面実装型の発光装置の断面図である。
【図３】 実施例１乃至５のオキシ窒化物蛍光体をＥｘ＝４００ｎｍで励起したときの発光スペクトルを示す図である。
【図４】 実施例１乃至５のオキシ窒化物蛍光体をＥｘ＝４６０ｎｍで励起したときの発光スペクトルを示す図である。
【図５】 実施例１乃至５のオキシ窒化物蛍光体の励起スペクトルを示す図である。
【図６】 実施例１乃至５のオキシ窒化物蛍光体の反射スペクトルを示す図である。
【図７】 実施例１のオキシ窒化物蛍光体を撮影したＳＥＭ写真である。
【図８】 実施例６乃至１０のオキシ窒化物蛍光体をＥｘ＝４００ｎｍで励起したときの発光スペクトルを示す図である。
【図９】 実施例６乃至１０のオキシ窒化物蛍光体をＥｘ＝４６０ｎｍで励起したときの発光スペクトルを示す図である。
【図１０】 実施例１１乃至１５のオキシ窒化物蛍光体をＥｘ＝４００ｎｍで励起したときの発光スペクトルを示す図である。
【図１１】 実施例１１乃至１５のオキシ窒化物蛍光体をＥｘ＝４６０ｎｍで励起したときの発光スペクトルを示す図である。
【図１２】 実施例１１乃至１５のオキシ窒化物蛍光体の励起スペクトルを示す図である。
【図１３】 実施例１１乃至１５のオキシ窒化物蛍光体の反射スペクトルを示す図である。
【図１４】 実施例１０、１６乃至２０のオキシ窒化物蛍光体をＥｘ＝４００ｎｍで励起したときの発光スペクトルを示す図である。
【図１５】 実施例１０、１６乃至２０のオキシ窒化物蛍光体をＥｘ＝４６０ｎｍで励起したときの発光スペクトルを示す図である。
【図１６】 実施例１０、１６乃至２０のオキシ窒化物蛍光体の励起スペクトルを示す図である。
【図１７】 実施例１０、１６乃至２０のオキシ窒化物蛍光体の反射スペクトルを示す図である。
【図１８】 実施例２１乃至２４のオキシ窒化物蛍光体をＥｘ＝４００ｎｍで励起したときの発光スペクトルを示す図である。
【図１９】 実施例２１乃至２４のオキシ窒化物蛍光体をＥｘ＝４６０ｎｍで励起したときの発光スペクトルを示す図である。
【図２０】 実施例２１乃至２４のオキシ窒化物蛍光体の励起スペクトルを示す図である。
【図２１】 実施例２１乃至２４のオキシ窒化物蛍光体の反射スペクトルを示す図である。
【図２２】 斜方晶系を示す概略図である。
【図２３】 実施例２５のオキシナイトライド蛍光体のＸ線回折パターンを示す図である。
【図２４】 実施例２６のオキシナイトライド蛍光体のＸ線回折パターンを示す図である。
【図２５】 実施例２７のオキシナイトライド蛍光体のＸ線回折パターンを示す図である。
【図２６】 本発明に係る発光素子を示す平面図である。
【図２７】 本発明に係る発光素子のＡ−Ａ‘を示す断面図である。
【図２８】 本発明に係る実施例１の発光装置の発光スペクトルを示す図である。
【図２９】 本発明に係る実施例１の発光装置の色度座標を示す図である。
【図３０】 本発明に係るキャップタイプの発光装置３を示す図である。
【符号の説明】
１ 基板
２ 半導体層
３ 電極
４ バンプ
１０ 発光素子
１１ 蛍光体
１２ コーティング部材
１３ リードフレーム
１３ａ マウントリード
１３ｂ インナーリード
１４ 導電性ワイヤ
１５ モールド部材
１０１ 発光素子
１０２ リード電極
１０３ 絶縁封止材
１０４ 導電性ワイヤ
１０５ パッケージ
１０６ リッド
１０７ 窓部
１０８ 蛍光体
１０９ コーティング部材
２０１ 基板
２０２ 下地層
２０３ ｎ型層
２０３ａ 露出面
２０４ 活性層
２０５ ｐ側キャリア閉込め層
２０６ 第１ｐ型層
２０７ 電流拡散層
２０８ ｐ側コンタクト層
２０９ 発光部
２１０ ｐ側電極
２１０ａ 電極枝
２１０ｂ ｐ側パット電極
２１１ａ ｎ側電極
２１１ｂ ｎ側パット電極[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a phosphor that emits light by being excited by electromagnetic waves such as light, electron beams, and X-rays, heat, and the like. . In particular, the present invention relates to white and multicolor light emitting devices using semiconductor light emitting elements.
[0002]
[Prior art]
A light-emitting device using a light-emitting element emits light of a bright color that is small and power efficient. In addition, since the light-emitting element is a semiconductor element, there is no fear of a broken ball. Further, it has excellent initial driving characteristics and is strong against vibration and repeated on / off lighting. Because of such excellent characteristics, light emitting devices using semiconductor light emitting elements such as LEDs and LDs are used as various light sources.
[0003]
A part or all of the light of the light emitting element is converted in wavelength by a phosphor, and the emission color different from the light of the light emitting element is emitted by mixing and emitting the wavelength converted light and the light of the light emitting element that is not wavelength converted. Light emitting devices that emit light have been developed.
[0004]
Among these light emitting devices, white light emitting devices are required in a wide range of fields such as lighting such as fluorescent lamps, in-vehicle lighting, displays, and backlights for liquid crystals. In addition, there are demands for light emitting devices of various colors such as pastel colors by combining a semiconductor light emitting element and a phosphor.
[0005]
The emission color of a light emitting device using a white semiconductor light emitting element is obtained by the principle of light color mixing. The blue light emitted from the light emitting element enters the phosphor layer, and after being repeatedly absorbed and scattered several times in the layer, is emitted to the outside. On the other hand, the blue light absorbed by the phosphor serves as an excitation light source and emits yellow fluorescence. This yellow light and blue light are mixed and appear as white to the human eye.
[0006]
For example, a blue light emitting element is used as the light emitting element, and a phosphor is thinly coded on the surface of the blue light emitting element. The light emitting element is a blue light emitting element using an InGaN-based material. The phosphor is (Y, Gd)₃(Al, Ga)₅O₁₂: YAG phosphor represented by the composition formula of Ce is used.
[0007]
In recent years, a white light emitting device using a light emitting element in the short wavelength side region of visible light and combining a phosphor emitting blue light and a YAG phosphor emitting yellow light has been reported. In this case, the YAG phosphor that emits yellow light is hardly excited by light in the short wavelength side region of visible light and does not emit light. For this reason, the blue phosphor is excited by the light emitting element to emit blue light. Next, the YAG phosphor is excited by the blue light and emits yellow light. Thus, white light is emitted by mixing the blue light of the blue phosphor and the yellow light of the YAG phosphor.
[0008]
Various phosphors have been developed for use in the light emitting device.
[0009]
For example, oxide phosphors using rare earth elements as the emission center have been widely known and some of them have been put into practical use. However, nitride phosphors and oxynitride phosphors have not been studied much, and only a few research reports have been made compared to oxide phosphors. For example, there is an oxynitride glass phosphor represented by Si—O—N, Mg—Si—O—N, Ca—Al—Si—O—N, or the like (see Patent Document 1). Further, there is an oxynitride glass phosphor represented by Ca—Al—Si—O—N activated with Eu (see Patent Document 2).
[0010]
[Patent Document 1]
JP 2001-214162 A
[Patent Document 2]
JP 2002-76434 A
[0011]
[Problems to be solved by the invention]
However, conventional phosphors have low emission luminance and are insufficient for use in light emitting devices. In a light emitting device using a light emitting element in the near-ultraviolet region, etc. as an excitation light source, the blue phosphor is excited by the light emitting element, and the YAG phosphor is excited by the excitation light. It is difficult to obtain white light. Therefore, there is a demand for a phosphor that is directly wavelength-converted by light in the short wavelength side region of visible light and emits green to yellow.
[0012]
In addition, as for a white light emitting device using a light emitting element in the short wavelength side region of visible light and a phosphor, an appropriate phosphor is not manufactured, and a light emitting device that can withstand practical use is not commercially available. Therefore, there is a demand for a phosphor that efficiently emits light in the short wavelength region of visible light.
[0013]
In addition, the oxynitride phosphors and the like disclosed in Patent Documents 1 and 2 have low emission luminance and are insufficient for use in a light emitting device. Moreover, since the phosphor of oxynitride glass is a glass body, it is generally difficult to process.
[0014]
Accordingly, an object of the present invention is to provide a light emitting device using a phosphor having a light emission color from green to yellow that is excited by an excitation light source in the near ultraviolet to visible light region and wavelength-converted. It is another object of the present invention to provide a light emitting device with high luminous efficiency and excellent reproducibility.
[0015]
[Means for Solving the Problems]
In order to solve the above-described problems, the present invention provides a light-emitting device that includes an excitation light source and a phosphor that converts the wavelength of at least part of light from the excitation light source. There is an emission peak wavelength in the red region, and it contains an oxynitride phosphor with crystals. The oxynitride phosphor has the general formula Sr _x Ca _1-x Si ₂ O ₂ N ₂ : Eu (0.3 ≦ x ≦ 0.7) and CaSi ₂ O ₂ N ₂ : Oxynitride phosphor having an emission peak wavelength shorter than Eu. Alternatively, the oxynitride phosphor is of the general formula Ca _x Ba _1-x Si ₂ O ₂ N ₂ : Represented by Eu (0.2 ≦ x ≦ 0.4)The present invention relates to a light emitting device. Thus, a light emitting device with high light emission efficiency can be provided. A yellow-based YAG-based phosphor having a light emission peak wavelength emits little light even when excited using non-myopic excitation light, but the oxynitride phosphor according to the present invention has a short wavelength from ultraviolet to visible light. It emits light by the excitation light in the side region and exhibits high luminous efficiency.
[0016]
Here, the short wavelength side region from ultraviolet to visible light is not particularly limited, but refers to a region of 240 to 500 nm or less. In particular, a range of 290 to 470 nm is preferable. More preferably, it is the range of 340-410 nm.
[0017]
The blue-green to yellow-red system region conforms to JIS Z8110. Specifically, the blue-green to yellow-red region refers to a range of 485 to 610 nm.
[0018]
  The oxynitride phosphor is, BeAnd at least one selected from the group consisting of C, Si, Ge, Sn, Ti, Zr, and Hf, and at least one group II element selected from the group consisting of Mg, Ca, Sr, Ba, and Zn A group IV element as described above;It consists of a crystal containing a rare earth element as activator R, and has an orthorhombic unit cellAn oxynitride phosphor is preferable. The oxynitride phosphor containing the above elements is excited by an excitation light source in the short wavelength side region of near ultraviolet to visible light, and absorbs a part of the light of the excitation light source. The excited and absorbed oxynitride phosphor performs wavelength conversion. The wavelength-converted light has an emission peak wavelength from green to yellow. As a result, the oxynitride phosphor absorbs part of the light from the light emitting element and has an emission spectrum having an emission peak wavelength in the green to yellow range. In addition, the oxynitride phosphor has high light emission efficiency, and can emit light from the light emitting element very efficiently. Furthermore, it is possible to provide a light emitting device that emits an intermediate color from the light emission color of the light emitting element to the light emission color of the oxynitride phosphor by mixing colors of light from the light emitting element and light of the oxynitride phosphor.
[0019]
The oxynitride phosphor preferably contains O and N in the composition, and the weight ratio of O to N is 1 to 0, and N is preferably 0.2 to 2.1. The molar ratio oxynitride phosphor is excited by light such as near ultraviolet, has a light emission peak wavelength from green to yellow, and exhibits high light emission efficiency.
[0020]
The oxynitride phosphor has a general formula: L_XM_YO_ZN_{((2/3) X + (4/3) Y- (2/3) Z)}: R or L_XM_YQ_TO_ZN_{((2/3) X + (4/3) Y + T- (2/3) Z)}: R (L is a Group II element that is at least one selected from the group consisting of Be, Mg, Ca, Sr, Ba, Zn. M is C, Si, Ge, Sn, Ti, Zr. , Hf is at least one group IV element selected from the group consisting of Hf, and Q is at least one group III element selected from the group consisting of B, Al, Ga, In. O is an oxygen element, N is a nitrogen element, R is a rare earth element, 0.5 <X <1.5, 1.5 <Y <2.5, 0 <T <0. 5, 1.5 <Z <2.5). The oxynitride phosphor is excited by excitation light in the short wavelength region from near ultraviolet to visible light, and has an emission peak wavelength from green to yellow. Further, the oxynitride phosphor has equal or higher stability than the YAG phosphor. Furthermore, since the oxynitride phosphor is not a glass body (amorphous) and the light emitting part is a crystalline powder or granule, it is easy to manufacture and process. By setting the X, Y, T, and Z within the above ranges, a phosphor with good luminous efficiency can be provided. That is, within the above range, a crystal layer having substantially light emitting properties is formed. On the other hand, when it is out of the above range, the light emission efficiency is lowered.
[0021]
X, Y, and Z are preferably X = 1, Y = 2, and Z = 2. This is because at the time of the composition, crystallinity is improved and luminous efficiency is increased.
[0022]
70% by weight or more of R is preferably Eu. The rare earth element R is preferably Eu since it has high luminous efficiency. This is because high luminous efficiency can be obtained by using the Eu amount within this range.
[0023]
The oxynitride phosphor relates to an oxynitride phosphor characterized in that at least a part thereof has a crystal. Particularly preferably, the oxynitride phosphor has at least 50% by weight, more preferably 80% by weight or more of crystals. This indicates the ratio of the crystal phase having luminescence, and it is preferable to have 50% by weight or more of the crystal phase because light emission that can withstand practical use can be obtained. Therefore, the more crystal phases, the better. Thereby, the light emission luminance can be increased, and the manufacture and processing of the oxynitride phosphor can be facilitated.
[0024]
The crystal has an orthorhombic unit cell. When the crystal structure is analyzed from the X-ray diffraction pattern of the phosphor, the unit cell of the crystal belongs to the orthorhombic system.
[0025]
The oxynitride phosphor preferably has an excitation spectrum having a higher intensity at 370 nm than at 500 nm. Thereby, the ultraviolet region shows higher luminance than the blue region. That is, higher light emission efficiency can be exhibited by using the light emitting element in the ultraviolet region than using the light emitting element in the blue region.
[0026]
The oxynitride phosphor preferably has a certain Group II element selected from the group consisting of at least two types of Be, Mg, Ca, Sr, Ba, and Zn. This is because light emission characteristics such as color tone, light emission luminance, and quantum efficiency can be changed.
[0027]
  The oxynitride phosphor has Sr and Ca, and the molar ratio of Sr and Ca is larger than Sr: Ca = 0: 10 and smaller than 10: 0, more preferably 3: 7. It is preferably from 9: 1. The oxynitride phosphor has Sr and Ba, and the molar ratio of Sr and Ba is Sr: Ba = 5: 5 or more and smaller than 10: 0, more preferably 6: 4. It is preferably from 9: 1. The oxynitride phosphor has Ca and Ba, and the molar ratio of Ca to Ba is larger than Ca: Ba = 0: 10 and smaller than 10: 0, more preferably 1. : 9 to 9: 1 is preferable. Oxynitride phosphors of various colors can be manufactured by a predetermined combination. In addition, by setting this range, it is possible to improve the light emission efficiency.
[0028]
The excitation light source relates to a light emitting device having at least one emission peak wavelength in a short wavelength side region from ultraviolet to visible light. This is because a phosphor with high luminous efficiency can be provided by using an excitation light source in this range. In particular, it is preferable to use an excitation light source having an emission peak wavelength at 240 to 470 nm, and it is preferable to use an excitation light source having an emission peak wavelength at 350 to 410 nm.
[0029]
The excitation light source is preferably a light emitting element. The light emitting element is small in size, has high power efficiency, and emits bright colors. In addition, since the light-emitting element is a semiconductor element, there is no fear of a broken ball. Further, it has excellent initial driving characteristics and is strong against vibration and repeated on / off lighting. Therefore, a light-emitting device that combines a light-emitting element and an oxynitride phosphor is preferable.
[0030]
The light emitting layer of the light emitting element preferably includes a nitride semiconductor containing In. Thereby, the light emitting element emits light having an emission peak wavelength in the vicinity of 350 to 410 nm, and the oxynitride phosphor is excited by the light from the light emitting element, and exhibits a predetermined emission color. This is because the oxynitride phosphor strongly emits light in the vicinity of 350 to 410 nm, and thus a light emitting element in this wavelength region is required. In addition, since the emission spectrum width can be narrowed, the oxynitride phosphor can be excited efficiently, and the emission spectrum that does not substantially affect the color tone change from the light emitting device. Can be released.
[0031]
The phosphor includes a second phosphor used together with the oxynitride phosphor, and the second phosphor includes light from the excitation light source and light from the oxynitride phosphor. The present invention relates to a light-emitting device characterized in that at least a part of is converted into a wavelength and has an emission peak wavelength in the visible light region. Thus, a light emitting device having a light emission color in the visible light region can be provided by mixing the light from the excitation light source, the light of the oxynitride phosphor, and the light of the second phosphor. The light emitting device can emit a desired light emission color in a wavelength range from the emission color of the excitation light source to the emission color of the oxynitride phosphor or the emission color of the second phosphor.
[0032]
The second phosphor relates to a light emitting device having at least one emission peak wavelength from a blue region to a green, yellow, and red region. This is because the light emitting device can exhibit a desired emission color. In particular, by combining the three primary colors of the green color of the oxynitride phosphor excited by an excitation light source having an emission peak wavelength in the short wavelength region from ultraviolet to visible light, the blue color of the second phosphor, and the red color, This is because various emission colors can be realized. However, the light emitting device may be a combination of two kinds of colors such as green and red and green and yellow.
[0033]
The second phosphors are alkaline earth halogen apatite phosphors, alkaline earth metal borate phosphors, alkaline earths mainly activated by lanthanoids such as Eu and transition metal elements such as Mn. Mainly activated by lanthanoid elements such as metal aluminate phosphors, alkaline earth silicates, alkaline earth sulfides, alkaline earth thiogallate, alkaline earth silicon nitride, germanate, or Ce It is preferably at least one selected from a rare earth aluminate, a rare earth silicate, or an organic or organic complex mainly activated by a lanthanoid element such as Eu. This is because it is possible to provide a light emitting device having high light emission efficiency such as light emission luminance and quantum efficiency. In addition, a light-emitting device with favorable color rendering properties can be provided. However, the second phosphor is not limited to the above, and phosphors that emit light in various colors can be used.
[0034]
The light emitting device emits a mixture of at least two of the light from the excitation light source, the light from the oxynitride phosphor, and the light from the second phosphor. It is preferred that Thereby, the emission color of the light emitting device can be adjusted, and a desired emission color can be emitted. In particular, when a light emitting element that emits light in the ultraviolet region is used, the human eye can hardly see the emission color in the ultraviolet region. Therefore, the color of light emitted by mixing the light from the oxynitride phosphor and the light from the second phosphor is shown. Since the luminescent color is determined only by the phosphor, the luminescent color can be easily adjusted. Here, although expressed as the second phosphor, the second phosphor is not limited to one type, and several types of phosphors may be included. This is because by including several kinds of phosphors, more delicate chromaticity adjustment is possible. In particular, when a light-emitting element having a short wavelength region such as ultraviolet light or visible light is used, light from the light-emitting element is less likely to be perceived by human eyes, and thus there is little chromaticity shift due to manufacturing variations.
[0035]
The light emitting device may have an intermediate emission color from an emission peak wavelength of the excitation light source to an emission peak wavelength of the oxynitride phosphor or an emission peak wavelength of the second phosphor. The emission spectrum of the excitation light source is on the shorter wavelength side than the oxynitride phosphor or the second phosphor, and has high energy. The emission color from this high energy region to the low energy region of the oxynitride phosphor and the second phosphor can be emitted. In particular, the emission color from the emission peak wavelength of the light emitting element to the first emission peak wavelength of the oxynitride phosphor or the second emission peak wavelength of the second phosphor is shown. For example, when the emission peak wavelength of the light emitting element is in the blue region, the emission peak wavelength of the excited first phosphor is green, and the emission peak wavelength of the excited second phosphor is red, 3 It is possible to show a white emission color by mixing colors. As a different example, the emission peak wavelength of the light emitting element is in the ultraviolet region, the emission peak wavelength of the excited first phosphor is green, and the emission peak wavelength of the excited second phosphor is yellow and red. In some cases, it is possible to show slightly yellowish white and multicolored emission colors. By changing the blending amount of the oxynitride phosphor and the second phosphor, light emission from a color close to the emission color of the oxynitride phosphor to a color close to the emission color of the second phosphor Can show the color. Further, when the second phosphor has two or more emission peak wavelengths, the emission peak wavelength of the excitation light source, the emission peak wavelength of the oxynitride phosphor, and two or more of the second phosphor have It is a light-emitting device which shows the luminescent color between the light emission peak wavelengths. The second phosphor can be used not only in one type but also in combination of two or more types. In addition to light emitting devices that emit white light, there is also a need for light emitting devices that emit light in various colors such as pastel colors. A light-emitting device having a desired color can be provided by variously combining a green-based oxynitride phosphor, a red-based phosphor, and a blue-based phosphor. Light emitting devices with different colors are not only a method of changing the type of phosphor, but also a method of changing the blending ratio of the phosphors to be combined, a method of changing the coating method of applying the phosphor to the excitation light source, There is a method to adjust the lighting time of.
[0036]
The intermediate emission color preferably emits white light. In particular, it is preferable to emit white light near the locus of blackbody radiation. This is because it can be used for various purposes such as illumination, a liquid crystal backlight, and a display.
[0037]
The light-emitting device is preferably a light-emitting device having an emission spectrum having at least one emission peak wavelength at 430 to 500 nm and 500 to 730 nm. A light emitting device that emits light in a desired color can be provided by combining blue light, green light, red light, and the like. For this reason, color rendering properties can be improved by combining several phosphors. Even with the same white light emission, there are whites that are yellowish and whites that are bluish. Therefore, it has an emission spectrum with an emission peak wavelength in the above range.
As described above, the light-emitting device according to the present invention has the technical significance that it can provide a light-emitting device using an oxynitride phosphor that is excited by a light-emitting element in the near ultraviolet to visible light region and wavelength-converted. Have. The oxynitride phosphor has a high luminous efficiency, is a stable and highly reproducible phosphor. Further, it has a technical significance that a light emitting device having a desired emission color can be provided by combining a light emitting element, an oxynitride phosphor, and a second phosphor.
[0038]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a light-emitting device according to the present invention, an oxynitride phosphor used in the light-emitting device, and a manufacturing method thereof will be described using embodiments and examples. However, the present invention is not limited to this embodiment and example.
[0039]
The light emitting device according to the present invention is a light emitting device having at least a light emitting element and a first phosphor that converts the wavelength of at least part of light from the light emitting element. An example of a specific light-emitting device will be described with reference to FIG. FIG. 1 is a diagram showing a light emitting device according to the present invention. Here, JIS Z8110 is taken into consideration for the relationship between color names and chromaticity coordinates.
[0040]
(Excitation light source)
As the excitation light source, one having an emission peak wavelength from the near ultraviolet to the short wavelength side of visible light is used. Any excitation light source having an emission peak wavelength in this range is not particularly limited. Examples of the excitation light source include a lamp and a semiconductor light emitting element, and it is preferable to use a semiconductor light emitting element.
[0041]
(Light emitting device)
The light emitting device according to the first embodiment includes a semiconductor layer 2 stacked on the top of a sapphire substrate 1, and a lead frame 13 conductively connected by a conductive wire 14 extending from positive and negative electrodes 3 formed on the semiconductor layer 2. The phosphor 11 and the coating member 12 provided in the cup of the lead frame 13a so as to cover the outer periphery of the light emitting element 10 composed of the sapphire substrate 1 and the semiconductor layer 2, the phosphor 11 and the lead And a mold member 15 that covers the outer peripheral surface of the frame 13.
[0042]
A semiconductor layer 2 is formed on the sapphire substrate 1, and positive and negative electrodes 3 are formed on the same plane side of the semiconductor layer 2. The semiconductor layer 2 is provided with a light emitting layer (not shown), and an emission peak wavelength output from the light emitting layer has an emission spectrum in the vicinity of 500 nm or less in the ultraviolet to blue region.
[0043]
The light-emitting element 10 is set on a die bonder, face-up to a lead frame 13a provided with a cup, and die-bonded (adhered). After die bonding, the lead frame 13 is transferred to a wire bonder, the negative electrode 3 of the light emitting element is wire bonded to the lead frame 13a provided with a cup with a gold wire, and the positive electrode 3 is wire bonded to the other lead frame 13b. .
[0044]
Next, it transfers to a molding apparatus and inject | pours the fluorescent substance 11 and the coating member 12 in the cup of the lead frame 13 with the dispenser of a molding apparatus. The phosphor 11 and the coating member 12 are uniformly mixed in advance at a desired ratio.
[0045]
After the phosphor 11 is injected, the lead frame 13 is immersed in a mold mold in which a mold member 15 has been injected in advance, and then the mold is removed to cure the resin, and a bullet-type light emitting device as shown in FIG. To do.
[0046]
(Light emitting device)
A specific configuration of the light emitting device of the second embodiment different from the light emitting device of the first embodiment will be described in detail. FIG. 2 is a diagram showing a light emitting device according to the present invention. The light-emitting device of Embodiment 2 forms a surface-mount type light-emitting device. As the light-emitting element 101, an ultraviolet-excited nitride semiconductor light-emitting element can be used. The light-emitting element 101 can also be a blue-light-excited nitride semiconductor light-emitting element. Here, the light emitting element 101 excited by ultraviolet light will be described as an example. The light emitting element 101 uses a nitride semiconductor light emitting element having an InGaN semiconductor with an emission peak wavelength of about 370 nm as a light emitting layer. As a more specific LED element structure, an n-type GaN layer that is an undoped nitride semiconductor on a sapphire substrate, a GaN layer that is formed with an Si-doped n-type electrode and becomes an n-type contact layer, and an undoped nitride semiconductor A single quantum well structure includes an n-type GaN layer, an n-type AlGaN layer that is a nitride semiconductor, and then an InGaN layer that constitutes a light-emitting layer. On the light emitting layer, an AlGaN layer as a p-type cladding layer doped with Mg and a GaN layer as a p-type contact layer doped with Mg are sequentially laminated. (Note that a GaN layer is formed on the sapphire substrate at a low temperature to serve as a buffer layer. In addition, the p-type semiconductor is annealed at 400 ° C. or higher after film formation). Etching exposes the surface of each pn contact layer on the same side as the nitride semiconductor on the sapphire substrate. An n-electrode is formed in a strip shape on the exposed n-type contact layer, and a translucent p-electrode made of a metal thin film is formed on almost the entire surface of the p-type contact layer that remains without being cut. A pedestal electrode is formed on the p-electrode in parallel with the n-electrode using a sputtering method.
[0047]
Next, a Kovar package 105 having a concave portion at the center and a base portion into which Kovar lead electrodes 102 are inserted and fixed in an airtight manner on both sides of the concave portion is used. A Ni / Ag layer is provided on the surface of the package 105 and the lead electrode 102. The light emitting element 101 described above is die-bonded with an Ag—Sn alloy in the recess of the package 105. With this configuration, all components of the light-emitting device can be made of an inorganic material, and the reliability of the light-emitting device can be dramatically improved even if the light emitted from the light-emitting element 101 is in the ultraviolet region or the short wavelength region of visible light. A light emitting device with high brightness is obtained.
[0048]
Next, each electrode of the die-bonded light emitting element 101 and each lead electrode 102 exposed from the bottom of the package recess are electrically connected by an Ag wire 104. After sufficiently removing moisture in the recess of the package, sealing is performed with a Kovar lid 106 having a glass window 107 at the center, and seam welding is performed. In the glass window portion, CaSi is preliminarily applied to a slurry of 90 wt% nitrocellulose and 10 wt% γ-alumina.₂O₂N₂: Eu, (Y_0.8Gd_0.2)₃Al₅O₁₂: A phosphor 108 such as Ce is contained, applied to the back surface of the translucent window 107 of the lid 106, and heat-cured at 220 ° C. for 30 minutes to constitute a color conversion member. When the light emitting device thus formed emits light, a light emitting diode capable of emitting white light with high luminance can be obtained. As a result, it is possible to obtain a light emitting device that is extremely easy to adjust chromaticity and has excellent mass productivity and reliability. Hereafter, each structure of this invention is explained in full detail.
[0049]
Hereinafter, constituent members of the light emitting device according to the present invention will be described in detail.
[0050]
(Phosphor 11, 108)
The phosphors 11 and 108 include oxynitride phosphors. In addition, the phosphors 11 and 108 may be a combination of an oxynitride phosphor and a second phosphor. The oxynitride phosphor according to the present invention uses a rare earth element as an activator, and includes at least one group II element selected from the group consisting of Be, Mg, Ca, Sr, Ba, and Zn, And at least one group IV element selected from the group consisting of C, Si, Ge, Sn, Ti, Zr, and Hf. Although the combination of these elements is arbitrary, it is preferable to use the following composition. The oxynitride phosphor is L_XM_YO_ZN_{((2/3) X + (4/3) Y- (2/3) Z)}: R or L_XM_YQ_TO_ZN_{((2/3) X + (4/3) Y + T- (2/3) Z)}: R (L is a Group II element that is at least one selected from the group consisting of Be, Mg, Ca, Sr, Ba, Zn. M is C, Si, Ge, Sn, Ti, Zr. , Hf is at least one group IV element selected from the group consisting of Hf, and Q is at least one group III element selected from the group consisting of B, Al, Ga, In. O is an oxygen element, N is a nitrogen element, R is a rare earth element, 0.5 <X <1.5, 1.5 <Y <2.5, 0 <T <0. 5, 1.5 <Z <2.5)). Said X, said Y, and said Z show a high brightness | luminance in this range. Of these, oxynitride phosphors in which X, Y, and Z are represented by X = 1, Y = 2, and Z = 2 in the general formula are particularly preferable because they exhibit high luminance. However, it is not limited to the said range, Arbitrary things can also be used. Specifically, CaSi₂O₂N₂: Eu, SrSi₂O₂N₂: Eu, BaSi₂O₂N₂: Eu, ZnSi₂O₂N₂: Eu, CaGe₂O₂N₂: Eu, SrGe₂O₂N₂: Eu, BaGe₂O₂N₂: Eu, ZnGe₂O₂N₂: Eu, Ca_0.5Sr_0.5Si₂O₂N₂: Eu, Ca_0.5Ba_0.5Si₂O₂N₂: Eu, Ca_0.5Zn_0.5Si₂O₂N₂: Eu, Ca_0.5Be_0.5Si₂O₂N₂: Eu, Sr_0.5Ba_0.5Si₂O₂N₂: Eu, Ca_0.8Mg_0.2Si₂O₂N₂: Eu, Sr_0.8Mg_0.2Si₂O₂N₂: Eu, Ca_0.5Mg_0.5Si₂O₂N₂: Eu, Sr_0.5Mg_0.5Si₂O₂N₂: Eu, CaSi₂B_0.1O₂N₂: Eu, SrSi₂B_0.1O₂N₂: Eu, BaSi₂B_0.1O₂N₂: Eu, ZnSi₂B_0.1O₂N₂: Eu, CaGe₂B_0.01O₂N₂: Eu, SrGe₂Ga_0.01O₂N₂: Eu, BaGe₂In_0.01O₂N₂: Eu, ZnGe₂Al_0.05O₂N₂: Eu, Ca_0.5Sr_0.5Si₂B_0.3O₂N₂: Eu, CaSi_2.5O_1.5N₃: Eu, SrSi_2.5O_1.5N₃: Eu, BaSi_2.5O_1.5N₃: Eu, Ca_0.5Ba_0.5Si_2.5O_1.5N₃: Eu, Ca_0.5Sr_0.5Si_2.5O_1.5N₃: Eu, Ca_1.5Si_2.5O_2.5N_2.7: Eu, Sr_1.5Si_2.5O_2.5N_2.7: Eu, Ba_1.5Si_2.5O_2.5N_2.7: Eu, Ca_1.0Ba_0.5Si_2.5O_1.5N₃: Eu, Ca_1.0Sr_0.5Si_2.5O_1.5N₃: Eu, Ca_0.5Si_1.5O_1.5N_1.7: Eu, Sr_0.5Si_1.5O_1.5N_1.7: Eu, Ba_0.5Si_1.5O_1.5N_1.7: Eu, Ca_0.3Ba_0.2Si_2.5O_1.5N₃: Eu, Ca_0.2Sr_0.3Si_2.5O_1.5N₃: An oxynitride phosphor represented by Eu or the like can be used. Moreover, as shown here, this oxynitride phosphor can adjust a color tone and a brightness | luminance by changing the ratio of O and N. FIG. It is also possible to finely adjust the emission spectrum and intensity by changing the molar ratio of the cation and the anion represented by (L + M) / (O + N). This is possible by, for example, performing a process such as a vacuum to desorb N and O, but is not limited to this method. The composition of the oxynitride phosphor may contain at least one of Li, Na, K, Rb, Cs, Mn, Re, Cu, Ag, and Au. This is because the luminous efficiency such as luminance and quantum efficiency can be adjusted by adding them. Further, other elements may be included so as not to impair the characteristics. However, the present invention is not limited to this embodiment and examples.
[0051]
L is a Group II element that is at least one selected from the group consisting of Mg, Ca, Sr, Ba, and Zn. That is, Ca, Sr or the like may be used alone, but various combinations such as Ca and Sr, Ca and Ba, Sr and Ba, Ca and Mg, and the like can be changed. The mixing ratio of the mixture of Sr and Ca can be changed as desired.
[0052]
M is a Group IV element that is at least one selected from the group consisting of C, Si, Ge, Sn, Ti, and Hf. As M, Si, Ge or the like may be used alone, but various combinations such as Si and Ge, Si and C, etc. can be changed. Although this element can be used, it is particularly preferable to use Si or Ge. This is because it is possible to provide an inexpensive phosphor with good crystallinity.
[0053]
R is a rare earth element. Specifically, R is La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lr. Of these rare earth elements, Eu is preferable. Moreover, what contains Eu and at least 1 or more elements chosen from rare earth elements can also be used. R preferably contains 70% or more of Eu.
[0054]
Europium Eu, which is a rare earth element, is used for the emission center. Although the present invention will be described using Eu, the present invention is not limited to this. Europium mainly has bivalent and trivalent energy levels. The phosphor of the present invention has Eu as a base material for alkaline earth metal silicon nitride.²⁺Is used as an activator. Eu²⁺Is easily oxidized and generally trivalent Eu₂O₃It is marketed with the composition.
[0055]
As the base material, each of the main components L and M can also be used. For these main components L and M, metals, oxides, imides, amides, nitrides and various salts can be used. In addition, the main components L and M may be mixed and used in advance.
[0056]
Q is a Group III element that is at least one selected from the group consisting of B, Al, Ga, and In. As Q, metals, oxides, imides, amides, nitrides, various salts, and the like can be used. For example, B₂O₆, H₃BO₃, Al₂O₃, Al (NO₃)₃・ 9H₂O, AlN, GaCl₃, InCl₃Etc.
[0057]
L nitride, M nitride, and M oxide are mixed as a base material. In the base material, Eu oxide is mixed as an activator. Weigh these in the desired amount and mix until uniform. In particular, the base material L nitride, M nitride, and M oxide are 0.5 <L nitride <1.5, 0.25 <M nitride <1.75,2. It is preferred that the oxides are mixed in a molar ratio of 25 <M oxide <3.75. These matrix materials are_XM_YO_ZN_{((2/3) X + Y- (2/3) Z-α)}: R or L_XM_YQ_TO_ZN_{((2/3) X + Y + T- (2/3) Z-α)}: A predetermined amount is weighed and mixed so that the composition ratio of R is obtained.
[0058]
(Method for producing oxynitride phosphor)
Next, the oxynitride phosphor according to the present invention, CaSi₂O₂N₂: Although the manufacturing method of Eu is demonstrated, it is not limited to this manufacturing method.
[0059]
First, Ca nitride, Si nitride, Si oxide, and Eu oxide are mixed so as to obtain a predetermined blending ratio.
[0060]
A Ca nitride, Si nitride, Si oxide, and Eu oxide are prepared in advance. It is better to use purified materials, but commercially available materials may be used. Specifically, raw material Ca is pulverized. The raw material Ca is preferably a simple substance, but compounds such as imide compounds, amide compounds, and CaO can also be used. The raw material Ca may contain B, Ga, or the like. The raw material Ca is pulverized in a glove box in an argon atmosphere. Ca obtained by pulverization preferably has an average particle diameter of about 0.1 μm to 15 μm, but is not limited to this range. The purity of Ca is preferably 2N or higher, but is not limited thereto.
[0061]
The raw material Ca is nitrided in a nitrogen atmosphere. This reaction formula is shown in Chemical Formula 1.
[0062]
[Chemical 1]
3Ca + N₂  → Ca₃N₂
Ca can be nitrided in a nitrogen atmosphere at 600 to 900 ° C. for about 5 hours to obtain a nitride of Ca. The Ca nitride is preferably of high purity, but commercially available products can also be used.
[0063]
Crush the nitride of Ca. Ca nitride is pulverized in a glove box in an argon atmosphere or a nitrogen atmosphere.
[0064]
The raw material Si is pulverized. The raw material Si is preferably a simple substance, but a nitride compound, an imide compound, an amide compound, or the like can also be used. For example, Si₃N₄, Si (NH₂)₂, Mg₂Si, Ca₂Si, SiC and the like. The purity of the raw material Si is preferably 3N or higher, but may contain B, Ga and the like. Si is also pulverized in a glove box in an argon atmosphere or a nitrogen atmosphere in the same manner as the raw material Ca. The average particle size of the Si compound is preferably about 0.1 μm to 15 μm.
[0065]
The raw material Si is nitrided in a nitrogen atmosphere. This reaction formula is shown in Chemical Formula 2.
[0066]
[Chemical 2]
3Si + 2N₂  → Si₃N₄
Silicon Si is also nitrided in a nitrogen atmosphere at 800 to 1200 ° C. for about 5 hours to obtain silicon nitride. The silicon nitride used in the present invention is preferably highly pure, but commercially available ones can also be used.
[0067]
Similarly, Si nitride is pulverized.
[0068]
SiO, an oxide of Si₂Is a commercially available product (silicon dioxide 99.9%, 190-09072, manufactured by Wako Pure Chemical Industries, Ltd.).
[0069]
A predetermined molar amount of the raw material purified or manufactured as described above is weighed. The weighed raw materials are mixed.
[0070]
Next, a mixture of Ca nitride, Si nitride, Si oxide, and Eu oxide is baked at about 1500 ° C. in an ammonia atmosphere. The mixture is put into a crucible and fired.
[0071]
By mixing and firing, CaSi₂O₂N₂: An oxynitride phosphor represented by Eu can be obtained. The reaction formula of basic constituent elements by this firing is shown in Chemical Formula 3.
[0072]
[Chemical Formula 3]

[0073]
However, this composition is a representative composition estimated from the blending ratio, and has sufficient characteristics to withstand practical use in the vicinity of the ratio. Moreover, the composition of the target phosphor can be changed by changing the blending ratio of each raw material.
[0074]
For firing, a tubular furnace, a small furnace, a high-frequency furnace, a metal furnace, or the like can be used. The firing temperature is not particularly limited, but the firing is preferably performed in the range of 1200 to 1700 ° C, more preferably 1400 to 1700 ° C. The raw material of the phosphor 11 is preferably fired using a crucible or boat made of boron nitride (BN). In addition to crucible made of boron nitride, alumina (Al₂O₃) Material crucibles can also be used.
[0075]
The reducing atmosphere is a nitrogen atmosphere, a nitrogen-hydrogen atmosphere, an ammonia atmosphere, an inert gas atmosphere such as argon, or the like.
[0076]
By using the above manufacturing method, it is possible to obtain a target oxynitride phosphor.
[0077]
Ca_XSi_YB_TO_ZN_{((2/3) X + Y + T- (2/3) Z-α)}: The oxynitride phosphor represented by Eu can be manufactured as follows.
[0078]
In advance, Eu compound is added to Eu compound B.₃BO₃Is dry mixed. Europium oxide is used as the Eu compound, but metal europium, europium nitride, and the like can be used as in the other constituent elements described above. In addition, an imide compound or an amide compound can also be used as the raw material Eu. Europium oxide is preferably highly purified, but commercially available products can also be used. The compound of B is dry mixed, but can also be wet mixed. Since some of these mixtures are easily oxidized, they are mixed in a glove box in an Ar atmosphere or a nitrogen atmosphere.
[0079]
Compound H of B₃BO₃As an example, a method for producing an oxynitride phosphor will be described. The component constituent elements other than B include Li, Na, K and the like, and these compounds, for example, LiOH.H₂O, Na₂CO₃, K₂CO₃, RbCl, CsCl, Mg (NO₃)₂, CaCl₂・ 6H₂O, SrCl₂・ 6H₂O, BaCl₂・ 2H₂O, TiOSO₄・ H₂O, ZrO (NO₃)₂, HfCl₄, MnO₂, ReCl₅, Cu (CH₃COO)₂・ H₂O, AgNO₃, HAuCl₄・ 4H₂O, Zn (NO₃)₂・ 6H₂O, GeO₂, Sn (CH₃COO)₂Etc. can be used.
[0080]
Grind the mixture of Eu and B. The average particle size of the mixture of Eu and B after pulverization is preferably about 0.1 μm to 15 μm.
[0081]
After the pulverization, the aforementioned CaSi₂O₂N₂: Almost similar to the Eu manufacturing process, Ca nitride, Si nitride, Si oxide, and Eu oxide containing B are mixed. After the mixing, firing is performed to obtain the target oxynitride phosphor.
[0082]
(Second phosphor 11, 108)
The phosphors 11 and 108 include the second phosphor together with the oxynitride phosphor. Examples of the second phosphor include alkaline earth halogen apatite phosphors, alkaline earth metal borate phosphors, alkaline earths mainly activated by lanthanoid compounds such as Eu, and transition metal elements such as Mn. Mainly activated by metal aluminate phosphor, alkaline earth silicate, alkaline earth sulfide, alkaline earth thiogallate, alkaline earth silicon nitride, germanate, or lanthanoid elements such as Ce It is preferably at least one selected from a rare earth aluminate, a rare earth silicate, or an organic or organic complex mainly activated by a lanthanoid element such as Eu. As specific examples, the following phosphors can be used, but are not limited thereto.
[0083]
Alkaline earth halogen apatite phosphors mainly activated by lanthanoid compounds such as Eu and transition metal elements such as Mn include M₅(PO₄)₃X: R (M is at least one selected from Sr, Ca, Ba, Mg, Zn. X is at least one selected from F, Cl, Br, I. R is Eu. , Mn, or any one of Eu and Mn).
[0084]
Alkaline earth metal halogen borate phosphors include M₂B₅O₉X: R (M is at least one selected from Sr, Ca, Ba, Mg, Zn. X is at least one selected from F, Cl, Br, I. R is Eu. , Mn, or any one of Eu and Mn).
[0085]
For alkaline earth metal aluminate phosphors, SrAl₂O₄: R, Sr₄Al₁₄O₂₅: R, CaAl₂O₄: R, BaMg₂Al₁₆O₂₇: R, BaMg₂Al₁₆O₁₂: R, BaMgAl₁₀O₁₇: R (R is one or more of Eu, Mn, Eu and Mn).
[0086]
For alkaline earth sulfide phosphors, La₂O₂S: Eu, Y₂O₂S: Eu, Gd₂O₂S: Eu etc.
[0087]
For rare earth aluminate phosphors mainly activated with lanthanoid elements such as Ce, Y₃Al₅O₁₂: Ce, (Y_0.8Gd_0.2)₃Al₅O₁₂: Ce, Y₃(Al_0.8Ga_0.2)₅O₁₂: Ce, (Y, Gd)₃(Al, Ga)₅O₁₂There are YAG phosphors represented by the composition formula:
[0088]
Other phosphors include ZnS: Eu, Zn₂GeO₄: Mn, MGa₂S₄: Eu (M is at least one selected from Sr, Ca, Ba, Mg and Zn. X is at least one selected from F, Cl, Br and I). M₂Si₅N₈: Eu, MSi₇N₁₀: Eu, M_1.8Si₅O_0.2N₈: Eu, M_0.9Si₇O_0.1N₁₀: Eu (M is at least one selected from Sr, Ca, Ba, Mg, Zn).
[0089]
The above-mentioned second phosphor may be one or more selected from Tb, Cu, Ag, Au, Cr, Nd, Dy, Co, Ni, and Ti instead of Eu or in addition to Eu as desired. Can also be included.
[0090]
Moreover, it is fluorescent substance other than the said fluorescent substance, Comprising: The fluorescent substance which has the same performance and effect can also be used.
[0091]
As these second phosphors, phosphors having emission spectra in yellow, red, green, and blue can be used by the excitation light of the light-emitting elements 10 and 101, and yellow, blue-green, which are intermediate colors thereof, can be used. A phosphor having an emission spectrum in orange or the like can also be used. By using these second phosphors in combination with the first phosphor, light emitting devices having various emission colors can be manufactured.
[0092]
For example, the first phosphor, CaSi that emits light from green to yellow₂O₂N₂: Eu or SrSi₂O₂N₂: Eu and blue light that is the second phosphor (Sr, Ca)₅(PO₄)₃Cl: Eu, emits red light (Ca, Sr)₂Si₅N₈: By using the phosphors 11 and 108 made of Eu, a light emitting device that emits white light with good color rendering can be provided. This uses the three primary colors of red, blue, and green, so the desired white light can be achieved simply by changing the blend ratio of the first phosphor and the second phosphor. Can do.
[0093]
The particle diameter of the phosphors 11 and 108 is preferably in the range of 1 μm to 20 μm, more preferably 2 μm to 8 μm. Particularly, 5 μm to 8 μm is preferable. A phosphor having a particle size smaller than 2 μm tends to form an aggregate. On the other hand, a phosphor having a particle size range of 5 μm to 8 μm has high light absorptivity and conversion efficiency. In this manner, the mass productivity of the light-emitting device is improved by including a phosphor having a large particle diameter and having optically excellent characteristics.
[0094]
Here, the particle size refers to the average particle size obtained by the air permeation method. Specifically, in an environment where the temperature is 25 ° C. and the humidity is 70%, 1 cm³This is a value obtained by measuring a minute sample and packing it in a special tubular container, then flowing a constant pressure of dry air, reading the specific surface area from the differential pressure, and converting it to an average particle size. The average particle size of the phosphor used in the present invention is preferably in the range of 2 μm to 8 μm. Moreover, it is preferable that the phosphor having this average particle diameter value is contained frequently. In addition, it is preferable that the particle size distribution is distributed in a narrow range, and particularly, particles having a particle size of 2 μm or less are preferable. As described above, by using a phosphor having a small variation in particle size and particle size distribution, color unevenness is further suppressed, and a light emitting device having a good color tone can be obtained.
[0095]
The arrangement place of the phosphor 108 in the light emitting device 2 can be arranged at various places in the positional relationship with the light emitting element 101. For example, the phosphor 108 can be contained in the molding material that covers the light emitting element 101. Further, the light emitting element 101 and the phosphor 108 may be arranged with a gap therebetween, or the phosphor 108 may be directly placed on the light emitting element 101.
[0096]
(Coating member 12, 109)
The phosphors 11 and 108 can be attached using various coating members (binders) such as a resin that is an organic material and glass that is an inorganic material. The coating members 12 and 109 may have a role as a binder for fixing the phosphors 11 and 108 to the light emitting elements 10 and 101, the window portion 107, and the like. When an organic material is used as the coating member (binder), a transparent resin having excellent weather resistance such as an epoxy resin, an acrylic resin, or silicone is preferably used as a specific material. In particular, it is preferable to use silicone because it is excellent in reliability and the dispersibility of the phosphors 11 and 108 can be improved.
[0097]
In addition, it is preferable to use an inorganic material that is close to the thermal expansion coefficient of the window portion 107 as the coating members (binders) 12 and 109 because the phosphor 108 can be satisfactorily adhered to the window portion 107. As a specific method, a precipitation method, a sol-gel method, a spray method, or the like can be used. For example, the phosphors 11 and 108 include silanol (Si (OEt)).₃OH) and ethanol are mixed to form a slurry. After the slurry is discharged from a nozzle, the slurry is heated at 300 ° C. for 3 hours to convert silanol into SiO 2.₂And the phosphor can be fixed to a desired place.
[0098]
In addition, an inorganic binder can be used as the coating members (binders) 12 and 109. The binder is so-called low-melting glass, is a fine particle, has little absorption with respect to radiation in the ultraviolet to visible region, and is extremely stable in the coating members (binders) 12 and 109. Is preferred.
[0099]
In addition, when a phosphor having a large particle size is attached to the coating members (binders) 12 and 109, it can be obtained by a binder, for example, silica, alumina, or a precipitation method. It is preferable to use a fine-grained alkaline earth metal pyrophosphate or orthophosphate. These binders can be used alone or mixed with each other.
[0100]
Here, a method for applying the binder will be described. In order to sufficiently enhance the binding effect, the binder is preferably wet pulverized in a vehicle to form a slurry and used as a binder slurry. The vehicle is a high viscosity solution obtained by dissolving a small amount of a binder in an organic solvent or deionized water. For example, an organic vehicle can be obtained by adding 1 wt% of nitrocellulose as a binder to butyl acetate as an organic solvent.
[0101]
The binder slurry thus obtained contains phosphors 11 and 108 to prepare a coating solution. The added amount of the slurry in the coating solution can be such that the total amount of the binder in the slurry is about 1 to 3% wt with respect to the amount of the phosphor in the coating solution. In order to suppress a decrease in the luminous flux maintenance factor, it is preferable that the amount of the binder added is small.
[0102]
The coating solution is applied to the back surface of the window portion 107. After that, hot air or hot air is blown to dry. Finally, baking is performed at a temperature of 400 ° C. to 700 ° C. to scatter the vehicle. As a result, the phosphor layer is adhered to the desired place with the binder.
[0103]
(Light emitting element 10, 101)
In the present invention, the light-emitting elements 10 and 101 are preferably semiconductor light-emitting elements having a light-emitting layer capable of emitting a light emission wavelength capable of efficiently exciting the phosphor. Examples of the material of such a semiconductor light emitting device include various semiconductors such as BN, SiC, ZnSe, GaN, InGaN, InAlGaN, AlGaN, BAlGaN, and BInAlGaN. Similarly, these elements may contain Si, Zn, or the like as an impurity element to serve as a light emission center. In particular, a nitride semiconductor (for example, a nitride semiconductor containing Al or Ga, In or Ga, for example) is used as a light emitting layer material that can efficiently emit short wavelengths of visible light from the ultraviolet region that can excite phosphors 11 and 108 efficiently. In as a nitride semiconductor containing_XAl_YGa_1-XYN, 0 ≦ X, 0 ≦ Y, and X + Y ≦ 1) are more preferable.
[0104]
As a semiconductor structure, a homostructure having a MIS junction, a PIN junction, a pn junction, or the like, a heterostructure, or a double hetero configuration is preferably exemplified. Various emission wavelengths can be selected depending on the semiconductor layer material and the mixed crystal ratio. Further, the output can be further improved by adopting a single quantum well structure or a multiple quantum well structure in which the semiconductor active layer is formed in a thin film that produces a quantum effect.
[0105]
When a nitride semiconductor is used for the light emitting elements 10 and 101, a material such as sapphire, spinel, SiC, Si, ZnO, GaAs, or GaN is preferably used for the semiconductor substrate. In order to form a nitride semiconductor with good crystallinity with high productivity, it is preferable to use a sapphire substrate. A nitride semiconductor can be formed on the sapphire substrate by HVPE method, MOCVD method or the like. A buffer layer made of GaN, AlN, GaAIN or the like is grown at a low temperature on the sapphire substrate to form a non-single crystal, and a nitride semiconductor having a pn junction is formed thereon.
[0106]
As an example of a light emitting device capable of efficiently emitting light in the ultraviolet region having a pn junction using a nitride semiconductor, a SiO 2 layer is formed on the buffer layer substantially perpendicularly to the orientation flat surface of the sapphire substrate.₂Are formed in stripes. GaN is grown on the stripes using EHV (Epitaxial Lateral Over Grows GaN) using the HVPE method. Subsequently, by MOCVD, a first contact layer formed of n-type gallium nitride, a first cladding layer formed of n-type aluminum nitride / gallium, a well layer of indium nitride / aluminum / gallium, and aluminum nitride / gallium An active layer having a multiple quantum well structure in which a plurality of barrier layers are stacked, a second cladding layer formed of p-type aluminum nitride / gallium, and a second contact layer formed of p-type gallium nitride are sequentially stacked. Examples include a double hetero configuration. The active layer may be formed into a ridge stripe shape and sandwiched between guide layers, and a resonator end face may be provided to provide a semiconductor laser device usable in the present invention.
[0107]
Nitride semiconductors exhibit n-type conductivity without being doped with impurities. When forming a desired n-type nitride semiconductor, for example, to improve luminous efficiency, it is preferable to appropriately introduce Si, Ge, Se, Te, C, etc. as an n-type dopant. On the other hand, when forming a p-type nitride semiconductor, it is preferable to dope p-type dopants such as Zn, Mg, Be, Ca, Sr, and Ba. Since nitride semiconductors are not easily converted to p-type by simply doping with a p-type dopant, it is preferable to reduce resistance by heating in a furnace or plasma irradiation after introducing the p-type dopant. When a sapphire substrate is not used, the contact layer is exposed by etching from the p-type side to the surface of the first contact layer. A light emitting element made of a nitride semiconductor can be formed by cutting the semiconductor wafer into chips after forming electrodes on each contact layer.
[0108]
In order to form the light emitting device of the present invention with high productivity, it is preferable to form the phosphors 11 and 108 using a resin when the phosphors 11 and 108 are fixed to the light emitting elements 10 and 101. In this case, taking into consideration the emission wavelength from the phosphors 11 and 108 and the deterioration of the translucent resin, the light-emitting elements 10 and 101 have an emission spectrum in the ultraviolet region, and the emission peak wavelength is 360 nm or more and 420 nm or less. And those having a wavelength of 450 nm to 470 nm are preferable.
[0109]
Here, the semiconductor light emitting devices 10 and 101 used in the present invention have an impurity concentration of 10¹⁷-10²⁰/ Cm³It is preferable that the sheet resistance of the n-type contact layer and the sheet resistance of the light-transmitting p electrode are adjusted so as to satisfy the relationship of Rp ≧ Rn. The n-type contact layer is preferably formed to a film thickness of, for example, 3 to 10 μm, more preferably 4 to 6 μm, and the sheet resistance is estimated to be 10 to 15Ω / □, so that Rp at this time is the sheet resistance value. It is good to form in a thin film so that it may have the above sheet resistance values. The translucent p-electrode may be formed of a thin film having a thickness of 150 μm or less.
[0110]
Further, when the translucent p-electrode is formed of a multilayer film or alloy composed of one kind selected from the group of gold and platinum group elements and at least one other element, it is contained. When the sheet resistance of the translucent p-electrode is adjusted by the content of the gold or platinum group element, stability and reproducibility are improved. Since gold or a metal element has a high absorption coefficient in the wavelength region of the semiconductor light emitting device used in the present invention, the smaller the amount of gold or platinum group element contained in the translucent p-electrode, the better the transparency. In the conventional semiconductor light emitting device, the relationship of sheet resistance is Rp ≦ Rn. However, in the present invention, Rp ≧ Rn, and therefore the translucent p-electrode is formed in a thin film as compared with the conventional one. However, thinning can be easily performed by reducing the content of gold or platinum group elements.
[0111]
As described above, in the semiconductor light emitting devices 10 and 101 used in the present invention, the sheet resistance RnΩ / □ of the n-type contact layer and the sheet resistance RpΩ / □ of the translucent p electrode have a relationship of Rp ≧ Rn. Preferably. It is difficult to measure Rn after forming the semiconductor light emitting devices 10 and 101, and it is practically impossible to know the relationship between Rp and Rn. However, from the state of the light intensity distribution during light emission, what Rp and You can know if it is related to Rn.
[0112]
When the translucent p-electrode and the n-type contact layer have a relationship of Rp ≧ Rn, providing a p-side pedestal electrode in contact with the translucent p-electrode and having an extended conductive portion further improves external quantum efficiency. Can be achieved. There is no restriction on the shape and direction of the extended conductive portion, and when the extended conductive portion is on the satellite, it is preferable because the area for blocking light is reduced, but it may be mesh-shaped. Further, the shape may be a curved shape, a lattice shape, a branch shape, or a hook shape in addition to the linear shape. At this time, since the light shielding effect increases in proportion to the total area of the p-side pedestal electrode, it is preferable to design the line width and length of the extended conductive portion so that the light shielding effect does not exceed the light emission enhancing effect.
[0113]
(Light emitting element 10, 101)
As the light-emitting elements 10 and 101, a light-emitting element that emits blue light different from the above-described ultraviolet light-emitting element can be used. The light emitting elements 10 and 101 that emit blue light are preferably group III nitride compound light emitting elements. The light-emitting elements 10 and 101 include, for example, an n-type GaN layer in which Si is undoped, an n-type contact layer made of n-type GaN in which Si is doped, an undoped GaN layer, and multiple quanta on a sapphire substrate 1 Light emitting layer with a well structure (GaN well layer / InGaN well layer quantum well structure), p-clad layer made of p-type GaN made of Mg-doped p-type GaN, p-type made of p-type GaN doped with Mg It has a laminated structure in which contact layers are sequentially laminated, and electrodes are formed as follows. However, a light emitting element different from this configuration can also be used.
[0114]
The p ohmic electrode is formed on almost the entire surface of the p-type contact layer, and the p pad electrode is formed on a part of the p ohmic electrode.
[0115]
The n-electrode is formed in the exposed portion by removing the undoped GaN layer from the p-type contact layer by etching to expose a part of the n-type contact layer.
[0116]
In the present embodiment, the light emitting layer having a multiple quantum well structure is used. However, the present invention is not limited to this, and for example, a single quantum well structure using InGaN may be used. GaN doped with Zn may be used.
[0117]
The light emitting layers of the light emitting elements 10 and 101 can change the main light emission peak wavelength in the range of 420 nm to 490 nm by changing the In content. The emission peak wavelength is not limited to the above range, and those having an emission peak wavelength in the range of 360 to 550 nm can be used.
[0118]
(Coating member 12, 109)
The coating member 12 (light transmissive material) is provided in the cup of the lead frame 13 and is used by mixing with the phosphor 11 that converts the light emission of the light emitting element 10. Specific materials for the coating member 12 include transparent resins, silica sol, glass, inorganic binders, and the like that are excellent in temperature characteristics and weather resistance, such as epoxy resins, urea resins, and silicone resins. Further, a diffusing agent, barium titanate, titanium oxide, aluminum oxide or the like may be contained together with the phosphor. Moreover, you may contain a light stabilizer and a coloring agent.
[0119]
(Lead frame 13)
The lead frame 13 includes a mount lead 13a and an inner lead 13b.
[0120]
The mount lead 13a is for placing the light emitting element 10 thereon. The upper portion of the mount lead 13a has a cup shape, and the light emitting element 10 is die-bonded in the cup, and the outer peripheral surface of the light emitting element 10 is covered with the phosphor 11 and the coating member 12 inside the cup. . A plurality of light emitting elements 10 can be arranged in the cup, and the mount lead 13 a can be used as a common electrode of the light emitting elements 10. In this case, sufficient electrical conductivity and connectivity with the conductive wire 14 are required. Die bonding (adhesion) between the light emitting element 10 and the cup of the mount lead 13a can be performed with a thermosetting resin or the like. Examples of the thermosetting resin include an epoxy resin, an acrylic resin, and an imide resin. In addition, Ag-ace, carbon paste, metal bumps, or the like can be used for die-bonding and electrical connection with the mount lead 13a by the face-down light emitting element 10 or the like. An inorganic binder can also be used.
[0121]
The inner lead 13b is intended to be electrically connected to the conductive wire 14 extending from the electrode 3 of the light emitting element 10 disposed on the mount lead 13a. The inner lead 13b is preferably disposed at a position away from the mount lead 13a in order to avoid a short circuit due to electrical contact with the mount lead 13a. In the case where the plurality of light emitting elements 10 are provided on the mount lead 13a, it is necessary that the conductive wires be arranged so as not to contact each other. The inner lead 13b is preferably made of the same material as the mount lead 13a, and iron, copper, iron-containing copper, gold, platinum, silver, or the like can be used.
[0122]
(Conductive wire)
The conductive wire 14 is for electrically connecting the electrode 3 of the light emitting element 10 and the lead frame 13. The conductive wire 14 preferably has good ohmic properties, mechanical connectivity, electrical conductivity, and thermal conductivity with the electrode 3. Specific materials for the conductive wire 14 are preferably metals such as gold, copper, platinum, and aluminum, and alloys thereof.
[0123]
(Mold member)
The mold member 15 is provided to protect the light emitting element 10, the phosphor 11, the coating member 12, the lead frame 13, the conductive wire 14, and the like from the outside. In addition to the purpose of protection from the outside, the mold member 15 also has the purposes of widening the viewing angle, relaxing the directivity from the light emitting element 10, and converging and diffusing the emitted light. In order to achieve these objects, the mold member can have a desired shape. Further, the mold member 15 may have a structure in which a plurality of layers are stacked in addition to the convex lens shape and the concave lens shape. As a specific material of the mold member 15, a material excellent in translucency, weather resistance, and temperature characteristics such as epoxy resin, urea resin, silicone resin, silica sol, and glass can be used. The mold member 15 can contain a diffusing agent, a colorant, an ultraviolet absorber, and a phosphor. As the diffusing agent, barium titanate, titanium oxide, aluminum oxide or the like is preferable. In order to reduce the resilience of the material with the coating member 12, it is preferable to use the same material in consideration of the refractive index.
[0124]
Hereinafter, the phosphor and the light emitting device according to the present invention will be described with reference to examples, but the present invention is not limited to these examples.
[0125]
The temperature characteristics are shown as relative luminance with the emission luminance at 25 ° C. being 100%. The particle size indicates the average particle size described above. S. S. S. No. (Fisher Sub Sieve Sizer's No.) Value by air permeation method.
[0126]
【Example】
Examples of the present invention will be described in detail below.
[0127]
(Phosphor)
<Examples 1 to 5>
Table 1 shows the characteristics of Examples 1 to 5 of the oxynitride phosphor according to the present invention.
[0128]
FIG. 3 is a diagram showing an emission spectrum when the oxynitride phosphors of Examples 1 to 5 are excited at Ex = 400 nm. FIG. 4 is a diagram showing an emission spectrum when the oxynitride phosphors of Examples 1 to 5 are excited at Ex = 460 nm. FIG. 5 is a diagram showing excitation spectra of the oxynitride phosphors of Examples 1 to 5. FIG. 6 is a diagram showing the reflection spectra of the oxynitride phosphors of Examples 1 to 5. FIG. 7 is a SEM (scanning electron microscope) photograph of the oxynitride phosphor of Example 1. Here, JIS Z8110 is taken into consideration for the relationship between color names and chromaticity coordinates.
[0129]
[Table 1]

[0130]
Example 1 is CaSi₂O₂N₂: Eu. Example 2 is Ca_0.90Mg_0.10Si₂O₂N₂: Eu. Example 3 is SrSi₂O₂N₂: Eu. Example 4 is Sr_0.90Mg_0.10Si₂O₂N₂: Eu. Example 5 is BaSi₂O₂N₂: Eu.
[0131]
First, the raw material is Ca₃N₂, Si₃N₄, SiO₂, Eu₂O₃It was used. The raw materials were each pulverized to 0.1 to 3.0 μm. After grinding, Example 1 used the following quantities of raw materials.
Ca₃N₂: 6.01 g
Si₃N₄: 5.99g
SiO₂: 7.36g
Eu₂O₃: 0.66g
After weighing the above quantity, Ca₃N₂, Si₃N₄, SiO₂, Eu₂O₃Were mixed in a glove box in a nitrogen atmosphere until uniform. In Examples 1 to 5, the Eu concentration is 0.43 mol%.
[0132]
In Example 1, the mixing ratio (molar ratio) of the raw materials was Ca₃N₂: Si₃N₄: SiO₂: Eu₂O₃= 1: 0.51: 3.02: 0.046. To achieve this mixing ratio, Ca₃N₂(Molecular weight 148.3) 6.01 g, Si₃N₄(Molecular weight 140.3) 5.99 g, SiO₂(Molecular weight 60.09) 7.36 g, Eu₂O₃(Molecular weight 352.0) was weighed to 0.66 g and mixed.
[0133]
The above compounds were mixed, put in a boron nitride crucible in an ammonia atmosphere, and baked at about 1500 ° C. for about 5 hours.
[0134]
Thereby, the target oxynitride phosphor was obtained. The theoretical composition of the obtained oxynitride phosphor is CaSi₂O₂N₂: Eu.
[0135]
When the weight percentage of O and N in the oxynitride phosphor of Example 1 was measured, the total amount contained O at 19.3% and N at 14.5 weight%. The weight ratio of O and N is O: N = 1: 0.75.
[0136]
The oxynitride phosphor according to the example is fired in an ammonia atmosphere using a crucible made of boron nitride. It is not very preferable to use a metal crucible for the crucible. This is because when a metal crucible is used, it is considered that the crucible is eroded and the light emission characteristics are deteriorated. Therefore, it is preferable to use a ceramic crucible such as alumina.
[0137]
Example 2 is an oxynitride phosphor in which a part of Ca is replaced with Mg. Example 2 shows magnesium nitride Mg₃N₂(High purity chemical 98% MGI02PB) (molecular weight 101.0), and the mixing ratio (molar ratio) of the raw materials was Ca₃N₂: Mg₃N₂: Si₃N₄: SiO₂: Eu₂O₃= 1: 0.12: 0.57: 3.37: 0.052 The finely pulverized powder was weighed in the following quantities.
Ca₃N₂: 5.44g
Mg₃N₂: 0.43g
Si₃N₄: 6.05g
SiO₂: 7.43g
Eu₂O₃: 0.67g
Under the same conditions as in Example 1, the raw materials were mixed and fired.
[0138]
Example 3 is an oxynitride phosphor obtained by substituting Ca of Example 1 with Sr. Example 3 shows strontium nitride Sr₃N₄(Molecular weight 290.9) and the mixing ratio (molar ratio) of the raw materials is Sr₃N₂: Si₃N₄: SiO₂: Eu₂O₃= 1: 0.51: 3.02: 0.046 The finely crushed powder was weighed in the following quantities.
Sr₃N₂: 9.14 g
Si₃N₄: 4.65g
SiO₂: 5.71 g
Eu₂O₃: 0.51g
In Example 3, the raw materials were mixed and fired under the same conditions as in Example 1. When the weight percent of O and N of the obtained oxynitride phosphor of Example 3 was measured, 15.3% by weight of O and 11.2% by weight of N were contained in the total amount. The weight ratio of O and N is O: N = 1: 0.73.
[0139]
Example 4 is an oxynitride phosphor obtained by substituting Ca of Example 2 with Sr. In Example 4, the mixing ratio (molar ratio) of the raw materials was Sr₃N₂: Mg₃N₂: Si₃N₄: SiO₂: Eu₂O₃= 1: 0.12: 0.57: 3.37: 0.052 The finely pulverized powder was weighed in the following quantities.
Sr₃N₂: 8.46g
Mg₃N₂: 0.34g
Si₃N₄: 4.80 g
SiO₂: 5.89g
Eu₂O₃: 0.53g
Under the same conditions as in Example 1, the raw materials were mixed and fired.
[0140]
Example 5 is an oxynitride phosphor obtained by substituting Ca of Example 1 with Ba. Example 5 is for barium nitride Ba.₃N₂(Molecular weight 316.6) and the mixing ratio (molar ratio) of the raw materials is Ba₃N₂: Si₃N₄: SiO₂: Eu₂O₃= 1: 0.76: 0.22: 0.033 The finely crushed powder was weighed in the following quantities.
Ba₃N₂11.2 g
Si₃N₄: 3.77g
SiO₂: 4.63 g
Eu₂O₃: 0.42g
Under the same conditions as in Example 1, the raw materials were mixed and fired.
[0141]
The fired products of Examples 1 to 5 are all crystalline powders or granules. The particle size was approximately 1-5 μm.
[0142]
The excitation spectra of the oxynitride phosphors of Examples 1 to 5 were measured. As a result of the measurement, it is strongly excited on the shorter wavelength side than 490 nm.
[0143]
The oxynitride phosphors of Examples 1 to 5 were excited at Ex = 460 nm. Since Ex = 460 nm is a wavelength region often used in blue light emitting elements, excitation was performed in the wavelength region. As a result, the oxynitride phosphor of Example 1 has a light emission color in a yellow-green region having a color tone x = 0.437 and a color tone y = 0.545. The oxynitride phosphor of Example 4 has a light emission color in a yellow-green region having a color tone x = 0.351 and a color tone y = 0.614. All of the oxynitride phosphors of Examples 1 to 5 showed higher luminous efficiency than the conventional phosphors.
[0144]
The oxynitride phosphors of Examples 1 to 5 were excited at Ex = 400 nm. The oxynitride phosphor of Example 1 has a light emission color in a yellow-green region having a color tone x = 0.434 and a color tone y = 0.543. The oxynitride phosphor of Example 3 has an emission color in a yellow-green region having a color tone x = 0.349 and a color tone y = 0.608. All of the oxynitride phosphors of Examples 1 to 5 showed higher luminous efficiency than the conventional phosphors.
[0145]
Moreover, the temperature characteristics were extremely good. The temperature characteristic is indicated by a relative luminance where the emission luminance at 25 ° C. is 100%. The particle size is F.R. S. S. S. No. (Fisher Sub Sieve Sizer's No.) Value by air permeation method. The temperature characteristics of Examples 1 to 5 are 95 to 100% at 100 ° C. It was 65 to 90% at 200 ° C.
[0146]
When X-ray diffraction images of these oxynitride phosphors were measured, all showed sharp diffraction peaks, and it was revealed that the obtained phosphor was a crystalline compound having regularity.
[0147]
<Examples 6 to 15>
Table 2 shows the characteristics of Examples 6 to 15 of the oxynitride phosphor according to the present invention.
[0148]
FIG. 8 is a diagram showing an emission spectrum when the oxynitride phosphors of Examples 6 to 10 are excited at Ex = 400 nm. FIG. 9 is a diagram showing an emission spectrum when the oxynitride phosphors of Examples 6 to 10 are excited at Ex = 460 nm. FIG. 10 is a graph showing an emission spectrum when the oxynitride phosphors of Examples 11 to 15 are excited at Ex = 400 nm. FIG. 11 is a diagram showing an emission spectrum when the oxynitride phosphors of Examples 11 to 15 are excited at Ex = 460 nm. FIG. 12 is a diagram showing excitation spectra of the oxynitride phosphors of Examples 11 to 15. FIG. 13 is a diagram showing the reflection spectra of the oxynitride phosphors of Examples 11 to 15.
[0149]
[Table 2]

[0150]
Examples 6 to 10 are Sr_XCa_(1-X)Si₂O₂N₂: Represented by Eu (0 ≦ X ≦ 1), and is manufactured by changing the molar ratio of Sr and Ca.
[0151]
In Examples 6 to 10, oxynitride phosphors were manufactured under substantially the same conditions as in Example 1. The raw material is Sr₃N₂, Ca₃N₂, Si₃N₄, SiO₂, Eu₂O₃It was used. After weighing the raw material to a predetermined quantity, Sr₃N₂, Ca₃N₂, Si₃N₄, SiO₂, Eu₂O₃Were mixed in a glove box in a nitrogen atmosphere until uniform. In Examples 6 to 15, the Eu concentration is 0.43 mol%.
[0152]
The above compounds were mixed, put in a boron nitride crucible in an ammonia atmosphere, and baked at about 1450 ° C. for about 5 hours.
[0153]
Thereby, the target oxynitride phosphor was manufactured.
[0154]
In Examples 6 to 10, the light emission luminance and the quantum efficiency are expressed as relative values based on Example 6.
[0155]
From these results, when Examples 6 to 10 were excited with a light source in the vicinity of 400 nm, the emission luminance and quantum efficiency were higher when Sr and Ca were mixed than when only Ca was used. On the other hand, when Examples 6 to 10 were excited with a light source near 460 nm, the luminous efficiency was highest when Sr: Ca = 7: 3. Also, as part of Ca is replaced and Sr is increased, the luminous efficiency can be improved. In addition, the color tone can be changed by changing the molar ratio of Sr and Ca.
[0156]
Examples 11 to 15 are Sr_XCa_(10-X)Si₂O₂N₂: Eu (0 ≦ X ≦ 10), which is produced by changing the molar ratio of Sr and Ca.
[0157]
In Examples 11 to 15, oxynitride phosphors were manufactured under substantially the same conditions as in Example 1. The raw material is Sr₃N₂, Ca₃N₂, Si₃N₄, SiO₂, Eu₂O₃It was used. After weighing the raw material to a predetermined quantity, Sr₃N₂, Ca₃N₂, Si₃N₄, SiO₂, Eu₂O₃Were mixed in a glove box in a nitrogen atmosphere until uniform. In Examples 6 to 15, the Eu concentration is 0.43 mol%.
[0158]
The above compounds were mixed, put into a boron nitride crucible in an ammonia atmosphere, and baked at about 1550 ° C. for about 5 hours.
[0159]
Thereby, the target oxynitride phosphor was manufactured.
[0160]
In Examples 11 to 15, light emission luminance and quantum efficiency are expressed as relative values with reference to Example 15.
[0161]
From these results, when Examples 11 to 15 were excited with a light source near 400 nm, the emission luminance and quantum efficiency were higher when Sr and Ca were mixed than when only Sr was used. Further, when the molar ratio of Sr: Ca is Sr: Ca = 6: 4 to 9: 1, the luminous efficiency can be improved. In particular, when Sr: Ca = 7: 3 to 8: 2, both the luminance and quantum efficiency are high. Furthermore, it is possible to change the color tone by changing the molar ratio of Sr and Ca.
[0162]
<Examples 16 to 20>
Table 3 shows the characteristics of Examples 10 and 16 to 20 of the oxynitride phosphor according to the present invention.
[0163]
FIG. 14 is a diagram showing an emission spectrum when the oxynitride phosphors of Examples 10 and 16 to 20 are excited at Ex = 400 nm. FIG. 15 is a graph showing an emission spectrum when the oxynitride phosphors of Examples 10 and 16 to 20 are excited at Ex = 460 nm. FIG. 16 is a diagram showing excitation spectra of the oxynitride phosphors of Examples 10 and 16 to 20. FIG. 17 is a diagram showing the reflection spectra of the oxynitride phosphors of Examples 10 and 16 to 20.
[0164]
[Table 3]

[0165]
In Examples 10, 16 to 20, Sr_XBa_(1-X)Si₂O₂N₂: Represented by Eu (0 ≦ X ≦ 1), and is manufactured by changing the molar ratio of Sr and Ba.
[0166]
In Examples 10 and 16 to 20, oxynitride phosphors were manufactured under substantially the same conditions as in Example 1. The raw material is Sr₃N₂, Ba₃N₂, Si₃N₄, SiO₂, Eu₂O₃It was used. After weighing the raw material to a predetermined quantity, Sr₃N₂, Ba₃N₂, Si₃N₄, SiO₂, Eu₂O₃Were mixed in a glove box in a nitrogen atmosphere until uniform. In Examples 10 and 16 to 20, the Eu concentration is 0.43 mol%.
[0167]
The above compounds were mixed, put in a boron nitride crucible in an ammonia atmosphere, and baked at about 1450 ° C. for about 5 hours.
[0168]
Thereby, the target oxynitride phosphor was manufactured.
[0169]
In Examples 10, 16 to 20, the light emission luminance and the quantum efficiency are expressed as relative values based on Example 10.
[0170]
From this result, when Examples 10 and 16 to 20 were excited with a light source in the vicinity of 400 nm and 460 nm, Sr: Ba = 6: 4 to 8: 2 than when mixed with Sr: Ba = 2: 8. When mixed, the emission luminance and quantum efficiency were higher. Also, as part of Ba is replaced and Sr is increased, the light emission efficiency can be improved. In addition, the color tone can be changed by changing the molar ratio of Sr and Ca. Furthermore, BaSi2N2O2: Eu of Example 20 has a light emission peak wavelength in the vicinity of 496 nm and exhibits high light emission efficiency. By using the oxynitride phosphor according to Example 20, it is possible to improve the color rendering properties of the white light emitting device.
[0171]
<Examples 21 to 24>
Table 4 shows the characteristics of Examples 21 to 24 of the oxynitride phosphor according to the present invention.
[0172]
FIG. 18 is a diagram showing an emission spectrum when the oxynitride phosphors of Examples 21 to 24 are excited at Ex = 400 nm. FIG. 19 is a diagram showing an emission spectrum when the oxynitride phosphors of Examples 21 to 24 are excited at Ex = 460 nm. FIG. 20 is a diagram showing excitation spectra of the oxynitride phosphors of Examples 21 to 24. FIG. 21 is a diagram showing the reflection spectra of the oxynitride phosphors of Examples 21 to 24.
[0173]
[Table 4]

[0174]
Examples 21-24 are Ca_XBa_(1-X)Si₂O₂N₂: Eu (0 ≦ X ≦ 1), and the production is carried out by changing the molar ratio of Ca and Ba.
[0175]
In Examples 21 to 24, oxynitride phosphors were manufactured under substantially the same conditions as in Example 1. The raw material is Ca₃N₂, Ba₃N₂, Si₃N₄, SiO₂, Eu₂O₃It was used. After weighing the raw material to a predetermined quantity, Ca₃N₂, Ba₃N₂, Si₃N₄, SiO₂, Eu₂O₃Were mixed in a glove box in a nitrogen atmosphere until uniform. In Examples 21 to 24, the Eu concentration is 0.43 mol%.
[0176]
The above compounds were mixed, put in a boron nitride crucible in an ammonia atmosphere, and baked at about 1450 ° C. for about 5 hours.
[0177]
Thereby, the target oxynitride phosphor was manufactured.
[0178]
In Examples 21 to 24, the light emission luminance and the quantum efficiency are expressed as relative values based on Example 21.
[0179]
From this result, when Examples 21 to 24 were excited with a light source in the vicinity of 400 nm, when mixing with Ca: Ba = 8: 2 than when mixing with Ca: Ba = 4: 6, It showed high emission brightness and quantum efficiency. On the other hand, when Examples 21 to 24 were excited with a light source near 460 nm, the light emission was higher when mixed with Ca: Ba = 8: 2 than when mixed with Ca: Ba = 2: 8. It showed brightness and quantum efficiency. In addition, the color tone can be changed by changing the molar ratio of Ca and Ba.
[0180]
<Examples 25 to 27>
Structural analysis was performed on the oxynitride phosphors of Examples 25 to 27. The composition of Example 25 is CaSi.₂O₂N₂It is. The composition of Example 26 is SrSi.₂O₂N₂It is. The composition of Example 27 is BaSi.₂O₂N₂It is. FIG. 22 is a schematic diagram showing an orthorhombic system. FIG. 23 is an X-ray diffraction pattern of the oxynitride phosphor of Example 25. FIG. 24 is a view showing an X-ray diffraction pattern of the oxynitride phosphor of Example 26. 25 is a view showing an X-ray diffraction pattern of the oxynitride phosphor of Example 27. FIG.
[0181]
From this result, the unit cell of the crystal of the silicon nitride phosphor belongs to the orthorhombic system. The orthorhombic system has a ≠ b ≠ c and α = β = γ = 90 °, and has two two-fold symmetry axes perpendicular to each other or two symmetry planes intersecting the two-fold symmetry axis.
[0182]
<Light emitting device>
A light emitting device of Example 1 was manufactured using the oxynitride phosphor described above. A light emitting element having an emission spectrum of 400 nm is used as an excitation light source. The phosphor is the CaSi of Example 1.₂O₂N₂: Eu and Ca₂Si₅N₈: Eu and (Ca_0.93, Eu_0.05, Mn_0.02)₁₀(PO₄)₆Cl₂Is used. FIG. 1 shows a light emitting device according to the present invention. FIG. 26 is a plan view showing a light emitting device according to the present invention. FIG. 27 is a cross-sectional view showing A-A ′ of the light emitting device according to the present invention. 28 is a graph showing an emission spectrum of the light emitting device of Example 1. FIG. FIG. 29 is a diagram showing chromaticity coordinates of the light emitting device of Example 1 according to the present invention.
[0183]
(Light emitting element)
The substrate 201 made of sapphire (C surface) is set in a MOVPE reaction vessel, and the temperature of the substrate 201 is raised to about 1050 ° C. while flowing hydrogen to clean the substrate 201.
[0184]
In this embodiment, a sapphire substrate is used as the substrate 201. However, a different type substrate different from a nitride semiconductor, or a nitride semiconductor substrate such as AlN, AlGaN, or GaN may be used as the substrate 201. Examples of the heterogeneous substrate include sapphire and spinel (MgAl₂O₄It is possible to grow a nitride semiconductor such as an insulating substrate such as SiC (including 6H, 4H, 3C), ZnS, ZnO, GaAs, Si, and an oxide substrate lattice-matched with a nitride semiconductor, A substrate material different from the nitride semiconductor can be used. Preferable heterogeneous substrates include sapphire and spinel. Further, the heterogeneous substrate may be off-angle, and in this case, it is preferable to use a step-off-angle substrate because the growth of the underlayer 202 made of gallium nitride grows with good crystallinity. Further, in the case of using a heterogeneous substrate, after growing a nitride semiconductor to be the base layer 202 before forming the element structure on the heterogeneous substrate, the heterogeneous substrate is removed by a method such as polishing, and the nitride semiconductor alone An element structure may be formed as a substrate, or a method of removing a heterogeneous substrate after the element structure is formed. In addition to the GaN substrate, a nitride semiconductor substrate such as AlN may be used.
[0185]
(Buffer layer)
Subsequently, the temperature of the substrate 201 is lowered to 510 ° C., hydrogen is used as the carrier gas, ammonia and TMG (trimethyl gallium) are used as the source gas, and a buffer layer (not shown) made of GaN is formed on the substrate 201 at about 100 Å. Grow with film thickness.
[0186]
(Underlayer)
After growing the buffer layer, only TMG is stopped and the temperature of the substrate 201 is raised to 1050 ° C. When the temperature reaches 1050 ° C., TMG and ammonia gas are also used as source gases, and an undoped GaN layer is grown to a thickness of 2 μm.
[0187]
(N-type layer)
Subsequently, at 1050 ° C., similarly, TMG, ammonia gas, and silane gas are used as source gas and silane gas as impurity gas.¹⁸/ Cm³An n-type layer 203 made of doped GaN is grown to a thickness of 3 μm as an n-side contact layer forming an n-side electrode 211a as an n-type layer.
[0188]
(Active layer)
A barrier layer made of Si-doped GaN is grown to a thickness of 50 angstroms, followed by a temperature of 800 ° C., and undoped In using TMG, TMI, and ammonia._0.1Ga_0.7A well layer made of N is grown to a thickness of 50 Å. Then, four layers of barrier layers and three layers of wells are alternately stacked in the order of barrier + well + barrier + well ... + barrier to grow an active layer 204 having a multi-quantum well structure with a total film thickness of 350 angstroms. Let
[0189]
(P-side carrier confinement layer)
Next, TMG, TMA, ammonia, Cp₂Mg (cyclopentadienylmagnesium) is used and Mg is 5 × 10¹⁹/ Cm³Doped Al_0.3Ga_0.7A p-side carrier confinement layer 205 made of N is grown to a thickness of 100 angstroms.
[0190]
(First p-type layer)
Subsequently, TMG, ammonia, Cp₂A first p-type layer 206 made of GaN doped with p-type impurities using Mg is grown to a thickness of 0.1 μm.
[0191]
(Second p-type layer)
As a second p-type layer, a p-side contact layer 208 that forms a p-side electrode 210 on the surface is formed. The p-side contact layer 208 is made of 1 × 10 5 Mg on the current diffusion layer 207.²⁰/ Cm³Doped p-type GaN is grown to a thickness of 150 Å. Since the p-side contact layer 208 is a layer for forming the p-side electrode 210, 1 × 10¹⁷/ Cm³It is desirable to have the above high carrier concentration. 1 × 10¹⁷/ Cm³If it is lower than that, it tends to be difficult to obtain a preferable ohmic with the electrode. Furthermore, when the composition of the contact layer is GaN, a preferable ohmic with the electrode material is easily obtained.
[0192]
After the reaction for forming the element structure is completed, the temperature is lowered to room temperature, and the wafer is annealed in a reaction vessel at 700 ° C. in a nitrogen atmosphere to further reduce the resistance of the p-type layer. The wafer on which the element structure is formed is taken out from the apparatus, and an electrode forming process described below is performed.
[0193]
After annealing, the wafer is taken out of the reaction vessel, a predetermined mask is formed on the surface of the uppermost p-side contact layer 208, and etching is performed from the p-side contact layer 208 side with an RIE (reactive ion etching) apparatus, and the n-side An electrode forming surface is formed by exposing the surface of the contact layer.
[0194]
As the p-side electrode 210, Ni and Au are sequentially stacked to form the p-side electrode 210 made of Ni / Au. The p-side electrode 210 is an ohmic electrode in ohmic contact with the second p-type layer and the p-side contact layer 208. At this time, in the formed electrode branch 210a, the stripe-shaped light emitting portion 209 has a width of about 5 μm, the stripe-shaped electrode branch 210a has a width of about 3 μm, and the stripe-shaped light emitting portions 209 and the electrode branches 210a are alternately formed. To do. Further, only a part of the p-side electrode 210 is formed in the region where the p-side pad electrode is formed, and is formed over the p-side pad electrode to be electrically connected. At this time, only a part of the p-side electrode 210 is formed in the region where the p-side pad electrode is formed, and the p-side pad electrode 210b is formed on the surface of the p-side contact layer 208, and a part of the p-side electrode 210 is formed. It is formed over the side electrode 210 and is electrically connected. At this time, the surface of the p-side contact layer 208 provided with the p-side pad electrode 210b is not in ohmic contact with the p-side electrode 210 and the p-side contact layer 208, and a Schottky barrier is formed between the two. From the portion where the p-side pad electrode 210b is formed, current does not flow directly into the device, but current is injected into the device through the electrically connected electrode branch 210a.
[0195]
Subsequently, the n-side electrode 211a is formed on the exposed surface 203a where the n-type layer 203 is exposed. The n-side electrode 211a is formed by stacking Ti and Al.
[0196]
Here, the n-side electrode 211a is an ohmic electrode in ohmic contact with the exposed surface 203a of the n-type layer 203. After the ohmic p-side electrode 210 and the n-side electrode 211a are formed, each electrode is subjected to ohmic contact by annealing through heat treatment. The p-side ohmic electrode obtained at this time becomes an opaque film that hardly transmits the light emitted from the active layer 204.
[0197]
Subsequently, the entire surface excluding a part or all of the p-side electrode 210 and the n-side electrode 211a, that is, the entire surface of the element such as the exposed surface 203a of the n-type layer 203 and the side surface of the exposed surface 203a is SiO.₂An insulating film is formed. After the formation of the insulating film, bonding pad electrodes are respectively formed on the surfaces of the p-side electrode 210 and the n-side electrode 211a exposed from the insulating film, and are electrically connected to the respective ohmic electrodes. The p-side pad electrode 210b and the n-side pad electrode 211b are formed by stacking Ni, Ti, and Au on each ohmic electrode, respectively.
[0198]
Finally, the substrate 201 is divided to obtain a light-emitting element having a side length of 300 μm.
[0199]
The obtained light emitting device has an emission peak wavelength of about 400 nm.
[0200]
Table 5 shows the characteristics of the light-emitting device of Example 1.
[0201]
[Table 5]

[0202]
From this, the light-emitting device of Example 1 shows luminescent color in a white range. The light emitting device of Example 1 shows an emission spectrum having emission peak wavelengths at 360 to 430 nm, 430 to 500 nm, and 500 to 730 nm. More specifically, emission spectra having emission peak wavelengths at 390 to 410 nm, 455 to 475 nm, and 550 to 600 nm are shown. The phosphor excited by the light-emitting element excited by 400 nm is the CaSi of Example 1.₂O₂N₂: Eu is in the green area, Ca₂Si₅N₈: Eu changes from yellow to reddish area (Ca_0.93, Eu_0.05, Mn_0.02)₁₀(PO₄)₆Cl₂Each have an emission peak wavelength in the blue-based region. Due to the color mixture of the light of these phosphors, an emission color is shown in the white region. By changing the blending amount of these phosphors, white light of various colors is emitted. Therefore, when manufacturing a light emitting device having predetermined white light using ultraviolet light as an excitation light source, the emission color can be changed only by changing the type of phosphor, the mixing ratio, and the like.
[0203]
<Light emitting device>
The light-emitting device of Example 2 relates to a white light-emitting device using a light-emitting element having an emission peak wavelength of 460 nm as an excitation light source. FIG. 1 is a diagram showing a light emitting device according to the present invention.
[0204]
In the light emitting device of Example 2, an n-type and p-type GaN semiconductor layer 2 is formed on a sapphire substrate 1, and an electrode 3 is provided on the n-type and p-type semiconductor layer 2. The lead frame 13 is conductively connected by the conductive wire 14. The upper part of the light emitting element 10 is covered with the phosphor 11 and the coating member 12, and the outer periphery of the lead frame 13, the phosphor 11, the coating member 12, and the like is covered with the mold member 15. The semiconductor layer 2 is formed on the sapphire substrate 1 with n⁺The layers are stacked in the order of GaN: Si, n-AlGaN: Si, n-GaN, GaInN QWs, p-GaN: Mg, p-AlGaN: Mg, and p-GaN: Mg. The n⁺A part of the GaN: Si layer is etched to form an n-type electrode. A p-type electrode is formed on the p-GaN: Mg layer. The lead frame 13 uses iron-containing copper. A cup for mounting the light-emitting element 10 is provided on the upper portion of the mount lead 13a, and the light-emitting element 10 is die-bonded to the bottom surface of the substantially central portion of the cup. Gold is used for the conductive wire 14, and Ni plating is applied to the bump 4 for conductively connecting the electrode 3 and the conductive wire 14. The phosphor 11 is mixed with the phosphor of Example 49 and the YAG phosphor. As the coating member 12, a material obtained by mixing an epoxy resin, a diffusing agent, barium titanate, titanium oxide, and the phosphor 11 at a predetermined ratio is used. The mold member 15 uses an epoxy resin. The bullet-type light emitting device 1 is a cylindrical type in which the upper part of the mold member 15 having a radius of 2 to 4 mm and a height of about 7 to 10 mm is a hemisphere.
[0205]
When a current is passed through the light emitting device of Example 2, the blue light emitting element 10 having an emission peak wavelength at approximately 460 nm emits light. The phosphor 11 covering the semiconductor layer 2 performs color tone conversion on the blue light. As a result, the light emitting device of Example 2 that emits white light can be provided.
[0206]
The phosphor 11 of the light emitting device of Example 2 according to the present invention includes the oxynitride phosphor of Example 1 and CaSrSi.₅N₈: A phosphor 11 mixed with a nitride phosphor represented by Eu is used. The phosphor 11 is mixed together with the coating member 12.
[0207]
In the light emitting device of Example 2, a part of the light of the light emitting element 10 is transmitted. Further, a part of the light of the light emitting element 10 excites the phosphor 11, and the phosphor 11 performs wavelength conversion, and the light of the green color of the oxynitride phosphor and the yellow red to red light of the nitride phosphor. To emit. To provide a light emitting device that emits white light by mixing light of blue light from these light emitting elements 10, green light from an oxynitride phosphor, and yellow red to red light of the nitride phosphor. Can do.
[0208]
<Light emitting device>
FIG. 30 is a diagram showing a cap-type light emitting device according to the present invention.
[0209]
In the light-emitting device of Example 3, the same members as those in the light-emitting device of Example 1 are denoted by the same reference numerals, and description thereof is omitted. The light emitting element 10 uses a light emitting element having an emission peak wavelength at 400 nm.
[0210]
The light emitting device of Example 3 is configured by covering the surface of the mold member 15 of the light emitting device of Example 1 with a cap 16 made of a light transmissive resin in which a phosphor (not shown) is dispersed.
[0211]
A cup for mounting the light emitting element 10 is provided on the top of the mount lead 13a, and the light emitting element 10 is die-bonded to the bottom surface of the substantially central portion of the cup. In the light emitting device of Example 1, the phosphor 11 is provided so as to cover the light emitting element 10 on the upper part of the cup. However, the light emitting device of Example 3 may not be provided. This is because the phosphor 11 is not provided on the light emitting element 10 so that it is not directly affected by the heat generated from the light emitting element 10.
[0212]
The cap 16 has the phosphor uniformly dispersed in the light transmissive resin. The light transmissive resin containing the phosphor is molded into a shape that fits into the shape of the mold member 15 of the light emitting device 1. Alternatively, a manufacturing method is also possible in which a light-transmitting resin containing a phosphor is placed in a predetermined mold and then the light-emitting device 1 is pushed into the mold and molded. Specific materials for the light transmissive resin of the cap 16 include transparent resins, silica sol, glass, inorganic binders, and the like that are excellent in temperature characteristics and weather resistance such as epoxy resins, urea resins, and silicone resins. In addition to the above, thermosetting resins such as melamine resins and phenol resins can be used. In addition, thermoplastic resins such as polyethylene, polypropylene, polyvinyl chloride, and polystyrene, thermoplastic rubbers such as styrene-butadiene block copolymer, segmented polyurethane, and the like can also be used. Further, a diffusing agent, barium titanate, titanium oxide, aluminum oxide or the like may be contained together with the phosphor. Moreover, you may contain a light stabilizer and a coloring agent. The phosphor used for the cap 16 is Ca.₂Si₅N₈: Eu nitride phosphor, (Ca_0.95, Eu_0.05)₁₀(PO₄)₆Cl₂The phosphor is used. The phosphor 11 used in the cup of the mount lead 13a is the oxynitride phosphor of Example 3. However, since the phosphor is used for the cap 16, the oxynitride phosphor may be contained in the cap 16, and only the coating member 12 may be contained in the cup of the mount lead 13a.
[0213]
In the light emitting device configured as described above, part of the light emitted from the light emitting element 10 excites the oxynitride phosphor of the phosphor 11 and emits green light. Further, part of the light emitted from the light emitting element 10 or part of the light emitted from the oxynitride phosphor excites the phosphor of the cap 16 and emits light from blue and yellow to red. Thereby, the green light of the oxynitride phosphor and the blue, yellow, and red light of the phosphor of the cap 16 are mixed, and as a result, white light is emitted from the surface of the cap 16 to the outside. .
[0214]
【The invention's effect】
In view of the above, the present invention provides an excitation light source in the short-wavelength side region from near ultraviolet to visible light, and a phosphor exhibiting a luminescent color from green to yellow, which is excited by light from the excitation light source. It is a light emitting device having at least. The light emitting device exhibits a bright emission color. In particular, the oxynitride phosphor exhibits a light emission color in a green to yellow region by light from a light emitting element having ultraviolet light. Further, by changing the composition ratio of the oxynitride phosphor, it is possible to provide a light emitting device having excellent light emission characteristics. Further, the light emitting device has high luminous efficiency and excellent reproducibility. Therefore, the present invention has a very important technical significance that the light emitting device as described above can be provided.
[Brief description of the drawings]
FIG. 1 is a view showing a bullet-type light emitting device 1 according to the present invention.
FIG. 2A is a plan view showing a surface-mounted light-emitting device according to the present invention. (B) It is sectional drawing of the surface mount type light-emitting device based on this invention.
FIG. 3 is a diagram showing an emission spectrum when the oxynitride phosphors of Examples 1 to 5 are excited at Ex = 400 nm.
4 is a diagram showing emission spectra when the oxynitride phosphors of Examples 1 to 5 are excited at Ex = 460 nm. FIG.
FIG. 5 is a diagram showing excitation spectra of the oxynitride phosphors of Examples 1 to 5.
6 is a graph showing the reflection spectra of the oxynitride phosphors of Examples 1 to 5. FIG.
7 is an SEM photograph obtained by photographing the oxynitride phosphor of Example 1. FIG.
FIG. 8 is a graph showing an emission spectrum when the oxynitride phosphors of Examples 6 to 10 are excited at Ex = 400 nm.
FIG. 9 is a graph showing an emission spectrum when the oxynitride phosphors of Examples 6 to 10 are excited at Ex = 460 nm.
10 is a graph showing an emission spectrum when the oxynitride phosphors of Examples 11 to 15 are excited at Ex = 400 nm. FIG.
FIG. 11 is a graph showing an emission spectrum when the oxynitride phosphors of Examples 11 to 15 are excited at Ex = 460 nm.
12 is a diagram showing excitation spectra of oxynitride phosphors of Examples 11 to 15. FIG.
FIG. 13 is a diagram showing the reflection spectra of the oxynitride phosphors of Examples 11 to 15.
14 is a graph showing an emission spectrum when the oxynitride phosphors of Examples 10 and 16 to 20 are excited at Ex = 400 nm. FIG.
15 is a graph showing an emission spectrum when the oxynitride phosphors of Examples 10 and 16 to 20 are excited at Ex = 460 nm. FIG.
FIG. 16 is a diagram showing excitation spectra of oxynitride phosphors of Examples 10 and 16 to 20.
FIG. 17 is a diagram showing the reflection spectra of the oxynitride phosphors of Examples 10 and 16 to 20.
18 is a graph showing an emission spectrum when the oxynitride phosphors of Examples 21 to 24 are excited at Ex = 400 nm. FIG.
FIG. 19 is a diagram showing an emission spectrum when the oxynitride phosphors of Examples 21 to 24 are excited at Ex = 460 nm.
FIG. 20 is a diagram showing excitation spectra of the oxynitride phosphors of Examples 21 to 24.
FIG. 21 is a diagram showing the reflection spectra of the oxynitride phosphors of Examples 21 to 24.
FIG. 22 is a schematic view showing an orthorhombic system.
23 is a view showing an X-ray diffraction pattern of the oxynitride phosphor of Example 25. FIG.
24 is a view showing an X-ray diffraction pattern of the oxynitride phosphor of Example 26. FIG.
25 is a view showing an X-ray diffraction pattern of the oxynitride phosphor of Example 27. FIG.
FIG. 26 is a plan view showing a light emitting device according to the present invention.
FIG. 27 is a cross-sectional view showing A-A ′ of the light emitting device according to the present invention.
FIG. 28 is a diagram showing an emission spectrum of the light-emitting device of Example 1 according to the present invention.
FIG. 29 is a diagram showing chromaticity coordinates of the light-emitting device of Example 1 according to the present invention.
FIG. 30 is a view showing a cap-type light emitting device 3 according to the present invention.
[Explanation of symbols]
1 Substrate
2 Semiconductor layer
3 electrodes
4 Bump
10 Light emitting element
11 Phosphor
12 Coating material
13 Lead frame
13a Mount lead
13b Inner lead
14 Conductive wire
15 Mold member
101 Light emitting device
102 Lead electrode
103 Insulating sealing material
104 conductive wire
105 packages
106 Lid
107 windows
108 Phosphor
109 Coating material
201 substrate
202 Underlayer
203 n-type layer
203a Exposed surface
204 Active layer
205 p-side carrier confinement layer
206 1st p-type layer
207 Current spreading layer
208 p-side contact layer
209 Light emitting part
210 p-side electrode
210a Electrode branch
210b p-side pad electrode
211a n-side electrode
211b n-side pad electrode

Claims (12)

An excitation light source;
A phosphor for wavelength-converting at least part of the light from the excitation light source;
A light emitting device comprising:
The phosphor has an emission peak wavelength in a blue-green to yellow-red system region, and contains an oxynitride phosphor having an orthorhombic crystal ,
The oxynitride phosphor is represented by a general formula Sr _x Ca _1-x Si ₂ O ₂ N ₂ : Eu (0.3 ≦ x ≦ 0.7), and more than CaSi ₂ O ₂ N ₂ : Eu. A light emitting device characterized in that an emission peak wavelength is a short wavelength. An excitation light source;
A phosphor for wavelength-converting at least part of the light from the excitation light source;
A light emitting device comprising:
The phosphor includes an oxynitride phosphor having an emission peak wavelength in a blue-green to yellow-red system region and having an orthorhombic crystal , and the oxynitride phosphor has a general formula Ca _x Ba. _1-x Si ₂ O ₂ N ₂ : Eu (0.2 ≦ x ≦ 0.4). 3. The light emitting device according to claim 1, wherein the oxynitride phosphor has an excitation spectrum having a higher intensity at 370 nm than at 500 nm. 4. The light emitting device according to claim 1, wherein the excitation light source has at least one emission peak wavelength in a short wavelength side region of ultraviolet to visible light. The light emitting device according to claim 1, wherein the excitation light source is a light emitting element. The light emitting device according to claim 5, wherein the light emitting layer of the light emitting element includes a nitride semiconductor containing In. The phosphor contains a second phosphor used together with an oxynitride phosphor,
The second phosphor converts at least a part of light from the excitation light source and light from the oxynitride phosphor, and has an emission peak wavelength in a visible light region. The light emitting device according to claim 1, wherein the light emitting device is a light emitting device. The light emitting device according to claim 7, wherein the second phosphor has at least one emission peak wavelength from a blue region to a green, yellow, and red region. The light emitting device
A portion of the light from the excitation light source;
Light from the oxynitride phosphor;
9. The light emitting device according to claim 7, wherein at least two of the light from the second phosphor are mixed and emitted. The light emitting device has an intermediate emission color from an emission peak wavelength of the excitation light source to an emission peak wavelength of the oxynitride phosphor or an emission peak wavelength of the second phosphor. The light emitting device according to any one of claims 7 to 9. The light emitting device according to claim 10, wherein the intermediate light emission color is white light emission. The light emitting device according to any one of claims 7 to 11, wherein the light emitting device has an emission spectrum having at least one emission peak wavelength at 430 nm to 500 nm and 500 nm to 730 nm.

Images