JP3358072B2 - Gallium nitride based semiconductor light emitting device - Google Patents
Gallium nitride based semiconductor light emitting deviceInfo
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- JP3358072B2 JP3358072B2 JP32822394A JP32822394A JP3358072B2 JP 3358072 B2 JP3358072 B2 JP 3358072B2 JP 32822394 A JP32822394 A JP 32822394A JP 32822394 A JP32822394 A JP 32822394A JP 3358072 B2 JP3358072 B2 JP 3358072B2
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- gan
- gallium nitride
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Description
【０００１】[0001]
【産業上の利用分野】本発明は、窒化ガリウム（Ｇａ
Ｎ）系半導体発光素子に関する。なお、本明細書におい
ては、ＧａＮ系半導体の結晶とは、ＧａＮ、ＡｌＮ（窒
化アルミニウム）、ＩｎＮ（窒化インジウム）及びそれ
らの混晶であるＩｎx Ｇａy Ａｌ1-x-y Ｎ（０≦ｘ，０
≦ｙ，ｘ＋ｙ≦１）を含むものである。BACKGROUND OF THE INVENTION The present invention relates to gallium nitride (Ga) nitride.
N) -based semiconductor light-emitting device. In the present specification, the GaN-based semiconductor crystal, GaN, AlN (aluminum nitride), InN is (indium nitride), and their mixed crystal In x Ga y Al 1-xy N (0 ≦ x, 0
≦ y, x + y ≦ 1).
【０００２】[0002]
【従来の技術】近時、緑色から青色にかけての可視光及
び紫外光を発する発光材料としてＧａＮ系半導体が注目
されており、ＧａＮ系半導体結晶よりなる発光層を備え
た発光素子の開発が行なわれている。従来、そのような
発光素子を製造するにあたり、ＧａＮ系半導体結晶をエ
ピタキシャル成長させる基板として、ＧａＮ系半導体結
晶と同じ六方晶系であるサファイア（α−Ａｌ2 Ｏ3 ）
の基板を用いていた。2. Description of the Related Art Recently, GaN-based semiconductors have been attracting attention as light-emitting materials that emit visible light and ultraviolet light from green to blue, and light-emitting devices having a light-emitting layer made of GaN-based semiconductor crystals have been developed. ing. Conventionally, when manufacturing such a light emitting device, sapphire (α-Al 2 O 3 ), which is the same hexagonal system as the GaN-based semiconductor crystal, is used as a substrate on which the GaN-based semiconductor crystal is epitaxially grown.
Substrate was used.
【０００３】しかし、その際のＧａＮ系半導体結晶とサ
ファイア基板との格子定数のずれは１６％（ＧａＮの場
合）にもなり、格子不整合に起因した結晶欠陥がエピタ
キシャル成長膜中に導入されてしまい、結晶性の優れた
ＧａＮ系半導体層が得られないという問題点があった。
また、絶縁体である基板の裏面に電極を形成することが
できず、図３に示す従来例のように、発光層よりも下層
のエピタキシャル成長層（図３では、ｎ型ＧａＮ層３
Ｂ）に達するように穴をあけ、その穴の底、即ちｎ型Ｇ
ａＮ層３Ｂ上に接して電極（負電極）９を形成しなけれ
ばならなかった。従って、発光素子の製造プロセスが複
雑になる、発光素子全体の占める大きさに対して発光面
積が小さくなる、ｎ型ＧａＮ層３Ｂを厚く形成しなけれ
ばならない、などの不都合があった。However, the deviation of the lattice constant between the GaN-based semiconductor crystal and the sapphire substrate at that time is as large as 16% (in the case of GaN), and crystal defects due to lattice mismatch are introduced into the epitaxially grown film. In addition, there is a problem that a GaN-based semiconductor layer having excellent crystallinity cannot be obtained.
Further, an electrode cannot be formed on the back surface of the substrate which is an insulator, and an epitaxial growth layer below the light-emitting layer (in FIG. 3, n-type GaN layer 3) as in the conventional example shown in FIG.
A hole is made to reach B), and the bottom of the hole, ie, n-type G
An electrode (negative electrode) 9 had to be formed in contact with the aN layer 3B. Therefore, there are inconveniences such as that the manufacturing process of the light emitting element is complicated, the light emitting area is smaller than the size occupied by the entire light emitting element, and the n-type GaN layer 3B must be formed thicker.
【０００４】その解決策として、サファイア基板上にバ
ッファ層となるＡｌＮ膜を成長させ、そのＡｌＮ膜上に
ＧａＮ系半導体結晶を成長させたもの（特公昭５９−４
８７９４号、特開平２−２２９４７６号）や、ＧａＡｌ
Ｎよりなるバッファ層の上にＧａＮ系半導体結晶を成長
させたもの（特開平４−２９７０２３号）などが提案さ
れている。これらの提案によれば、サファイア基板とＧ
ａＮ系半導体結晶との格子不整合が緩和されてＧａＮ系
半導体結晶の表面モフォロジや結晶性が向上し、発光輝
度の向上が期待される。As a solution to this problem, an AlN film serving as a buffer layer is grown on a sapphire substrate, and a GaN-based semiconductor crystal is grown on the AlN film (Japanese Patent Publication No. Sho 59-4).
8794, JP-A-2-229476), GaAl
A structure in which a GaN-based semiconductor crystal is grown on a buffer layer made of N (Japanese Patent Application Laid-Open No. H4-297023) has been proposed. According to these proposals, sapphire substrates and G
It is expected that the lattice mismatch with the aN-based semiconductor crystal is alleviated, the surface morphology and crystallinity of the GaN-based semiconductor crystal are improved, and the emission luminance is improved.
【０００５】また、他の解決策として、ＺｎＯが六方晶
系であり、ＧａＮ系半導体結晶との格子不整合が小さい
ことから、基板に導電性のＺｎＯを用いたもの（特開平
４−２１３８７８号）や、ガラスなどの基板上にバッフ
ァ層としてＺｎＯを形成したもの（特公平１−５２９１
０号）などが提案されている。これらの提案によれば、
サファイア上にＧａＮ系半導体結晶を直接成長させた場
合に比べて格子定数の不一致が大きく緩和され、発光輝
度の向上が期待される。加えて、導電性ＺｎＯ基板を用
いれば、基板の裏面に電極を形成することができるの
で、上述した製造プロセスの複雑化などの不都合も解消
される。Another solution is to use conductive ZnO for the substrate because ZnO is hexagonal and has a small lattice mismatch with the GaN-based semiconductor crystal (Japanese Unexamined Patent Publication No. 4-213878). ) Or a substrate in which ZnO is formed as a buffer layer on a substrate such as glass (Japanese Patent Publication No. 1-5291).
No. 0) has been proposed. According to these proposals,
Compared to the case where a GaN-based semiconductor crystal is directly grown on sapphire, the mismatch in lattice constant is greatly reduced, and improvement in light emission luminance is expected. In addition, if a conductive ZnO substrate is used, an electrode can be formed on the back surface of the substrate, so that the above-described inconvenience such as complication of the manufacturing process can be solved.
【０００６】[0006]
【発明が解決しようとする課題】しかしながら、上記Ａ
ｌＮバッファ層やＧａＡｌＮバッファ層を設ける提案で
は、基板が絶縁体であることに起因する製造プロセスの
複雑化などの上記不都合は解消されない。また、基板や
バッファ層をＺｎＯとする提案では、ＧａＮ系半導体結
晶の成長温度（略１０００℃）付近で、ＺｎＯの構成元
素である酸素の影響によりＧａＮ系半導体結晶が酸化し
てしまう、或はＺｎＯからＧａＮ系半導体結晶中にＺｎ
が拡散してＧａＮ系半導体結晶がｐ型の導電型または絶
縁性となってしまう、などの特性劣化が起こるという問
題点があった。However, the above A
The proposal of providing the 1N buffer layer and the GaAlN buffer layer does not solve the above-mentioned inconveniences such as the complicated manufacturing process caused by the substrate being an insulator. Further, in the proposal in which the substrate and the buffer layer are made of ZnO, the GaN-based semiconductor crystal is oxidized near the growth temperature (about 1000 ° C.) of the GaN-based semiconductor crystal due to the influence of oxygen which is a constituent element of ZnO. ZnO in GaN-based semiconductor crystal from ZnO
GaN-based semiconductor crystal becomes a p-type conductivity type or becomes insulative due to diffusion of the GaN-based semiconductor crystal.
【０００７】本発明は、上記事情に鑑みなされたもの
で、ＧａＮ系半導体結晶との格子整合性がよく、かつ導
電性を有し、さらにはＧａＮ系半導体結晶の成長時に安
定な基板或はバッファ層を用い、それによって製造が容
易で高品質のＧａＮ系半導体発光素子を得ることを目的
とする。The present invention has been made in view of the above circumstances, and has good lattice matching with a GaN-based semiconductor crystal, has conductivity, and has a stable substrate or buffer during the growth of the GaN-based semiconductor crystal. An object of the present invention is to obtain a high-quality GaN-based semiconductor light-emitting device that is easy to manufacture and that uses a layer.
【０００８】[0008]
【課題を解決するための手段】上記目的を達成するため
に、本発明者は、ＧａＮ系半導体結晶をエピタキシャル
成長させる基板として好適な材料を見つけるべく鋭意研
究を重ねた結果、六方晶系の三酸化二インジウム（Ｉｎ
2 Ｏ3 、通常Ｉｎ2 Ｏ3 はＧａＮ系半導体結晶の成長用
基板として不適な立方晶系である。）が基板材料として
極めて優れた特性を有していることを見い出した。この
六方晶系のＩｎ2 Ｏ3 は、高圧で育成することにより得
られることが知られている（Ｐｒｅｗｉｔｔ ｅｔ ａ
ｌ．，Ｉｎｏｒｇａｎｉｃ Ｃｈｅｍｉｓｔｒｙ，ｖｏ
ｌ．８，１９８５（１９６９））。そこで、本発明者
は、Ｉｎ2 Ｏ3 をサファイアのような六方晶系の基板上
にエピタキシャル成長させることにより、六方晶系のも
のが得られるのではないかと考え、実験を行ない、六方
晶系のＩｎ2 Ｏ3 を成長させることに成功した。Means for Solving the Problems In order to achieve the above object, the present inventors have conducted intensive studies to find a material suitable as a substrate on which a GaN-based semiconductor crystal is epitaxially grown. Indium (In)
2 O 3 , usually In 2 O 3, is a cubic system unsuitable as a substrate for growing a GaN-based semiconductor crystal. ) Was found to have extremely excellent properties as a substrate material. It is known that this hexagonal In 2 O 3 is obtained by growing at a high pressure (Prewitt et a.
l. , Inorganic Chemistry, vo
l. 8, 1985 (1969)). Therefore, the present inventor considered that a hexagonal system could be obtained by epitaxially growing In 2 O 3 on a hexagonal system substrate such as sapphire. In 2 O 3 was successfully grown.
【０００９】本発明は上記事実に基づきなされたもの
で、本発明に係るＧａＮ系半導体発光素子は、六方晶系
の三酸化二インジウムよりなる基板上に直接、発光層を
含む１層以上の窒化ガリウム系半導体層を形成したこと
を特徴とする。この発明において、前記基板は、三酸化
二インジウム中にスズが添加されていることにより、導
電性を有しており、さらに、前記基板の裏面に直接、正
または負のいずれか一方の電極を形成し、かつ、前記窒
化ガリウム系半導体層のうちの最も上の半導体層上に直
接、他方の電極を形成してもよい。The present invention has been made on the basis of the above facts, and a GaN-based semiconductor light-emitting device according to the present invention has at least one nitride layer including a light-emitting layer directly on a hexagonal indium trioxide substrate. A gallium-based semiconductor layer is formed. In the present invention, the substrate has conductivity by being added to tin in indium trioxide, and further has a positive or negative electrode directly on the back surface of the substrate. Alternatively, the other electrode may be formed directly on the uppermost semiconductor layer of the gallium nitride based semiconductor layers.
【００１０】また、本発明に係るＧａＮ系半導体発光素
子は、基板上に直接、六方晶系の三酸化二インジウムよ
りなるバッファ層を形成し、該バッファ層上に、発光層
を含む１層以上の窒化ガリウム系半導体層を形成したこ
とを特徴とする。この発明において、前記基板はサファ
イアであってもよいし、前記バッファ層は、三酸化二イ
ンジウム中にスズが添加されていることにより、導電性
を有していてもよく、さらには、前記バッファ層の一部
は露出しており、そのバッファ層の露出部上に直接、正
または負のいずれか一方の電極を形成し、かつ、前記窒
化ガリウム系半導体層のうちの最も上の半導体層上に直
接、他方の電極を形成してもよい。In the GaN-based semiconductor light-emitting device according to the present invention, a buffer layer made of hexagonal indium trioxide is formed directly on a substrate, and one or more layers including a light-emitting layer are formed on the buffer layer. Wherein the gallium nitride based semiconductor layer is formed. In the present invention, the substrate may be sapphire, and the buffer layer may have conductivity by adding tin to indium trioxide, and further, the buffer layer A part of the layer is exposed, and either a positive electrode or a negative electrode is formed directly on the exposed portion of the buffer layer, and on the uppermost semiconductor layer of the gallium nitride based semiconductor layers. Alternatively, the other electrode may be formed directly.
【００１１】[0011]
【作用】上記した手段によれば、本発明に係る発光素子
は、六方晶系のＩｎ2 Ｏ3 よりなる基板またはバッファ
層上に、ＧａＮ系半導体層をエピタキシャル成長させた
ものであるため、六方晶系のＩｎ2 Ｏ3 と六方晶系のＧ
ａＮ系半導体結晶との格子整合性が著しく改善される。
即ち、六方晶系のＩｎ2 Ｏ3 のａ軸の格子定数は５．４
８７オングストロームであり、ＧａＮのａ軸の格子定数
の√３倍（５．５２４オングストローム）との格子不整
合は０．６％である。また、ＧａＮ系半導体結晶がＧａ
ＮとＡｌＮとの混晶系の場合には、その混晶（六方晶
系）と六方晶系のＩｎ2 Ｏ3 とは完全に格子整合する。According to the above-described means, the light emitting device according to the present invention is obtained by epitaxially growing a GaN-based semiconductor layer on a substrate or a buffer layer made of hexagonal In 2 O 3 , so that the hexagonal crystal is used. System In 2 O 3 and hexagonal system G
Lattice matching with the aN-based semiconductor crystal is significantly improved.
That is, the lattice constant of the a-axis of hexagonal In 2 O 3 is 5.4.
It is 87 Å, and the lattice mismatch with √3 times (5.524 Å) the lattice constant of the a-axis of GaN is 0.6%. Further, the GaN-based semiconductor crystal is Ga
In the case of a mixed crystal of N and AlN, the mixed crystal (hexagonal) and hexagonal In 2 O 3 are completely lattice-matched.
【００１２】また、Ｉｎ2 Ｏ3 は、不純物としてスズ
（Ｓｎ）等を添加することにより、透明電極として広く
用いられているように、導電性を有するとともに、近紫
外部から可視部の全域にわたって透明である。従って、
発光層から発せられる光を損失することなく外部に有効
に取り出すことができる。また、Ｉｎ2 Ｏ3 を基板とし
て用いた場合には、基板裏面に直接電極を形成できるの
で、発光素子の製造プロセスが簡略化される。或は、基
板上にＩｎ2 Ｏ3 のバッファ層を形成する場合には、そ
のバッファ層の一部を露出させてそこに直接電極を形成
できるので、発光層よりも下層のＧａＮ系結晶よりなる
エピタキシャル成長層（図３の従来例のｎ型ＧａＮ層３
Ｂ）を厚く形成せずに済む。ここで、Ｓｎの添加量は、
０．０１〜２０原子％が妥当であり、好ましくは１０原
子％程度であるのがよい。Ｓｎの添加量が１０原子％の
時に、導電性及び光透過性が最適となる。In addition, In 2 O 3 has conductivity by adding tin (Sn) or the like as an impurity, as well as being widely used as a transparent electrode, and extends over the entire region from the near ultraviolet to the visible region. It is transparent. Therefore,
Light emitted from the light emitting layer can be effectively extracted to the outside without loss. Further, when In 2 O 3 is used as a substrate, an electrode can be formed directly on the back surface of the substrate, so that the manufacturing process of the light emitting element is simplified. Alternatively, when a buffer layer of In 2 O 3 is formed on a substrate, a part of the buffer layer is exposed and an electrode can be formed directly on the buffer layer. Epitaxial growth layer (the conventional n-type GaN layer 3 of FIG. 3)
B) need not be formed thick. Here, the amount of Sn added is
0.01 to 20 atomic% is appropriate, and preferably about 10 atomic%. When the added amount of Sn is 10 atomic%, the conductivity and the light transmittance are optimized.
【００１３】さらに、Ｉｎ2 Ｏ3 は、その融点が２００
０℃を超えているため、ＧａＮ系半導体結晶の一般的な
成長温度（略１０００℃）において熱的に安定であると
ともに、ＭＯＣＶＤ法（有機金属気相成長法）によりＧ
ａＮ系半導体結晶を成長させる際に用いるＴＭＧ（トリ
メチルガリウム）等の有機金属原料やＮＨ3 （アンモニ
ア）などの原料ガスに対しても化学的に安定である。Further, In 2 O 3 has a melting point of 200
Since the temperature exceeds 0 ° C., it is thermally stable at a general growth temperature of a GaN-based semiconductor crystal (approximately 1000 ° C.).
It is chemically stable to an organic metal material such as TMG (trimethylgallium) and a source gas such as NH 3 (ammonia) used for growing an aN-based semiconductor crystal.
【００１４】加えて、Ｉｎ2 Ｏ3 は、ＧａＮ系半導体結
晶がＩｎを含む場合には同種の酸化物、或はＩｎ以外の
ＧａやＡｌの場合にはそれらＧａやＡｌと同族元素の酸
化物であるため、ＺｎＯなどのように異族元素の酸化物
に比べて、反応性が低い。In addition, In 2 O 3 is an oxide of the same kind when the GaN-based semiconductor crystal contains In, or an oxide of a homologous element with Ga or Al when Ga or Al other than In is used. Therefore, the reactivity is lower than that of an oxide of a heterogeneous element such as ZnO.
【００１５】[0015]
【実施例】以下に、実施例を挙げて本発明の特徴とする
ところを明らかとする。なお、以下の各実施例は本発明
を具体的に例示したに過ぎず、それら各実施例により本
発明が何ら制限を受けないのはいうまでもない。また、
図１〜図３において、同一の構成要素については同一の
符号を付し、その説明を省略した。The features of the present invention will now be described with reference to examples. It should be noted that the following embodiments are merely specific examples of the present invention, and it goes without saying that the present invention is not limited by these embodiments. Also,
1 to 3, the same components are denoted by the same reference numerals, and description thereof is omitted.
【００１６】（実施例１）先ず、Ｉｎ2 Ｏ3 基板を以下
のようにして作製した。すなわち、Ｉｎ2 Ｏ3 基板作製
用の、厚さ２５０μｍのサファイアよりなる基板を有機
溶剤で洗浄した後、ハイドライドＶＰＥ装置内に設置し
た。そして、基板部を７００℃、Ｉｎ原料部を８５０℃
にそれぞれ保持するとともに、Ａｒ（アルゴン）ガスを
キャリアガスとして流した。その際、Ｉｎ2 Ｏ3 エピタ
キシャル膜中に不純物をドーピングするために、Ｉｎ原
料中にＳｎをモル比率で約１０％程度入れておいた。続
いて、Ｉｎ原料の上流側からＡｒで希釈したＨＣｌ（塩
化水素）ガスを流し、Ｉｎ原料とＨＣｌとの反応生成物
であるＩｎＣｌを基板部に輸送するとともに、Ｉｎ原料
部をバイパスして基板の直前にＡｒ水蒸気（水をバブリ
ングしたＡｒガス）を流し、そのＡｒ水蒸気とＩｎＣｌ
とを次式のように反応させてサファイア基板上にＩｎ2
Ｏ3 をエピタキシャル成長させた。 ２ＩｎＣｌ＋３Ｈ2 Ｏ＝Ｉｎ2 Ｏ3 ＋２ＨＣｌ＋２Ｈ2 (Example 1) First, an In 2 O 3 substrate was manufactured as follows. That is, a substrate made of sapphire having a thickness of 250 μm for preparing an In 2 O 3 substrate was washed with an organic solvent and then placed in a hydride VPE device. Then, the substrate part is 700 ° C., and the In raw material part is 850 ° C.
, And an Ar (argon) gas was flowed as a carrier gas. At that time, in order to dope impurities into the In 2 O 3 epitaxial film, about 10% by mole of Sn was added to the In raw material. Subsequently, HCl (hydrogen chloride) gas diluted with Ar is supplied from the upstream side of the In raw material to transport InCl, which is a reaction product of the In raw material and HCl, to the substrate portion, and bypasses the In raw material portion to remove the substrate. Ar water vapor (Ar gas bubbling water) is flowed immediately before the Ar water vapor and InCl
Are reacted as shown in the following equation to form In 2 on the sapphire substrate.
O 3 was grown epitaxially. 2InCl + 3H 2 O = In 2 O 3 + 2HCl + 2H 2
【００１７】上述したＩｎ2 Ｏ3 のエピタキシャル成長
を例えば５時間行ない、ＳｎドープＩｎ2 Ｏ3 の厚膜を
得た。このＩｎ2 Ｏ3 厚膜をサファイア基板から分離し
て、ＧａＮ系半導体結晶の成長用Ｉｎ2 Ｏ3 基板とし
た。このＩｎ2 Ｏ3 基板の厚さは約１５０μｍであっ
た。また、Ｘ線分析を行なった結果、Ｉｎ2 Ｏ3 は、ａ
軸の長さが５．４８７オングストロームであり、結晶構
造が六方晶系のものであった。また、このＩｎ2 Ｏ3 基
板は、その抵抗率が１０-2Ωcmであり、導電性を有して
いた。The above-mentioned epitaxial growth of In 2 O 3 was performed for, for example, 5 hours to obtain a thick film of Sn-doped In 2 O 3 . This In 2 O 3 thick film was separated from the sapphire substrate to obtain an In 2 O 3 substrate for growing a GaN-based semiconductor crystal. The thickness of the In 2 O 3 substrate was about 150 μm. As a result of X-ray analysis, In 2 O 3
The shaft had a length of 5.487 angstroms and a hexagonal crystal structure. This In 2 O 3 substrate had a resistivity of 10 −2 Ωcm and had conductivity.
【００１８】次いで、以下のようにしてＩｎ2 Ｏ3 基板
上にＧａＮを成長させた。すなわち、Ｉｎ2 Ｏ3 基板を
ＭＯＣＶＤ（有機金属気相成長）装置内に設置した。そ
して、基板温度を９５０℃に保持した。その状態で、Ｈ
2 （水素ガス）に加えて原料ガスとしてＮＨ3 ガスとＴ
ＭＧを流し、Ｉｎ2 Ｏ3 基板上にＧａＮ膜を例えば６０
分間エピタキシャル成長させた。この実施例１で得られ
たＧａＮのエピタキシャル成長膜の厚さは約３μｍであ
り、その表面には殆ど異常成長が認められなかった。比
較のため、サファイアを基板としてその上に直接ＧａＮ
を実施例１と同様にＭＯＣＶＤ法により成長させたとこ
ろ、実施例１で得たＧａＮの表面の異常成長の数は比較
対象の約１０分の１であった。従って、導電性のＩｎ2
Ｏ3 基板上に直接、結晶性の良好なＧａＮ半導体結晶層
を形成できることが確認された。Next, GaN was grown on the In 2 O 3 substrate as follows. That is, the In 2 O 3 substrate was placed in an MOCVD (metal organic chemical vapor deposition) apparatus. Then, the substrate temperature was kept at 950 ° C. In that state, H
2 In addition to (hydrogen gas), NH 3 gas and T
MG is flowed, and a GaN film is formed on the In 2 O 3
Minutes for epitaxial growth. The thickness of the epitaxially grown GaN film obtained in Example 1 was about 3 μm, and almost no abnormal growth was observed on the surface. For comparison, sapphire was used as a substrate and GaN was directly
Was grown by MOCVD in the same manner as in Example 1. As a result, the number of abnormal growths on the GaN surface obtained in Example 1 was about one tenth of that of the comparative object. Therefore, the conductive In 2
It was confirmed that a GaN semiconductor crystal layer having good crystallinity could be directly formed on the O 3 substrate.
【００１９】続いて、従来と同様にして、上記ＧａＮ半
導体結晶層上にさらにＧａＮ系半導体結晶層を積層し
て、図１に一例として示す発光素子を得た。即ち、上述
したようにＳｎドープＩｎ2 Ｏ3 基板１０上に上記Ｇａ
Ｎ半導体結晶層（ｎ型ＧａＮ層３Ａ）を積層した後、そ
の上に順次、ｎ型ＡｌＧａＮ層４、ＺｎドープＩｎＧａ
Ｎ層５、ｐ型ＡｌＧａＮ層６及びｐ型ＧａＮ層７をエピ
タキシャル成長させた。そして、最上層のｐ型ＧａＮ層
７上に直接、正（＋）のオーミック電極８を形成すると
ともに、Ｉｎ2 Ｏ3 基板１０の裏面に負（−）のオーミ
ック電極１１を形成した。実施例１によれば、発光素子
を作製する際に、Ｉｎ2 Ｏ3 基板１０の裏面に直接、電
極１１を設けることができるので、その製造プロセスが
大幅に簡略化される。Subsequently, a GaN-based semiconductor crystal layer was further laminated on the GaN semiconductor crystal layer in the same manner as in the prior art to obtain a light-emitting device shown as an example in FIG. That is, as described above, the above Ga is placed on the Sn-doped In 2 O 3 substrate 10.
After laminating an N semiconductor crystal layer (n-type GaN layer 3A), an n-type AlGaN layer 4 and a Zn-doped InGa
The N layer 5, the p-type AlGaN layer 6, and the p-type GaN layer 7 were epitaxially grown. Then, the positive (+) ohmic electrode 8 was formed directly on the uppermost p-type GaN layer 7, and the negative (−) ohmic electrode 11 was formed on the back surface of the In 2 O 3 substrate 10. According to the first embodiment, when manufacturing the light emitting element, the electrode 11 can be provided directly on the back surface of the In 2 O 3 substrate 10, so that the manufacturing process is greatly simplified.
【００２０】（実施例２）先ず、サファイア基板上にＩ
ｎ2 Ｏ3 よりなるバッファ層を以下のようにして形成し
た。すなわち、面方位（０００１）のサファイア基板を
有機溶剤で洗浄した後、Ｒｆスパッタリング装置内に設
置した。そして、チャンバー内を圧力０．３TorrのＡｒ
雰囲気に保ちながら、モル比率５％のＳｎを入れたＩＴ
Ｏ（indium-tin oxide）よりなるターゲットをスパッタ
ーして、基板上に厚さ５０００オングストロームのＳｎ
ドープＩｎ2 Ｏ3 薄膜（バッファ層）を形成した。その
際、基板温度を特に制御しなかったが、スパッタ中に基
板温度は１００℃程度まで上昇していた。得られたＩｎ
2 Ｏ3 薄膜は、Ｘ線分析の結果、アモルファス状のもの
であり、また、その抵抗率は１０-3Ωcmで導電性を有し
ていた。(Embodiment 2) First, I was placed on a sapphire substrate.
A buffer layer made of n 2 O 3 was formed as follows. That is, a sapphire substrate having a plane orientation of (0001) was washed with an organic solvent and then placed in an Rf sputtering apparatus. Then, the inside of the chamber is Ar at a pressure of 0.3 Torr.
While maintaining the atmosphere, IT with 5% molar ratio of Sn
Sputter a target made of O (indium-tin oxide) to form a 5000 angstrom thick Sn on the substrate.
A doped In 2 O 3 thin film (buffer layer) was formed. At that time, the substrate temperature was not particularly controlled, but the substrate temperature increased to about 100 ° C. during the sputtering. In obtained
As a result of X-ray analysis, the 2 O 3 thin film was in an amorphous state, and had a resistivity of 10 −3 Ωcm and had conductivity.
【００２１】次いで、Ｉｎ2 Ｏ3 バッファ層を形成した
基板をＭＯＣＶＤ装置内に設置し、上記実施例１と同一
条件及び同一手順でＩｎ2 Ｏ3 バッファ層上にＧａＮを
エピタキシャル成長させた。この実施例２で得られたＧ
ａＮのエピタキシャル成長膜の厚さは約３μｍであり、
その表面には殆ど異常成長が認められなかった。比較の
ため、サファイア基板上に直接ＧａＮを実施例２と同様
にして成長させたところ、実施例２で得たＧａＮの表面
の異常成長の数は比較対象の約１０分の１であった。従
って、サファイア基板上に導電性のＩｎ2 Ｏ3 薄膜を形
成したものの上に、結晶性の良好なＧａＮ半導体結晶層
を形成できることが確認された。なお、基板を昇温する
際にアモルファス状のＩｎ2 Ｏ3 膜が再結晶化し、図３
に示した従来の発光素子においてサファイア基板１上に
設けていたＧａＮバッファ層２と同様の効果が生じたと
考えられる。従って、その再結晶化によりアモルファス
状のＩｎ2 Ｏ3 は六方晶系の結晶構造になったことがわ
かった。Next, the substrate on which the In 2 O 3 buffer layer was formed was placed in an MOCVD apparatus, and GaN was epitaxially grown on the In 2 O 3 buffer layer under the same conditions and in the same procedure as in the first embodiment. G obtained in Example 2
The thickness of the epitaxially grown film of aN is about 3 μm,
Almost no abnormal growth was observed on the surface. For comparison, when GaN was directly grown on the sapphire substrate in the same manner as in Example 2, the number of abnormal growth on the surface of GaN obtained in Example 2 was about one-tenth of the comparative object. Therefore, it was confirmed that a GaN semiconductor crystal layer having good crystallinity could be formed on a sapphire substrate on which a conductive In 2 O 3 thin film was formed. When the temperature of the substrate was increased, the amorphous In 2 O 3 film was recrystallized, and FIG.
It is considered that the same effect as the GaN buffer layer 2 provided on the sapphire substrate 1 in the conventional light emitting device shown in FIG. Therefore, it was found that amorphous In 2 O 3 had a hexagonal crystal structure due to the recrystallization.
【００２２】続いて、従来と同様にして、上記ＧａＮ半
導体結晶層上にさらにＧａＮ系半導体結晶層を積層し
て、図２に一例として示す発光素子を得た。即ち、上述
したようにサファイア基板１上のＳｎドープＩｎ2 Ｏ3
バッファ層１２上に上記ＧａＮ半導体結晶層（ｎ型Ｇａ
Ｎ層３Ａ）を積層した後、その上に順次、ｎ型ＡｌＧａ
Ｎ層４、ＺｎドープＩｎＧａＮ層５、ｐ型ＡｌＧａＮ層
６及びｐ型ＧａＮ層７をエピタキシャル成長させた。そ
して、最上層のｐ型ＧａＮ層７上に直接、正（＋）のオ
ーミック電極８を形成するとともに、Ｉｎ2 Ｏ3 バッフ
ァ層１２に達するように穴をあけ、露出したＩｎ2 Ｏ3
バッファ層１２の表面上に直接、負（−）のオーミック
電極９を形成した。実施例２によれば、発光素子を作製
する際に、発光層よりも下層のｎ型ＧａＮ層３Ａを従来
のように厚く形成せずに済むので、その製造プロセスが
簡略化される。Subsequently, a GaN-based semiconductor crystal layer was further laminated on the GaN semiconductor crystal layer in the same manner as in the prior art to obtain a light-emitting device shown as an example in FIG. That is, as described above, Sn-doped In 2 O 3 on the sapphire substrate 1 is used.
On the buffer layer 12, the GaN semiconductor crystal layer (n-type Ga
After stacking the N layers 3A), n-type AlGa
The N layer 4, the Zn-doped InGaN layer 5, the p-type AlGaN layer 6, and the p-type GaN layer 7 were epitaxially grown. Then, a positive (+) ohmic electrode 8 is formed directly on the uppermost p-type GaN layer 7, and a hole is formed so as to reach the In 2 O 3 buffer layer 12, and the exposed In 2 O 3
The negative (-) ohmic electrode 9 was formed directly on the surface of the buffer layer 12. According to the second embodiment, when manufacturing a light emitting device, the n-type GaN layer 3A below the light emitting layer does not need to be formed as thick as in the related art, so that the manufacturing process is simplified.
【００２３】なお、上記実施例１においては、Ｉｎ2 Ｏ
3 基板１０上にｎ型ＧａＮ層３Ａをエピタキシャル成長
させ、また上記実施例２においては、Ｉｎ2 Ｏ3 バッフ
ァ層１２上にｎ型ＧａＮ層３Ａをエピタキシャル成長さ
せたが、それらに限らず、基板１０上またはバッファ層
１２上にＡｌＮ、ＩｎＮ及びそれらとＧａＮとの混晶で
あるＩｎx Ｇａy Ａｌ1-x-y Ｎ（０≦ｘ，０≦ｙ，ｘ＋
ｙ≦１）を成長させても、同様の効果が得られる。In the first embodiment, In 2 O
(3) The n-type GaN layer 3A is epitaxially grown on the substrate 10, and in the second embodiment, the n-type GaN layer 3A is epitaxially grown on the In 2 O 3 buffer layer 12. However, the present invention is not limited thereto. or AlN on the buffer layer 12, a mixed crystal of InN and GaN and their in x Ga y Al 1-xy N (0 ≦ x, 0 ≦ y, x +
The same effect can be obtained by growing y ≦ 1).
【００２４】また、発光素子の構成も上記各実施例のも
のに限らない。各層の導電型もｐ型とｎ型とを入れ代え
てもよく、その場合には、電極８と電極９との極性も逆
になる。Further, the structure of the light emitting element is not limited to those of the above embodiments. The conductivity type of each layer may be switched between p-type and n-type. In this case, the polarities of the electrodes 8 and 9 are also reversed.
【００２５】[0025]
【発明の効果】本発明に係るＧａＮ系半導体発光素子に
よれば、六方晶系の三酸化二インジウムよりなる基板上
に直接、発光層を含む１層以上の窒化ガリウム系半導体
層を形成する、或は基板上に直接、六方晶系の三酸化二
インジウムよりなるバッファ層を形成し、該バッファ層
上に、発光層を含む１層以上の窒化ガリウム系半導体層
を形成するようにしたため、格子整合性が著しく改善さ
れ、さらにＩｎ2 Ｏ3 が熱的及び化学的に安定で、透明
かつ導電性を有するため、発光素子の高品質化及び製造
プロセスの簡略化が図れる。According to the GaN-based semiconductor light-emitting device of the present invention, one or more gallium nitride-based semiconductor layers including a light-emitting layer are formed directly on a hexagonal indium trioxide substrate. Alternatively, a buffer layer made of hexagonal indium trioxide is formed directly on a substrate, and one or more gallium nitride-based semiconductor layers including a light-emitting layer are formed on the buffer layer. Since the alignment is remarkably improved, and In 2 O 3 is thermally and chemically stable, transparent and conductive, the quality of the light emitting element can be improved and the manufacturing process can be simplified.
【図１】本発明に係るＧａＮ系半導体発光素子の実施例
１の構造を示す断面図である。FIG. 1 is a cross-sectional view illustrating a structure of a GaN-based semiconductor light emitting device according to a first embodiment of the present invention.
【図２】本発明に係るＧａＮ系半導体発光素子の実施例
２の構造を示す断面図である。FIG. 2 is a cross-sectional view illustrating a structure of a GaN-based semiconductor light emitting device according to a second embodiment of the present invention.
【図３】従来のＧａＮ系半導体発光素子の構造を示す断
面図である。FIG. 3 is a cross-sectional view illustrating a structure of a conventional GaN-based semiconductor light emitting device.
１ サファイア基板 ２ ＧａＮバッファ層 ３Ａ ｎ型ＧａＮ層 ３Ｂ ｎ型ＧａＮ層 ４ ｎ型ＡｌＧａＮ層 ５ ＺｎドープＩｎＧａＮ層 ６ ｐ型ＡｌＧａＮ層 ７ ｐ型ＧａＮ層 ８ 正のオーミック電極 ９ 負のオーミック電極 １０ ＳｎドープＩｎ2 Ｏ3 基板 １１ 負のオーミック電極 １２ ＳｎドープＩｎ2 Ｏ3 バッファ層Reference Signs List 1 sapphire substrate 2 GaN buffer layer 3A n-type GaN layer 3B n-type GaN layer 4 n-type AlGaN layer 5 Zn-doped InGaN layer 6 p-type AlGaN layer 7 p-type GaN layer 8 positive ohmic electrode 9 negative ohmic electrode 10 Sn-doped In 2 O 3 substrate 11 Negative ohmic electrode 12 Sn-doped In 2 O 3 buffer layer
───────────────────────────────────────────────────── フロントページの続き (56)参考文献 特開 平６−187832（ＪＰ，Ａ) 特開 平５−315647（ＪＰ，Ａ) 特開 平４−68579（ＪＰ，Ａ) 特開 平４−276078（ＪＰ，Ａ) 特開 平６−60723（ＪＰ，Ａ) 特開 平１−52910（ＪＰ，Ａ) 特開 平４−213878（ＪＰ，Ａ) 特開 昭59−48794（ＪＰ，Ａ) 特開 平４−297023（ＪＰ，Ａ) (58)調査した分野(Int.Cl.7，ＤＢ名) H01L 33/00 H01S 5/00 - 5/50 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-6-187832 (JP, A) JP-A-5-315647 (JP, A) JP-A-4-68579 (JP, A) JP-A-4- 276078 (JP, A) JP-A-6-60723 (JP, A) JP-A-1-52910 (JP, A) JP-A-4-213878 (JP, A) JP-A-59-48794 (JP, A) JP-A-4-297023 (JP, A) (58) Fields investigated (Int. Cl. 7 , DB name) H01L 33/00 H01S 5/00-5/50
Claims (7)
基板上に直接、発光層を含む１層以上の窒化ガリウム系
半導体層を形成したことを特徴とする窒化ガリウム系半
導体発光素子。1. A gallium nitride-based semiconductor light-emitting device, wherein at least one gallium nitride-based semiconductor layer including a light-emitting layer is formed directly on a substrate made of hexagonal indium trioxide.
ズが添加されていることにより、導電性を有しているこ
とを特徴とする請求項１記載の窒化ガリウム系半導体発
光素子。2. The gallium nitride based semiconductor light emitting device according to claim 1, wherein said substrate has conductivity by adding tin to indium trioxide.
ずれか一方の電極を形成し、かつ、前記窒化ガリウム系
半導体層のうちの最も上の半導体層上に直接、他方の電
極を形成したことを特徴とする請求項２記載の窒化ガリ
ウム系半導体発光素子。3. A positive or negative electrode is formed directly on the back surface of the substrate, and the other electrode is formed directly on the uppermost semiconductor layer of the gallium nitride based semiconductor layers. 3. The gallium nitride based semiconductor light emitting device according to claim 2, wherein:
ジウムよりなるバッファ層を形成し、該バッファ層上
に、発光層を含む１層以上の窒化ガリウム系半導体層を
形成したことを特徴とする窒化ガリウム系半導体発光素
子。4. A method in which a buffer layer made of hexagonal indium trioxide is formed directly on a substrate, and one or more gallium nitride based semiconductor layers including a light emitting layer are formed on the buffer layer. A gallium nitride based semiconductor light emitting device.
とする請求項４記載の窒化ガリウム系半導体発光素子。5. The gallium nitride based semiconductor light emitting device according to claim 4, wherein said substrate is sapphire.
中にスズが添加されていることにより、導電性を有して
いることを特徴とする請求項４または５記載の窒化ガリ
ウム系半導体発光素子。6. The gallium nitride based semiconductor light emitting device according to claim 4, wherein the buffer layer has conductivity by adding tin to indium trioxide. .
そのバッファ層の露出部上に直接、正または負のいずれ
か一方の電極を形成し、かつ、前記窒化ガリウム系半導
体層のうちの最も上の半導体層上に直接、他方の電極を
形成したことを特徴とする請求項６記載の窒化ガリウム
系半導体発光素子。7. A part of the buffer layer is exposed,
Either a positive or negative electrode is formed directly on the exposed portion of the buffer layer, and the other electrode is formed directly on the uppermost semiconductor layer of the gallium nitride based semiconductor layers. The gallium nitride based semiconductor light emitting device according to claim 6, wherein
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP32822394A JP3358072B2 (en) | 1994-12-28 | 1994-12-28 | Gallium nitride based semiconductor light emitting device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP32822394A JP3358072B2 (en) | 1994-12-28 | 1994-12-28 | Gallium nitride based semiconductor light emitting device |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH08186291A JPH08186291A (en) | 1996-07-16 |
| JP3358072B2 true JP3358072B2 (en) | 2002-12-16 |
Family
ID=18207822
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|---|---|---|---|
| JP32822394A Expired - Lifetime JP3358072B2 (en) | 1994-12-28 | 1994-12-28 | Gallium nitride based semiconductor light emitting device |
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| Country | Link |
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| JP (1) | JP3358072B2 (en) |
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| JP2005159035A (en) * | 2003-11-26 | 2005-06-16 | Sumitomo Electric Ind Ltd | Light emitting diode and light emitting device |
| KR101020958B1 (en) * | 2008-11-17 | 2011-03-09 | 엘지이노텍 주식회사 | Method for manufacturing a gallium oxide substrate, light emitting device and method for fabricating the same |
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1994
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