JP2004207768A - Translucent electrode and its producing process - Google Patents

Translucent electrode and its producing process Download PDF

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JP2004207768A
JP2004207768A JP2004121252A JP2004121252A JP2004207768A JP 2004207768 A JP2004207768 A JP 2004207768A JP 2004121252 A JP2004121252 A JP 2004121252A JP 2004121252 A JP2004121252 A JP 2004121252A JP 2004207768 A JP2004207768 A JP 2004207768A
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layer
light
metal
electrode
translucent
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Hisayuki Miki
久幸 三木
Takashi Udagawa
隆 宇田川
Mineo Okuyama
峰夫 奥山
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Resonac Holdings Corp
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Showa Denko KK
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Abstract

<P>PROBLEM TO BE SOLVED: To provide a translucent electrode for a light emitting semiconductor element having a translucent structure for preventing ball-up effectively, and also to provide its producing process. <P>SOLUTION: The translucent electrode for a light emitting semiconductor element comprises: a first translucent layer of at least one kind of metal selected from a group of Au, Pt and Pd or of an alloy of two kinds or more of metal formed in contact with the surface of a p-type GaN based compound semiconductor and providing ohmic contact; and a second layer of a translucent metal oxide containing an oxide of at least one kind of metal selected from a group of Ni, Cr and Co and formed on the first layer wherein the surface of the second layer does not contain the metal of the first layer. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

本発明は、発光半導体素子に用いられる電極に係わり、特にｐ型ＧａＮ系化合物半導体の表面に接して形成された発光半導体素子用の透光性の電極とその透光性電極の作製方法に関する。   The present invention relates to an electrode used for a light-emitting semiconductor device, and more particularly to a light-transmitting electrode for a light-emitting semiconductor device formed in contact with the surface of a p-type GaN-based compound semiconductor and a method for manufacturing the light-transmitting electrode.

近年、短波長光発光素子用の半導体材料としてＧａＮ系化合物半導体材料が注目を集めている。ＧａＮ系化合物半導体は、サファイア単結晶を始めとして、種々の酸化物基板や III−Ｖ族化合物を基板として、その上に有機金属気相化学反応法（ＭＯＣＶＤ法）や分子線エピタキシー法（ＭＢＥ法）等によって形成される。サファイア基板等の電気的に絶縁体である基板を用いた素子では、ＧａＡｓ、ＧａＰ等の半導体基板を使用した
III−Ｖ族化合物半導体材料とは異なり、基板裏面に電極を設けることができない。よって、正、負一対の電極を発光素子の同じ面に形成する必要がある。 In recent years, GaN-based compound semiconductor materials have attracted attention as semiconductor materials for short-wavelength light-emitting devices. GaN-based compound semiconductors include various oxide substrates such as sapphire single crystals, and III-V compounds as substrates, on which metal organic chemical vapor deposition (MOCVD) and molecular beam epitaxy (MBE) are applied. ) And the like. In an element using an electrically insulating substrate such as a sapphire substrate, a semiconductor substrate such as GaAs or GaP was used.
Unlike III-V compound semiconductor materials, electrodes cannot be provided on the back surface of the substrate. Therefore, it is necessary to form a pair of positive and negative electrodes on the same surface of the light emitting element.

また、ＧａＮ系化合物半導体材料の特性として、横方向への電流拡散が小さいことがある。原因は、エピタキシャル結晶中に多く存在する基板から表面へ貫通する転位の存在であることが考えられるが、詳しいことは判っていない。この特性のため、電極を形成して通電発光させた場合でも、発光領域は電極直下に限定され電極の周囲には広がりにくい。したがって、発光領域は電極直下に限られ、従来の不透明な電極では発光は電極そのものに遮られて上方には取り出されず、発光強度が思うように向上しなかった。   Further, as a characteristic of the GaN-based compound semiconductor material, current diffusion in the lateral direction may be small. The cause is considered to be the existence of dislocations that penetrate from the substrate to the surface, which are often present in the epitaxial crystal, but the details are not known. Due to this characteristic, even when an electrode is formed and electricity is emitted, the light emitting region is limited to immediately below the electrode and hardly spreads around the electrode. Therefore, the light-emitting region is limited directly below the electrode, and in the case of a conventional opaque electrode, light emission is blocked by the electrode itself and cannot be taken out upward, and the light emission intensity has not improved as expected.

以上のような問題点を解決するために、ｐ型電極を素子の表面のほぼ全面に形成された非常に薄い金属よりなる透光性の電極とし、電極を通して上面から発光を取り出すという素子構造に関する技術が開示されている（例えば、特許文献１参照。）。この特許公開公報には、電極材料として、例えば、Ａｕ、Ｎｉ、Ｐｔ、Ｉｎ、Ｃｒ、Ｔｉ等を使用し、蒸着した金属膜を５００℃以上の温度で熱処理することにより、金属の昇華を引き起こし、膜厚を０．００１μｍ〜１μｍと薄くすることにより透光性を持たせることができることが記載されている。   In order to solve the above problems, the present invention relates to an element structure in which a p-type electrode is a light-transmitting electrode made of a very thin metal formed on almost the entire surface of the element, and light is extracted from the upper surface through the electrode. A technique is disclosed (for example, refer to Patent Document 1). In this patent publication, for example, Au, Ni, Pt, In, Cr, Ti or the like is used as an electrode material, and the deposited metal film is subjected to a heat treatment at a temperature of 500 ° C. or more to cause sublimation of the metal. It is described that light transmittance can be provided by reducing the film thickness to 0.001 μm to 1 μm.

特開平６−３１４８２２号公報JP-A-6-314822

金属を用いた透光性の薄膜では、金属膜を非常に薄く形成する必要がある。例えば、透光性の電極としてＡｕを用いた場合、光の透過率を３０％としたければ膜厚は約２５ｎｍに制御する必要があり、９０％の透過率を実現しようとすれば、膜厚は約２ｎｍにする必要がある。Ｎｉを用いた場合には、透過率３０％としたければ膜厚は約１３ｎｍ、９０％としたければ、約１．５ｎｍとする必要がある。なお、本明細書において「透光性の電極」とは、電極の下で発生した発光を電極を通して観察可能である電極を指して用いることとする。   In a light-transmitting thin film using a metal, the metal film needs to be formed very thin. For example, when Au is used as the light-transmitting electrode, the film thickness needs to be controlled to about 25 nm if the light transmittance is to be 30%. The thickness needs to be about 2 nm. When Ni is used, the film thickness needs to be about 13 nm when the transmittance is 30%, and about 1.5 nm when it is 90%. Note that in this specification, the term "translucent electrode" refers to an electrode through which light emitted under the electrode can be observed.

また、多くの発光半導体素子の作製においては、金属の電極を形成した後オーミック接触を実現する目的で熱処理を行うことが必要である。しかし、上記のような非常に薄い金属薄膜を用いた電極の場合、オーミック接触を目的とした熱処理の際に、下地との密着性よりも金属の表面張力がまさるために金が球状に凝集してしまう「ボールアップ」と呼ばれる現象を生じる。ボールアップが発生すると、金の薄膜は随所に隙間や亀裂を生じ、電気的な連続性を失い、透光性の電極として機能しなくなる。   Further, in manufacturing many light emitting semiconductor elements, it is necessary to perform a heat treatment for realizing ohmic contact after forming a metal electrode. However, in the case of an electrode using a very thin metal thin film as described above, during heat treatment for ohmic contact, gold aggregates in a spherical shape because the surface tension of the metal is greater than the adhesion to the base. A phenomenon called "ball-up" occurs. When ball-up occurs, the gold thin film generates gaps and cracks everywhere, loses electrical continuity, and does not function as a translucent electrode.

ボールアップを防ぐための手段としては、先ず第一に金属よりなる電極の膜厚を増やすことが挙げられる。しかしながら、膜厚を増加させることは光の透過率の減少を引き起こす結果となり、電極は透光性を失ってしまう。本発明は、透光性でかつボールアップを有効に防止し得る構造の発光半導体素子用の透光性電極とその透光性電極の作製方法を提供することを目的とする。   As a means for preventing the ball-up, first, the film thickness of the electrode made of metal is increased. However, increasing the thickness results in a decrease in light transmittance, and the electrode loses light transmission. An object of the present invention is to provide a light-transmitting electrode for a light-emitting semiconductor element having a light-transmitting structure and a structure capable of effectively preventing ball-up, and a method for manufacturing the light-transmitting electrode.

本出願に係わる発明は、ｐ型ＧａＮ系化合物半導体の表面に接して形成され、透光性でかつオーミック接触が得られる、Ａｕ、Ｐｔ、Ｐｄ、Ｎｉからなる群より選ばれた、少なくとも１種類の金属あるいは２種類以上の金属の合金よりなる第１の層と、該第１の層上に形成された、Ｎｉ、Ｃｒ、Ｃｏ、Ｚｎ、Ｍｇよりなる群より選ばれた少なくとも１種類の金属の酸化物を含む、透光性の金属酸化物よりなる第２の層とを有し、この第２の層の表面には前記第１の層の金属、即ち、Ａｕ、Ｐｔ、Ｐｄ、Ｎｉを含まないようにした発光半導体素子用の透光性電極である。また本出願に係わる発明は、上記発光半導体素子用の透光性電極において、特に、第１層がＡｕよりなり、第２層がＮｉの酸化物よりなるか、あるいはＮｉＯと少量のＮｉよりなることを特徴とする。   The invention according to the present application relates to at least one kind selected from the group consisting of Au, Pt, Pd, and Ni, which is formed in contact with the surface of a p-type GaN-based compound semiconductor and is translucent and capable of obtaining ohmic contact. And a first layer formed of an alloy of two or more metals, and at least one metal selected from the group consisting of Ni, Cr, Co, Zn, and Mg formed on the first layer And a second layer made of a light-transmitting metal oxide containing an oxide of the metal of the first layer, that is, Au, Pt, Pd, Ni This is a light-transmitting electrode for a light-emitting semiconductor element which does not contain any. Further, the invention according to the present application provides the light-transmitting electrode for a light-emitting semiconductor device, in which the first layer is made of Au and the second layer is made of Ni oxide or NiO and a small amount of Ni. It is characterized by the following.

また本出願に係わる発明は、上記発光半導体素子用の透光性電極において、特に、前記第２の層と第１の層との界面近傍の領域において、酸素の組成が第２の層から第１の層に向かって徐々に減少することを特徴とする。また本出願に係わる発明は、上記発光半導体素子用の透光性電極において、特に、前記第２の層に含まれる金属酸化物の主成分である金属元素が第１の層中に含まれていることを特徴とする。   Further, the invention according to the present application is directed to the light-transmitting electrode for a light-emitting semiconductor element, in which, particularly in a region near an interface between the second layer and the first layer, the composition of oxygen is changed from the second layer to the second layer. It is characterized by a gradual decrease toward one layer. The invention according to the present application is directed to the light-transmitting electrode for a light-emitting semiconductor element, in which the first layer contains a metal element which is a main component of the metal oxide contained in the second layer. It is characterized by having.

また本出願に係わる発明は、上記発光半導体素子用の透光性電極において、特に、前記第１の層の膜厚が１ｎｍ以上５００ｎｍ以下であることを特徴とする。また本出願に係わる発明は、上記発光半導体素子用の透光性電極において、特に、前記第２の層の膜厚が１ｎｍ以上１０００ｎｍ以下であることを特徴とする。上記いずれの透光性電極も第２の層の表面には第１の層の金属は含まれていない。   Further, the invention according to the present application is characterized in that in the light-transmitting electrode for a light-emitting semiconductor element, in particular, the first layer has a thickness of 1 nm or more and 500 nm or less. Further, the invention according to the present application is characterized in that, in the light-transmitting electrode for a light-emitting semiconductor element, the second layer has a thickness of 1 nm or more and 1000 nm or less. In any of the above translucent electrodes, the metal of the first layer is not included on the surface of the second layer.

また本出願に係わる発光半導体素子用の透光性電極の作製方法は、ｐ型ＧａＮ系化合物半導体の表面に接して透光性でオーミック接触が得られる金属薄膜からなる第１の層を形成する第１の工程と、第１の層上に金属からなる第２の層を形成する第２の工程と、これを熱処理することによって第２の層を酸化する第３の工程を有し、熱処理後の第２の層の表面には第１の層の金属を含まないようにした発光半導体素子用の透光性電極の作製方法である。   In the method for manufacturing a light-transmitting electrode for a light-emitting semiconductor element according to the present application, a first layer made of a metal thin film that is light-transmitting and can achieve ohmic contact with a surface of a p-type GaN-based compound semiconductor is formed. A first step, a second step of forming a second layer made of metal on the first layer, and a third step of oxidizing the second layer by heat-treating the second step; This is a method for manufacturing a light-transmitting electrode for a light-emitting semiconductor element in which the surface of the second layer does not contain the metal of the first layer.

また本出願に係わる発明は、上記発光半導体素子用の透光性電極の作製方法において、特に、前記第１の工程と第２の工程とを同一装置内で連続して行うことを特徴とする。また本出願に係わる発明は、上記発光半導体素子用の透光性電極の作製方法において、特に、前記第３の工程を酸素を含む雰囲気内で行うことを特徴とする。また本出願に係わる発明は、上記発光半導体素子用の透光性電極の作製方法において、特に、前記第３の工程において、熱処理は温度３００℃以上の温度で１分以上行うことを特徴とする。
上記の透光性電極を発光ダイオードに用いることが出来る。 Further, the invention according to the present application is characterized in that, in the method for manufacturing a light-transmitting electrode for a light-emitting semiconductor element, in particular, the first step and the second step are continuously performed in the same apparatus. . Further, the invention according to the present application is characterized in that, in the method for manufacturing a light-transmitting electrode for a light-emitting semiconductor element, the third step is performed in an atmosphere containing oxygen. Further, the invention according to the present application is characterized in that in the method for manufacturing a light-transmitting electrode for a light-emitting semiconductor element, in particular, in the third step, the heat treatment is performed at a temperature of 300 ° C. or more for 1 minute or more. .
The above light-transmitting electrode can be used for a light-emitting diode.

本発明によれば、透光性でかつボールアップを有効に防止した発光半導体素子用の透光性電極とその透光性電極の形成方法を提供することができる。   According to the present invention, it is possible to provide a light-transmitting electrode for a light-emitting semiconductor element which is light-transmitting and effectively prevents ball-up, and a method of forming the light-transmitting electrode.

なお、本発明は後述する実施例のものに限られるものではなく、例えば、ｐ型半導体に対する第１の層としてはＰｔ、Ｐｄ、Ｎｉを用いることもできる。また、第２の層としてはＣｒ、Ｃｏ、Ｚｎ、Ｍｇを含む酸化物を用いることができる。   The present invention is not limited to the embodiments described below. For example, Pt, Pd, and Ni can be used as the first layer for a p-type semiconductor. Further, an oxide containing Cr, Co, Zn, and Mg can be used for the second layer.

本発明に係わる発光半導体素子用の透光性電極は、ｐ型ＧａＮ系化合物半導体の表面上に形成された透光性の金属からなる第１の層と、該第１の層上に形成された、透光性の金属酸化物を含む第２の層とを有することを特徴とする。そして第２の層の表面には図１に示すように第１の層の金属（図１はＡｕを例示）は含まれていない。ＧａＮ系化合物半導体がｐ型の場合、半導体に接触させる第１の層を形成する金属として、熱処理して良好なオーミック接触を得ることができるＡｕ、Ｐｔ、Ｐｄ、Ｎｉなどから選ぶことができる。また、これらの金属の内の少なくとも２種類を組み合わせた合金を用いてもよい。また、良好なオーミック接触を得るため、これらの金属に対してＺｎ、Ｇｅ、Ｓｎ、Ｂｅ、Ｍｇ等の金属を少なくとも１種類以上不純物として微量添加した合金を使用しても良い。   A light-transmitting electrode for a light-emitting semiconductor device according to the present invention is formed on a first layer made of a light-transmitting metal formed on a surface of a p-type GaN-based compound semiconductor, and formed on the first layer. A second layer containing a light-transmitting metal oxide. As shown in FIG. 1, the surface of the second layer does not contain the metal of the first layer (FIG. 1 exemplifies Au). When the GaN-based compound semiconductor is a p-type, the metal forming the first layer that is brought into contact with the semiconductor can be selected from Au, Pt, Pd, Ni, and the like, which can obtain a good ohmic contact by heat treatment. Further, an alloy in which at least two of these metals are combined may be used. Further, in order to obtain good ohmic contact, an alloy in which a trace amount of at least one kind of metal such as Zn, Ge, Sn, Be, and Mg is added to these metals as impurities may be used.

第２の層に含まれる金属酸化物としては、比較的透光性に優れかつ金属との密着性に優れる酸化物である、Ｎｉ、Ｃｒ、Ｃｏ、Ｚｎ、Ｍｇよりなる群より選ばれた少なくとも１種類の金属の金属酸化物を用いることができる。特に、その中でも透光性であることが広く知られているＮｉＯ、Ｃｒ2 Ｏ3 、ＣｏＯ、またはこれらの金属酸化物に他の金属元素が共存した酸化物を主成分とすることは有用である。また、酸化物は下地の金属に合わせて、密着性の良いものを選ぶことが好ましい。本明細書において「金属酸化物」という言葉は、金属の酸化数の異なる酸化物の混合物を指して用いることとし、また、その中には酸化されていない金属が含まれていても構わないこととする。しかし、第２層は透光性を発揮することが特徴であるので、組成の異なる酸化物のうち、最も透光性となりやすい材料が主成分となっていることが有利であることは言うまでもない。Ｎｉを例にとって説明すると、Ｎｉの酸化物としてはＮｉＯ、Ｎｉ2 Ｏ3 、ＮｉＯ2
、Ｎｉ3 Ｏ4 などが存在することが知られているが、第２層を構成する材料の組成は、これらの内のどれであっても良いし、これらの混合物であっても良い。また、酸化されていない金属であるＮｉそのものが含まれていても構わない。しかしながら、ここに例示した数種類の酸化物のうち、最も有効に透光性を発揮することが知られているのはＮｉＯであり、第２層としてはＮｉＯが主成分であることが有利なことは言うまでもない。 As the metal oxide included in the second layer, at least one selected from the group consisting of Ni, Cr, Co, Zn, and Mg, which is an oxide having relatively excellent translucency and excellent adhesion to a metal. A metal oxide of one type of metal can be used. In particular, it is useful to use NiO, Cr 2 O 3 , CoO, which are widely known to be translucent, or an oxide in which another metal element coexists with these metal oxides as a main component. is there. Further, it is preferable to select an oxide having good adhesion in accordance with the metal of the base. In this specification, the term "metal oxide" is used to refer to a mixture of oxides having different oxidation numbers of the metal, and that a metal that is not oxidized may be included in the mixture. And However, since the second layer is characterized by exhibiting a light-transmitting property, it goes without saying that it is advantageous to use, as a main component, a material most likely to be light-transmitting among oxides having different compositions. . Taking Ni as an example, Ni oxides such as NiO, Ni 2 O 3 , NiO 2
, Ni 3 O 4 and the like are known to exist, but the composition of the material constituting the second layer may be any of these or a mixture thereof. Further, Ni itself, which is a metal that has not been oxidized, may be included. However, among the several types of oxides exemplified here, it is NiO that is known to exhibit the most effective light-transmitting property, and it is advantageous that the second layer is mainly composed of NiO. Needless to say.

金属からなる第１の層と透光性の金属酸化物よりなる第２の層とは、密着性に優れることが好ましい。そのため、上記発明において、発光半導体素子用透光性電極は、前記第２の層と第１の層との界面近傍の領域において、酸素の組成が第２の層から第１の層に向かって徐々に減少し、金属酸化物を含む組成から金属からなる組成に、組成が連続的に変化することが望ましい。また、第１の層内に第２の層に含まれる金属酸化物の金属成分が含まれていることも、第１の層と第２の層の高い密着性を実現するためには好適である。第１の層中の第２の層の成分の濃度は第１の層全体を通して一定でも構わないし、第２の層との界面から半導体表面に向かって濃度が小さくなっていくように勾配がつけられていても構わない。また、第２の層の成分は第１の層全体に含まれていても良いし、第２層との界面側の一部分だけに含まれていても良い。   It is preferable that the first layer made of a metal and the second layer made of a light-transmitting metal oxide have excellent adhesion. Therefore, in the above invention, in the light-transmitting electrode for a light-emitting semiconductor element, in the region near the interface between the second layer and the first layer, the composition of oxygen increases from the second layer toward the first layer. It is desirable that the composition gradually decreases and the composition continuously changes from a composition containing a metal oxide to a composition composed of a metal. It is also preferable that the first layer contains a metal component of the metal oxide contained in the second layer in order to realize high adhesion between the first layer and the second layer. is there. The concentration of the component of the second layer in the first layer may be constant throughout the first layer, or a gradient may be set so that the concentration decreases from the interface with the second layer toward the semiconductor surface. It does not matter. Further, the component of the second layer may be contained in the entire first layer, or may be contained only in a part of the interface side with the second layer.

第１の層の膜厚は、透光性を得るために１ｎｍから５００ｎｍの範囲の膜厚に制御して形成することが好ましい。その中でも、金属に固有の物性値である吸光係数から計算して、光の透過率が１０％から９０％を実現するような膜厚を採用することが好ましい。また、第２の層の膜厚は透光性を実現し、ボールアップ防止効果に優れ且つ透光性の良好な、１ｎｍから１０００ｎｍの範囲にすることが好ましい。   The thickness of the first layer is preferably controlled to be in the range of 1 nm to 500 nm in order to obtain light-transmitting properties. Among them, it is preferable to adopt a film thickness that achieves a light transmittance of 10% to 90%, calculated from the extinction coefficient which is a physical property value specific to the metal. Further, the thickness of the second layer is preferably in the range of 1 nm to 1000 nm, which realizes translucency, has an excellent ball-up prevention effect, and has good translucency.

上記の電極は、オーミック接触が得られる金属からなる第１の層および金属からなる第２の層を形成させておき、酸素を含む雰囲気中で熱処理することにより、表面側の金属からなる第２の層を酸化する方法によって形成することができる。酸素を含む雰囲気とは、酸素ガス（Ｏ2 ）や水蒸気（Ｈ2 Ｏ）等を含む雰囲気である。 The above-mentioned electrode is formed by forming a first layer made of a metal and a second layer made of a metal that can achieve ohmic contact, and performing a heat treatment in an atmosphere containing oxygen to form a second layer made of a metal on the surface side. Can be formed by a method of oxidizing the layer. The atmosphere containing oxygen is an atmosphere containing oxygen gas (O 2 ), water vapor (H 2 O), or the like.

すなわち、上記の発光半導体素子用電極は、オーミック接触が得られるＡｕ、Ｐｔ、Ｐｄ、Ｎｉ等の金属からなる第１の層の上に、Ｎｉ、Ｃｒ、Ｃｏ、Ｚｎ、Ｍｇ等の金属からなる第２の層を形成して、これを酸素を含む雰囲気中で温度３００℃以上で１分以上熱処理することにより作製することが出来る。熱処理の温度及び時間は、酸化させようとする金属に応じて選択する必要がある。我々の検討によれば、本発明において使用できる金属では、全般的に３００℃以下の温度では如何に長時間の処理を行ったとしても完全に均一に酸化することはなかった。処理温度は高い方が安定して金属を酸化できるため、３００℃以上のどのような温度を用いても良いが、半導体が分解しないような温度とすることは当然である。また、我々の検討によれば、熱処理を行う時間として１分以下では、上記の範囲で選択される如何なる高温で処理したとしても完全に均一に酸化することはなかった。よって、熱処理は１分以上行うことが望ましい。雰囲気ガス中の酸素の濃度は、０でなければどのような値をとっても良いが、１ｐｐｍ以上であることが好ましい。   That is, the light emitting semiconductor element electrode is made of a metal such as Ni, Cr, Co, Zn, or Mg on the first layer made of a metal such as Au, Pt, Pd, or Ni from which ohmic contact can be obtained. The second layer is formed and heat-treated at a temperature of 300 ° C. or higher for 1 minute or more in an atmosphere containing oxygen. The temperature and time of the heat treatment need to be selected according to the metal to be oxidized. According to our study, the metals that can be used in the present invention generally did not completely oxidize at a temperature of 300 ° C. or less, no matter how long the treatment was performed. The higher the treatment temperature, the more stable the metal can be oxidized. Therefore, any temperature of 300 ° C. or more may be used, but it is natural that the temperature is set so that the semiconductor is not decomposed. Also, according to our study, when the heat treatment time is 1 minute or less, even at any temperature selected in the above range, the oxidation was not completely uniform. Therefore, it is desirable that the heat treatment be performed for 1 minute or more. The concentration of oxygen in the atmospheric gas may take any value other than 0, but is preferably 1 ppm or more.

また、前述の第１の層に第２の層の成分が含まれている電極構造を形成するためにも、熱処理によって第２の層の成分を第１の層へ拡散させることが有効である。この時、第２の層を酸化させるための熱処理を、第２の層の成分を第２の層より第１の層に拡散させる熱処理と兼ねることができる。また、第２の層を酸化させるための熱処理を、半導体と金属からなる第１の層とのオーミック接触を得るための熱処理と兼ねて実施することが出来る。或いは、第２の層を酸化させるための熱処理と半導体と金属からなる第１の層とのオーミック接触を得るための熱処理とを別々の工程で行ってもよい。   Further, in order to form an electrode structure in which the first layer contains the components of the second layer, it is effective to diffuse the components of the second layer into the first layer by heat treatment. . At this time, heat treatment for oxidizing the second layer can also serve as heat treatment for diffusing components of the second layer from the second layer to the first layer. Further, heat treatment for oxidizing the second layer can be performed also as heat treatment for obtaining ohmic contact between the semiconductor and the first layer formed of metal. Alternatively, heat treatment for oxidizing the second layer and heat treatment for obtaining ohmic contact between the semiconductor and the first layer made of metal may be performed in separate steps.

また金属膜を形成する方法としては、通常の抵抗加熱蒸着法の他、電子線加熱蒸着法、スパッタリング法などを用いることができる。また、第１の層と第２の層は同一装置で連続して形成しても良いし、第１の層を形成した時点でいったん装置から取り出し、別の方法によって第２の層を形成しても良いが、密着性の向上という観点から第１の層と第２の層とは同一装置内で連続して形成することが好ましい。第１の層の上に第２の層となる金属の層を順次積層した電極は、例えば蒸着したままでは金属光沢を呈する濃い色の膜であるが、熱処理による酸化により第２の層となる金属の層が金属酸化物となり透光性を示す。   As a method for forming a metal film, an electron beam heating evaporation method, a sputtering method, or the like can be used in addition to a normal resistance heating evaporation method. Further, the first layer and the second layer may be formed continuously by the same device, or once the first layer is formed, the first layer is taken out of the device, and the second layer is formed by another method. However, the first layer and the second layer are preferably formed continuously in the same device from the viewpoint of improving the adhesion. An electrode in which a metal layer serving as a second layer is sequentially stacked on the first layer is, for example, a dark-colored film that exhibits a metallic luster as deposited, but becomes a second layer by oxidation due to heat treatment. The metal layer becomes a metal oxide and exhibits a light-transmitting property.

金属層と金属酸化物層の平面形状は同じでも良いし、異なっても構わないが、金属層の部分は金属酸化物で覆われていることがより好ましいことは言うまでもない。また、金属酸化物よりなる第２の層は金属よりなる第１の層を完全に覆って、それよりも大きい領域を覆うことができるが、反対側の電極と接触していることは好ましくない。第２層を形成する金属酸化物は、導電性の材料を用いることも可能であり、導電性の材料を第２層として用いた場合に第２の層が両側の電極に接触していると、両側の電極が第２の層を通じて導通してリーク電流を生ずる可能性がある。   The plane shapes of the metal layer and the metal oxide layer may be the same or different, but it is needless to say that the metal layer is more preferably covered with the metal oxide. Further, the second layer made of metal oxide can completely cover the first layer made of metal and cover a larger area, but it is not preferable that the second layer is in contact with the electrode on the opposite side. . As the metal oxide forming the second layer, a conductive material can be used. When a conductive material is used as the second layer, the second layer is in contact with the electrodes on both sides. In addition, the electrodes on both sides may conduct through the second layer to cause a leakage current.

本発明に係わる発光半導体素子用透光性電極およびその作製方法は、発光半導体素子において電極から横方向への電流拡散が小さい、ｐ型ＧａＮ系化合物半導体の場合に有効に用いることが出来る。ＧａＮ系化合物半導体は一般にＡｌＧａＩｎＮで表すことが出来る。   INDUSTRIAL APPLICABILITY The light-transmitting electrode for a light-emitting semiconductor device and the method for manufacturing the same according to the present invention can be effectively used in the case of a p-type GaN-based compound semiconductor having a small current diffusion from the electrode in the lateral direction. A GaN-based compound semiconductor can generally be represented by AlGaInN.

（作用）
本発明の提供する発光半導体素子用電極は、透光性を有し半導体層にオーミック接触する金属薄膜からなる第１の層と、第１の層の表面に形成された、透光性を有し、かつ第１の層と半導体層のオーミック接触を実現するための熱処理に際して、第１の層のボールアップを抑制する、透光性のある金属酸化物を主成分とする第２の層とから構成される。透光性の金属酸化物からなる第２の層は、第１の層の保護層として機能する。金属よりなる第１の層の保護層として透光性の金属酸化物からなる第２の層を用いたことにより、第１の層のボールアップを防止し、半導体とオーミック接触する透光性の電極を安定して製造することが可能となった。またこの時、第２の層の主成分として第１の層と密着性の良い材料を選定したり、第２の層と第１の層との間に酸素の組成勾配を設けたり、第１の層中に第２の層に含まれる金属を拡散させたりすることにより、第１の層と第２の層の間の密着性を向上することができる。この密着性を向上した構成により、金属からなる第１の層と金属酸化物からなる第２の層との剥離を有効に防止することが出来るため、発光半導体素子が安定的に生産できる。 (Action)
An electrode for a light-emitting semiconductor element provided by the present invention has a first layer formed of a metal thin film having a light-transmitting property and in ohmic contact with a semiconductor layer, and a light-transmitting property formed on a surface of the first layer. And a second layer mainly composed of a light-transmitting metal oxide, which suppresses ball-up of the first layer during heat treatment for achieving ohmic contact between the first layer and the semiconductor layer. Consists of The second layer made of a light-transmitting metal oxide functions as a protective layer of the first layer. By using the second layer made of a light-transmitting metal oxide as a protective layer of the first layer made of a metal, ball-up of the first layer can be prevented, and a light-transmitting layer that makes ohmic contact with a semiconductor can be formed. Electrodes can be manufactured stably. At this time, a material having good adhesion to the first layer is selected as a main component of the second layer, a composition gradient of oxygen is provided between the second layer and the first layer, By diffusing the metal contained in the second layer into the first layer, the adhesion between the first layer and the second layer can be improved. With this structure with improved adhesion, the first layer made of a metal and the second layer made of a metal oxide can be effectively prevented from being separated, so that a light-emitting semiconductor element can be stably produced.

また、本発明の提供する発光半導体素子用透光性電極の作製方法は、半導体とオーミック接触する金属の薄膜よりなる第１の層と、熱処理によって第２の層となる金属の層を形成しておき、これを酸素を含む雰囲気中で熱処理することにより第２の層となる金属の層を金属酸化物の第２の層とし、透光性を増大させる。これにより、簡便に透光性の電極を製造することができる。また、第２の層となる金属の層を酸化するための熱処理は、第１の層のオーミック接触を実現させるための熱処理と兼ねることができる。   Further, a method for manufacturing a light-transmitting electrode for a light-emitting semiconductor element provided by the present invention includes forming a first layer made of a thin film of a metal in ohmic contact with a semiconductor, and forming a metal layer to be a second layer by heat treatment. In advance, this is heat-treated in an atmosphere containing oxygen, so that the metal layer serving as the second layer is made to be the second layer of the metal oxide, so that the light transmittance is increased. Thereby, a translucent electrode can be easily manufactured. The heat treatment for oxidizing the metal layer serving as the second layer can also serve as heat treatment for achieving ohmic contact with the first layer.

（実施例１）
本発明に係わる発光半導体素子用透光性電極の一例は、図３の断面図で示すような、サファイア基板上に、ＡｌＮをバッファ層として、ｎ型ＧａＮ層、ＩｎＧａＮ層、ｐ型ＡｌＧａＮ層、ｐ型ＧａＮ層を順に積層した半導体基板９のｐ型ＧａＮ層上に、Ａｕからなる第１の層１０、Ｎｉの酸化物からなる第２の層１１を形成して作製した電極である。なお図３で７はｐ側電極ボンディング用パッド、８はｎ側電極である。また図２は、図３で示した発光半導体素子用電極の平面図であり、６で示した部分が本発明に係わる透光性電極である。 (Example 1)
As an example of the light-transmitting electrode for a light-emitting semiconductor device according to the present invention, an n-type GaN layer, an InGaN layer, a p-type AlGaN layer using AlN as a buffer layer on a sapphire substrate as shown in the sectional view of FIG. An electrode manufactured by forming a first layer 10 made of Au and a second layer 11 made of Ni oxide on a p-type GaN layer of a semiconductor substrate 9 in which p-type GaN layers are sequentially stacked. In FIG. 3, reference numeral 7 denotes a p-side electrode bonding pad, and 8 denotes an n-side electrode. FIG. 2 is a plan view of the light emitting semiconductor element electrode shown in FIG. 3, and a portion indicated by 6 is a translucent electrode according to the present invention.

図２、図３に示した発光半導体素子用透光性電極は、次の手順で作製した。初めに、公知のフォトリソグラフィー技術を用い、ｐ型ＧａＮ層上にＡｕＢｅ／Ａｕ層構造よりなるｐ側電極ボンディング用パッド７を形成した。続いて、公知のフォトリソグラフィー技術及びリフトオフ技術を用いて、ｐ型ＧａＮ層上の透光性電極を形成する領域にのみ、Ａｕからなる第１の層１０およびＮｉの酸化物からなる第２の層１１を形成した。第１の層１０および第２の層１１の形成では、まず、半導体基板９を真空蒸着機に入れ、ｐ型ＧａＮ層上に圧力３×１０-6Ｔｏｒｒにおいて初めにＡｕを２５ｎｍ、続いて同じ真空室内でＮｉを１０ｎｍ蒸着した。ＡｕとＮｉを蒸着した基板は、真空室から取り出した後、通常リフトオフと呼ばれる手順に則って処理し、図２の６で示す形状の薄膜を形成した。このようにしてｐ型ＧａＮ層上には、Ａｕからなる第１の層とＮｉからなる第２の層とからなる薄膜が形成された。この薄膜は金属光沢を呈する暗灰色であり、透光性はほとんど見られなかった。次に、この基板をアニール炉において熱処理した。熱処理は、温度を５５０℃とし、雰囲気ガスとして、１％の酸素ガスを含むアルゴンを流通して、１０分間処理した。取り出した基板の透光性電極６は、青味をおびた暗灰色で、透光性を示していた。なお、この熱処理は電極と半導体とのオーミック接触を得るための熱処理も兼ねていた。 The light-transmitting electrode for a light-emitting semiconductor element shown in FIGS. 2 and 3 was produced by the following procedure. First, a p-side electrode bonding pad 7 having an AuBe / Au layer structure was formed on a p-type GaN layer by using a known photolithography technique. Subsequently, the first layer 10 made of Au and the second layer made of Ni oxide are formed only in a region where the light-transmitting electrode is formed on the p-type GaN layer by using a known photolithography technique and a lift-off technique. Layer 11 was formed. In the formation of the first layer 10 and the second layer 11, first, the semiconductor substrate 9 is put into a vacuum evaporation machine, and first, Au is 25 nm on the p-type GaN layer at a pressure of 3 × 10 −6 Torr, and then the same. Ni was deposited to a thickness of 10 nm in a vacuum chamber. The substrate on which Au and Ni were vapor-deposited was taken out of the vacuum chamber, and then processed according to a procedure generally called lift-off, to form a thin film having a shape shown by 6 in FIG. Thus, a thin film composed of the first layer made of Au and the second layer made of Ni was formed on the p-type GaN layer. This thin film was dark gray having a metallic luster, and hardly any translucency was observed. Next, this substrate was heat-treated in an annealing furnace. The heat treatment was performed at 550 ° C. for 10 minutes by flowing argon containing 1% oxygen gas as an atmosphere gas. The translucent electrode 6 of the substrate taken out was bluish dark gray and translucent. This heat treatment also served as a heat treatment for obtaining ohmic contact between the electrode and the semiconductor.

上記の方法により作製した透光性電極の波長４５０ｎｍの光における透過率は４５％であった。なお、透過率は、上記と同じ透光性電極を透過率測定用の大きさに形成したもので測定した。また、オージェ電子分光（ＡＥＳ）により、透光性電極の深さ方向の成分分析を行った。熱処理の前後で透光性電極の膜厚に大きな変化はなかったが、オージェ電子分光（ＡＥＳ）によってＮｉからなる第２の層に大量の酸素が取り込まれており、Ｎｉの酸化が起きていることが判った。ＡＥＳにより測定した電極の各元素の深さ方向プロファイルを図１に示す。図１に示した上記の電極の組成の深さ方向プロファイルより、第２の層はＮｉと酸素を含むＮｉの酸化物からなり、第１の層は僅かにＮｉを含むＡｕからなり、第１の層と第２の層との界面近傍の領域には、Ｏの濃度が基板方向に向かって小さくなるように組成勾配がつけられた組成勾配領域が存在することがわかる。   The transmissivity of the light-transmitting electrode produced by the above method at a wavelength of 450 nm was 45%. The transmittance was measured using the same translucent electrode as described above formed in a size for transmittance measurement. In addition, component analysis in the depth direction of the translucent electrode was performed by Auger electron spectroscopy (AES). Although there was no significant change in the thickness of the translucent electrode before and after the heat treatment, a large amount of oxygen was taken into the second layer made of Ni by Auger electron spectroscopy (AES), and oxidation of Ni occurred. It turns out. FIG. 1 shows the profile in the depth direction of each element of the electrode measured by AES. According to the depth profile of the composition of the electrode shown in FIG. 1, the second layer is made of an oxide of Ni containing Ni and oxygen, the first layer is made of Au containing Ni slightly, and the first layer is made of Au. It can be seen that in the region near the interface between the first layer and the second layer, there is a composition gradient region in which a composition gradient is applied so that the concentration of O decreases toward the substrate.

また、一般的な薄膜Ｘ線回折（ＸＲＤ）法によってＮｉの酸化物からなる第２の層１１を評価したところ、図４に示すようなスペクトルを示した。ピークの位置から、スペクトルにはＮｉＯの（１１１）、（２００）、（２２０）、（３１１）面からの回折にそれぞれ相当するピーク１２、１４、１６、１８が見られ、第２の層１１はＮｉＯのランダムな方向を向いた結晶からなっていることが判った。また、このスペクトルには、微弱ながらＮｉの（１１１）面からの回折ピーク１５も検出されていた。また、第１の層１０を形成するＡｕ（１１１）、（２２０）面からの回折ピーク１３、１７も見られた。このことから、ＮｉＯの結晶粒の集合体の中に少量のＮｉの結晶粒が混在しているものと考えられる。このことより、第２の層１１はＮｉＯと少量のＮｉよりなることが判った。   When the second layer 11 made of Ni oxide was evaluated by a general thin-film X-ray diffraction (XRD) method, a spectrum as shown in FIG. 4 was shown. From the positions of the peaks, peaks 12, 14, 16, and 18 corresponding to diffraction from the (111), (200), (220), and (311) planes of NiO, respectively, are seen in the spectrum. Was found to be composed of NiO crystals oriented in random directions. In this spectrum, a diffraction peak 15 from the (111) plane of Ni was detected, though weakly. Further, diffraction peaks 13 and 17 from the Au (111) and (220) planes forming the first layer 10 were also observed. From this, it is considered that a small amount of Ni crystal grains are mixed in the aggregate of NiO crystal grains. From this, it was found that the second layer 11 was composed of NiO and a small amount of Ni.

ドライエッチングによってｎ電極を形成する部分のｎ層を露出させ、ｐ側電極の形成に続いて、露出した部分にＡｌよりなるｎ側電極８を形成し、ｎ側電極８のオーミック接触を形成するための熱処理を行った。このようにして電極を形成したウエハを４００μｍ角のチップに切断し、リードフレーム上に載置し結線して発光ダイオードとしたところ、電流２０ｍＡにおける発光出力が８０μＷ、順方向電圧は３．２Ｖを示した。また、２インチφの基板から１６０００個のチップが得られ、発光強度が７６μＷに満たないチップを取り除いたところ、収率は９８％であった。通電発光している状態の透光性電極を顕微鏡により観察したところ、各チップの透光性電極の発光は均一であり、ボールアップによる発光面積の低下は見られなかった。   The n-layer at the portion where the n-electrode is to be formed is exposed by dry etching, and after the formation of the p-side electrode, the n-side electrode 8 made of Al is formed at the exposed portion to form an ohmic contact with the n-side electrode 8. Heat treatment was performed. The wafer on which the electrodes were formed in this manner was cut into 400 μm square chips, mounted on a lead frame and connected to form a light emitting diode. The light emitting output at a current of 20 mA was 80 μW, and the forward voltage was 3.2 V. Indicated. In addition, 16,000 chips were obtained from a substrate having a diameter of 2 inches, and chips with a light emission intensity of less than 76 μW were removed. As a result, the yield was 98%. Observation of the light-transmitting electrode in a state where current was emitted by a microscope revealed that light emission from the light-transmitting electrode of each chip was uniform, and no reduction in light-emitting area due to ball-up was observed.

（比較例１）
実施例１と同じ積層構造を持つ半導体基板に、単層のＡｕ２５ｎｍのみからなる透光性の電極を蒸着装置を用いて形成した。更に、ｐ−ＧａＮ層とのオーミック接触を実現する目的で、アルゴンガス雰囲気中で５５０℃において１０分間熱処理した。熱処理後、透光性電極面は透光性が増したように見えるが、金属光沢を失っていた。この半導体基板から作製された発光ダイオードはボンディング用の電極の直下だけが発光し、透光性の電極面には発光が見られなかった。光学顕微鏡による観察によると、透光性電極として形成したＡｕの薄膜はボール状に凝集しており、薄膜としての連続性を欠いていた。 (Comparative Example 1)
On a semiconductor substrate having the same laminated structure as in Example 1, a single-layer light-transmitting electrode composed of only Au having a thickness of 25 nm was formed using a vapor deposition apparatus. Further, in order to realize ohmic contact with the p-GaN layer, heat treatment was performed at 550 ° C. for 10 minutes in an argon gas atmosphere. After the heat treatment, the translucent electrode surface appeared to have increased translucency, but had lost metallic luster. In the light emitting diode manufactured from this semiconductor substrate, light was emitted only directly below the bonding electrode, and no light emission was observed on the translucent electrode surface. According to observation with an optical microscope, the Au thin film formed as the translucent electrode was agglomerated in a ball shape and lacked continuity as a thin film.

本発明の透光性電極はボールアップを防止した電極として短波長発光素子用のＧａＮ系化合物半導体に有効に利用できる。   INDUSTRIAL APPLICABILITY The translucent electrode of the present invention can be effectively used for a GaN-based compound semiconductor for a short-wavelength light emitting device as an electrode that prevents ball-up.

実施例１で作製した電極のオージェ電子分光による各元素の深さ方向プロファイルを示した図。FIG. 4 is a diagram illustrating a depth direction profile of each element of an electrode manufactured in Example 1 by Auger electron spectroscopy. 実施例１に係わる電極の形状の平面図。FIG. 3 is a plan view of the shape of an electrode according to the first embodiment. 実施例１に係わる電極の積層構造の断面図。FIG. 4 is a cross-sectional view of a laminated structure of the electrode according to the first embodiment. 実施例１に係わる電極の薄膜ＸＲＤスペクトル。4 is a thin-film XRD spectrum of the electrode according to Example 1.

符号の説明Explanation of reference numerals

１・・・Ｎｉのプロファイル
２・・・Ａｕのプロファイル
３・・・Ｏのプロファイル
４・・・Ｇａのプロファイル
５・・・Ｎのプロファイル
６・・・透光性電極
７・・・ｐ側電極用ボンディングパッド
８・・・ｎ側電極
９・・・半導体基板
１０・・・第１の層
１１・・・第２の層
１２・・・ＮｉＯ（１１１）のピーク
１３・・・Ａｕ（１１１）のピーク
１４・・・ＮｉＯ（２００）のピーク
１５・・・Ｎｉ（１１１）のピーク
１６・・・ＮｉＯ（２２０）のピーク
１７・・・Ａｕ（２２０）のピーク
１８・・・ＮｉＯ（３１１）のピーク DESCRIPTION OF SYMBOLS 1 ... Ni profile 2 ... Au profile 3 ... O profile 4 ... Ga profile 5 ... N profile 6 ... Translucent electrode 7 ... p-side electrode Bonding pad 8 n-side electrode 9 semiconductor substrate 10 first layer 11 second layer 12 NiO (111) peak 13 Au (111) Peak 14 of NiO (200) 15 Peak of Ni (111) 16 Peak of NiO (220) 17 Peak 18 of Au (220) 18 NiO (311) Peak of

Claims (12)

ｐ型ＧａＮ系化合物半導体の表面に接して形成され、透光性でかつオーミック接触が得られる、Ａｕ、Ｐｔ、Ｐｄ、Ｎｉからなる群より選ばれた、少なくとも１種類の金属あるいは２種類以上の金属の合金よりなる第１の層と、該第１の層上に形成された、Ｎｉ、Ｃｒ、Ｃｏ、Ｚｎ、Ｍｇよりなる群より選ばれた少なくとも１種類の金属の酸化物を含む、透光性の金属酸化物よりなる第２の層とを有し、該第２の層の表面には前記第１の層の金属は含まれていない発光半導体素子用の透光性電極。 At least one metal or at least two metals selected from the group consisting of Au, Pt, Pd, and Ni, which are formed in contact with the surface of the p-type GaN-based compound semiconductor and provide translucency and ohmic contact. A first layer made of a metal alloy and an oxide of at least one metal selected from the group consisting of Ni, Cr, Co, Zn, and Mg formed on the first layer; A light-transmitting electrode for a light-emitting semiconductor element, comprising: a second layer made of a light-emitting metal oxide, wherein the surface of the second layer does not contain the metal of the first layer. Ａｕよりなる第１の層と、Ｎｉの酸化物を含む第２の層とを有することを特徴とする請求項１記載の透光性電極。 2. The translucent electrode according to claim 1, comprising a first layer made of Au and a second layer containing an oxide of Ni. 前記第２の層がＮｉＯと少量のＮｉである請求項２記載の透明光性電極 3. The transparent light-emitting electrode according to claim 2, wherein said second layer is composed of NiO and a small amount of Ni. 前記第２の層と第１の層との界面近傍の領域において、酸素の組成が第２の層から第１の層に向かって徐々に減少することを特徴とする請求項１乃至３記載の透光性電極。 4. The device according to claim 1, wherein the composition of oxygen gradually decreases from the second layer toward the first layer in a region near an interface between the second layer and the first layer. 5. Translucent electrode. 前記第２の層を構成する金属酸化物の主成分である金属元素が第１の層中に含まれていることを特徴とする請求項１乃至４記載の透光性電極。 The translucent electrode according to claim 1, wherein a metal element that is a main component of a metal oxide forming the second layer is included in the first layer. 前記第１の層の膜厚が１ｎｍ以上５００ｎｍ以下であることを特徴とする請求項１乃至５記載の透光性電極。 6. The translucent electrode according to claim 1, wherein the first layer has a thickness of 1 nm or more and 500 nm or less. 前記第２の層の膜厚が１ｎｍ以上１０００ｎｍ以下であることを特徴とする請求項１乃至６記載の透光性電極。 The translucent electrode according to claim 1, wherein a thickness of the second layer is 1 nm or more and 1000 nm or less. ｐ型ＧａＮ系化合物半導体の表面に接して透光性でオーミック接触が得られる金属薄膜からなる第１の層を形成する第１の工程と、第１の層上に金属からなる第２の層を形成する第２の工程と、これを熱処理することによって第２の層を酸化する第３の工程を有し、酸化後の第２の層の表面には前記第１の層の金属を含まないようにした発光半導体素子用の透光性電極の作製方法。 a first step of forming a first layer made of a metal thin film in contact with the surface of the p-type GaN-based compound semiconductor and capable of obtaining a translucent ohmic contact; and a second layer made of metal on the first layer And a third step of oxidizing the second layer by heat-treating the second layer. The surface of the oxidized second layer contains the metal of the first layer. A method for manufacturing a light-transmitting electrode for a light-emitting semiconductor element which is not required. 前記第１の工程と第２の工程とを同一装置内で連続して行うことを特徴とする請求項８記載の透光性電極の作製方法。 9. The method according to claim 8, wherein the first step and the second step are continuously performed in the same apparatus. 前記第３の工程を酸素を含む雰囲気内で行うことを特徴とする請求項８乃至９記載の透光性電極の作製方法。 10. The method for manufacturing a light-transmitting electrode according to claim 8, wherein the third step is performed in an atmosphere containing oxygen. 前記第３の工程において、熱処理は温度３００℃以上の温度で１分以上行うことを特徴とする請求項８乃至１０記載の透光性電極の作製方法。 The method according to claim 8, wherein in the third step, the heat treatment is performed at a temperature of 300 ° C. or more for 1 minute or more. 請求項１乃至７記載の透光性電極を備えた発光ダイオード。 A light-emitting diode comprising the translucent electrode according to claim 1.
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