JP2009016409A - Semiconductor light emitting element - Google Patents

Semiconductor light emitting element Download PDF

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JP2009016409A
JP2009016409A JP2007173641A JP2007173641A JP2009016409A JP 2009016409 A JP2009016409 A JP 2009016409A JP 2007173641 A JP2007173641 A JP 2007173641A JP 2007173641 A JP2007173641 A JP 2007173641A JP 2009016409 A JP2009016409 A JP 2009016409A
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oxide film
conductive oxide
semiconductor layer
columnar structure
light emitting
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JP5196111B2 (en
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Naoki Musashi
直樹 武藏
Eiji Yoshimoto
英史 吉本
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Nichia Corp
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Nichia Corp
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Abstract

<P>PROBLEM TO BE SOLVED: To provide a semiconductor light emitting element which can be improved in light emission efficiency and can suppress a rise in forward voltage. <P>SOLUTION: Disclosed is the semiconductor light emitting element which has a semiconductor layer and a light-transmissive conductive oxide film provided on the semiconductor layer, the conductive oxide film partially having a columnar structure portion. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

本発明は、半導体発光素子に係わり、より詳細には、半導体層表面に導電性酸化物膜が設けられた半導体発光素子に関する。   The present invention relates to a semiconductor light emitting device, and more particularly to a semiconductor light emitting device in which a conductive oxide film is provided on the surface of a semiconductor layer.

従来から、半導体発光素子として、基板上にｐ型半導体層およびｎ型半導体が積層され、ｐ型およびｎ型の半導体層のそれぞれと電気的に接続する電極が形成された構造が知られている。このような構成の半導体発光素子では、ｐ型の半導体層と電気的に接続する電極として、ｐ型半導体層上全面に透光性材料による電極を形成し、その上に金属電極を形成しており、ｐ型半導体層上の全面電極としては、光の取り出し効率を向上させるため、透明な金属薄膜や、ＩＴＯ、ＺｎＯ、Ｉｎ２Ｏ３、ＳｎＯ２等の導電性酸化物膜が用いられている。ＩＴＯなどの導電性酸化物膜は、柱状構造で形成できることが知られている（例えば、特許文献１〜４）。 2. Description of the Related Art Conventionally, a structure in which a p-type semiconductor layer and an n-type semiconductor are stacked on a substrate and an electrode electrically connected to each of the p-type and n-type semiconductor layers is formed as a semiconductor light emitting device. . In the semiconductor light emitting device having such a configuration, an electrode made of a translucent material is formed on the entire surface of the p-type semiconductor layer as an electrode electrically connected to the p-type semiconductor layer, and a metal electrode is formed thereon. As the entire surface electrode on the p-type semiconductor layer, a transparent metal thin film or a conductive oxide film such as ITO, ZnO, In 2 O 3 or SnO 2 is used to improve the light extraction efficiency. Yes. It is known that a conductive oxide film such as ITO can be formed in a columnar structure (for example, Patent Documents 1 to 4).

また、全面電極に屈折率の異なる粒子を含有させ、光を反射、屈折、あるいは散乱させて素子外部に取り出す構造や、全面電極と半導体層との間の一部に、空隙や屈折率の異なる材料を設ける構造が知られている（例えば、特許文献５〜７）。また、透光性の全面電極と半導体層との間に粒状のオーミック電極を設ける構成も知られている（例えば、特許文献８）。   In addition, the entire surface electrode contains particles having different refractive indexes, and the light is reflected, refracted, or scattered to be extracted from the outside of the device, or a part of the space between the entire surface electrode and the semiconductor layer has a different gap or refractive index. A structure in which a material is provided is known (for example, Patent Documents 5 to 7). In addition, a configuration in which a granular ohmic electrode is provided between a translucent full-surface electrode and a semiconductor layer is also known (for example, Patent Document 8).

特開昭６０−２４０１６６号公報JP-A-60-240166 特開平８−１９４２３０号公報JP-A-8-194230 特開２０００−２２２９４４号公報JP 2000-222944 A 特開２００１−９６６６９号公報JP 2001-96669 A 特表２０００−５０３１６３号公報Special Table 2000-503163 特開２００４−３２７７２９号公報JP 2004-327729 A ＷＯ２００５／０６９３８８WO2005 / 069388 特開２００１−１４４３２３号公報JP 2001-144323 A

しかし、このような従来の半導体発光素子では、導電性酸化物膜の膜全体が一様な構造であるため、膜内で伝播する光を反射や散乱させて素子外部に取り出すことができなかった。さらには、膜全体が柱状構造の導電性酸化物膜を形成すると、密度が小さいために、充分な導電性が得られない傾向にあった。   However, in such a conventional semiconductor light emitting device, since the entire conductive oxide film has a uniform structure, the light propagating in the film cannot be reflected or scattered and extracted outside the device. . Furthermore, when a conductive oxide film having a columnar structure as a whole is formed, the density is low, and sufficient conductivity tends not to be obtained.

また、電極中に屈折率の異なる材料を含有させた構造の場合は、高屈折率の絶縁性材料を用いているために、全面電極中にこのような絶縁性材料を含有させると、電極全体の導電性が悪化するという問題がある。一方、透光性の全面電極と半導体層との間にオーミック電極を設ける構造では、オーミック電極の材料として、全面電極よりも抵抗の低い金属を用いているので、発光領域からの光がオーミック電極で反射されてしまい、素子外部に取り出すことができない。   Also, in the case of a structure in which a material having a different refractive index is included in the electrode, since an insulating material having a high refractive index is used, if such an insulating material is included in the entire surface electrode, the entire electrode There is a problem that the conductivity of the resin deteriorates. On the other hand, in the structure in which the ohmic electrode is provided between the translucent whole surface electrode and the semiconductor layer, a metal having a resistance lower than that of the whole surface electrode is used as the material of the ohmic electrode, so that light from the light emitting region is emitted from the ohmic electrode And cannot be taken out of the device.

上述したような問題を解決するために、本発明の半導体発光素子は、半導体層と、該層上に設けられた透光性の導電性酸化物膜とを有し、導電性酸化物膜は、部分的に柱状構造部を有する。   In order to solve the above-described problems, the semiconductor light emitting device of the present invention has a semiconductor layer and a light-transmitting conductive oxide film provided on the layer, and the conductive oxide film is , Partially having a columnar structure.

本発明の半導体発光素子は、上述の構成に加えて、以下の構成を組み合わせることができる。柱状構造部は、表面に凹凸を有することが好ましい。また、非柱状構造部は、表面が、柱状構造部よりも平坦であることが好ましい。導電性酸化物膜は、半導体層表面に設けられることが好ましい。一方、導電性酸化物膜は、第１の導電性酸化物膜であり、該第１の導電性酸化物膜と半導体層との間に、半導体層と接する第２の導電性酸化物膜が設けられており、半導体層と第２の導電性酸化物膜との間の空隙は、第１の導電性酸化物膜と第２の導電性酸化物膜との間の空隙よりも少ないものとしてもよい。さらに、導電性酸化物膜は、粒状部を有し、柱状構造部は、粒状部から伸びている構造とすることができる。導電性酸化物膜はＩＴＯとすることができ、また、半導体層は窒化物半導体層とすることができる。   The semiconductor light emitting device of the present invention can be combined with the following configurations in addition to the above configuration. The columnar structure portion preferably has irregularities on the surface. Moreover, it is preferable that the surface of the non-columnar structure portion is flatter than that of the columnar structure portion. The conductive oxide film is preferably provided on the surface of the semiconductor layer. On the other hand, the conductive oxide film is a first conductive oxide film, and a second conductive oxide film in contact with the semiconductor layer is interposed between the first conductive oxide film and the semiconductor layer. Provided that the gap between the semiconductor layer and the second conductive oxide film is smaller than the gap between the first conductive oxide film and the second conductive oxide film. Also good. Furthermore, the conductive oxide film can have a granular portion, and the columnar structure portion can have a structure extending from the granular portion. The conductive oxide film can be ITO, and the semiconductor layer can be a nitride semiconductor layer.

本発明の半導体発光素子によれば、柱状構造部において発光領域からの光を乱反射させて素子外部に取り出すことができ、また、導電性酸化物膜の柱状構造部以外の部分では半導体層と良好に密着しており、膜全体として導電性が良好な導電性酸化物膜とできるため、発光効率を向上できると共に、順電圧の上昇を抑制することができる。   According to the semiconductor light emitting device of the present invention, light from the light emitting region can be diffused and extracted outside the device in the columnar structure portion, and the semiconductor oxide layer is good in a portion other than the columnar structure portion of the conductive oxide film. Since the conductive film can be a conductive oxide film having good conductivity as a whole, the luminous efficiency can be improved and an increase in forward voltage can be suppressed.

以下に、本発明の半導体発光素子の実施の形態を図面に基づいて詳細に説明する。   Embodiments of a semiconductor light emitting device according to the present invention will be described below in detail with reference to the drawings.

〔実施形態１〕
半導体発光素子１０１は、図１に示すように、絶縁性の基板１０上に、第１導電型半導体層１１、発光層１２及び第２導電型半導体層１３がこの順に積層されており、第１導電型半導体層１１上に第１電極１４、第２導電型半導体層１３上に第２の電極として、透光性の導電性酸化物膜１５と、金属膜１６とが形成されている。また、本実施形態の半導体発光素子は、図２に示すように、導電性酸化物膜１５が柱状構造部１５ａを部分的に有している。以下、各部材について詳細に説明する。 Embodiment 1
As shown in FIG. 1, the semiconductor light emitting device 101 includes a first conductive semiconductor layer 11, a light emitting layer 12, and a second conductive semiconductor layer 13 stacked in this order on an insulating substrate 10. A light-transmitting conductive oxide film 15 and a metal film 16 are formed as a first electrode 14 on the conductive semiconductor layer 11 and a second electrode on the second conductive semiconductor layer 13. In the semiconductor light emitting device of this embodiment, as shown in FIG. 2, the conductive oxide film 15 partially has a columnar structure portion 15a. Hereinafter, each member will be described in detail.

（導電性酸化物膜１５）
導電性酸化物膜１５は、半導体層から上に向かって伸びる柱状構造部１５ａを有する。柱状構造部１５ａは、それ以外の部分よりも密度が小さく、つまり空隙が多い。このように、密度の異なる柱状構造部１５ａが膜内に存在することで、導電性酸化物膜内を伝播する光を柱状構造部１５ａで好適に乱反射、屈折させ、素子外に取り出すことができる。さらに、柱状構造部１５は、半導体層から上に向かって伸びる柱状の構造であるので、導電性酸化物膜内の光を素子上面から取り出しやすい傾向にある。 (Conductive oxide film 15)
The conductive oxide film 15 has a columnar structure portion 15a extending upward from the semiconductor layer. The columnar structure portion 15a is smaller in density than the other portions, that is, has many voids. As described above, since the columnar structure portions 15a having different densities are present in the film, the light propagating through the conductive oxide film can be suitably irregularly reflected and refracted by the columnar structure portions 15a and taken out of the element. . Further, since the columnar structure portion 15 has a columnar structure extending upward from the semiconductor layer, the light in the conductive oxide film tends to be easily extracted from the upper surface of the element.

また、図１に示すように導電性酸化物膜１５を半導体層１３に接して設けて、柱状構造部１５ａと半導体層１３との間に空隙が存在する素子とすることで、発光領域からの光を好適に、乱反射、屈折させ、導電性酸化物膜１５内に入射させることができ、半導体層と導電性酸化物膜との界面での全反射を抑制して、光の取り出し効率を向上させることができる。   Further, as shown in FIG. 1, the conductive oxide film 15 is provided in contact with the semiconductor layer 13 to form an element in which a gap exists between the columnar structure portion 15 a and the semiconductor layer 13. Light can be diffusely reflected, refracted and incident into the conductive oxide film 15, and total reflection at the interface between the semiconductor layer and the conductive oxide film can be suppressed to improve light extraction efficiency. Can be made.

柱状構造部は、通常、上述のような空隙のある部分では半導体層や他の電極等と接していない。このため、柱状構造部１５ａは半導体層との接触面積が他の部分よりも小さく、導電性に影響を与えやすいが、柱状構造部１５ａ以外の部分は柱状構造部よりも密度の高い緻密な膜であるので、導電性酸化物膜１５全体では良好なオーミック特性の膜とすることができる。柱状構造部１５ａ以外の部分の導電性酸化物膜１５全体に占める割合を大きくすることで、導電性酸化物膜１５の導電性を向上させることができ、一方、柱状構造部１５ａの割合を大きくすると、発光領域からの光を乱反射、屈折可能な領域が増えるので、光取り出し効率を向上させることができる。柱状構造部１５ａと他の部分との好ましい比は、導電性酸化物膜の材料や発光素子に求められる特性等によって決定することができ、例えば半分程度を選択することができる。柱状構造部１５ａは、導電性酸化物膜全体に散在していることが好ましく、これにより、導電性酸化物膜全体で発光領域からの光を乱反射、屈折させて素子外部に取り出すことができ、また、膜全体の導電性を良好なものとできる。導電性の面からは、柱状構造部以外の部分が導電性酸化物膜面内で連続していることが好ましく、つまり、柱状構造部１５ａは島状に点在していることが好ましい。島状の柱状構造部１５ａの大きさは、１０ｎｍ〜１０μｍ程度とすることができ、さらには１００ｎｍ〜数μｍ程度とすることができる。   In general, the columnar structure portion is not in contact with the semiconductor layer, other electrodes, or the like in the portion having the gap as described above. Therefore, the columnar structure portion 15a has a smaller contact area with the semiconductor layer than the other portions and easily affects the conductivity, but the portion other than the columnar structure portion 15a is a dense film having a higher density than the columnar structure portion. Therefore, the entire conductive oxide film 15 can be a film having good ohmic characteristics. By increasing the proportion of the portion other than the columnar structure portion 15a in the entire conductive oxide film 15, the conductivity of the conductive oxide film 15 can be improved, while the proportion of the columnar structure portion 15a is increased. Then, since the region where light from the light emitting region can be irregularly reflected and refracted increases, the light extraction efficiency can be improved. A preferable ratio between the columnar structure portion 15a and the other portion can be determined depending on the material of the conductive oxide film, the characteristics required for the light emitting element, and the like. For example, about half can be selected. The columnar structures 15a are preferably scattered throughout the conductive oxide film, whereby the light from the light emitting region can be irregularly reflected and refracted by the entire conductive oxide film, and extracted outside the device. In addition, the conductivity of the entire film can be improved. From the conductive surface, it is preferable that portions other than the columnar structure portion are continuous in the surface of the conductive oxide film, that is, the columnar structure portions 15a are preferably scattered in an island shape. The size of the island-shaped columnar structure portion 15a can be about 10 nm to 10 μm, and further can be about 100 nm to several μm.

なお、導電性酸化物膜の全膜厚は、特に限定されるものではないが、半導体層側界面近傍での適当な空隙の生成と、比較的低い抵抗と、導電性酸化物膜での光吸収ロス、さらに光取り出し効率を考慮して、例えば、１００〜１０００ｎｍ程度が挙げられる。特に、熱処理する場合には、導電性酸化物膜の膜厚が、１００ｎｍより小さいと、半導体層側界面近傍の空隙が得られない傾向にある。また導電性酸化物膜を低抵抗な膜として機能するには、１０００ｎｍ程度あれば十分であり、１０００ｎｍより大きいと、導電性酸化物膜での光吸収ロスが大きくなり、光取り出し効率が低下してしまうので、１０００ｎｍ以下とする。また、後述の粒子を核として柱状構造部を成長させる方法の場合は、少なくとも粒子よりも大きな膜厚とする。   Note that the total thickness of the conductive oxide film is not particularly limited. However, generation of an appropriate gap near the interface on the semiconductor layer side, relatively low resistance, and light in the conductive oxide film. In consideration of absorption loss and light extraction efficiency, for example, about 100 to 1000 nm may be mentioned. In particular, when heat treatment is performed, if the thickness of the conductive oxide film is smaller than 100 nm, voids near the semiconductor layer side interface tend not to be obtained. Moreover, about 1000 nm is sufficient for the conductive oxide film to function as a low resistance film, and if it is larger than 1000 nm, the light absorption loss in the conductive oxide film increases and the light extraction efficiency decreases. Therefore, it is set to 1000 nm or less. Moreover, in the case of the method of growing a columnar structure part using the below-mentioned particle | grain as a nucleus, it is set as a film thickness larger than a particle | grain at least.

柱状構造部１５ａは、図２に示すように表面に凹凸を有することが好ましい。通常、導電性酸化物膜の表面には台座電極などの接続用の電極や保護膜が設けられるため、このような異なる材料からなる電極や保護膜との界面を凹凸とすることで、界面における全反射を抑制して、柱状構造部１５ａで乱反射、屈折した光を好適に素子外部に取り出すことができる。一方、柱状構造部１５ａ以外の部分は、柱状構造部１５ａよりも平坦な表面とすると、導電性酸化物膜全体として導電性や透光性の良好な膜とできるため、好ましい。このような表面の凹凸は、エッチング等、通常の工程を用いて加工することもできるが、後述する方法を用いて導電性酸化物膜を形成すると、加工を必要とせずに、柱状構造部の表面が凹凸且つ他の部分の表面が平坦な膜を得ることができる。   The columnar structure portion 15a preferably has irregularities on the surface as shown in FIG. Usually, the surface of the conductive oxide film is provided with a connecting electrode such as a pedestal electrode and a protective film. Therefore, by making the interface between the electrode and the protective film made of such different materials uneven, The total reflection is suppressed, and the light irregularly reflected and refracted by the columnar structure portion 15a can be suitably extracted outside the element. On the other hand, it is preferable that the portion other than the columnar structure portion 15a be a surface that is flatter than the columnar structure portion 15a because the entire conductive oxide film can be a film having good conductivity and translucency. Such irregularities on the surface can be processed using a normal process such as etching, but when a conductive oxide film is formed using a method to be described later, the columnar structure portion is not required to be processed. A film having an uneven surface and a flat surface in other portions can be obtained.

導電性酸化物膜１５は、図１に示すように、少なくとも発光層などの発光領域の上に設けることが好ましい。発光領域の上、つまり光取り出し側に柱状構造部を有する導電性酸化物膜を設けることで、好適に光を取り出すことができ、発光素子の出力を向上させることができる。第１導電型半導体層表面にも導電性酸化物膜を形成する場合は、同様に部分的に柱状構造部を有する膜とすると、第１導電型半導体層側からも同様に光を好適に取り出すことができる。   As shown in FIG. 1, the conductive oxide film 15 is preferably provided on at least a light emitting region such as a light emitting layer. By providing a conductive oxide film having a columnar structure portion on the light emitting region, that is, on the light extraction side, light can be preferably extracted and the output of the light emitting element can be improved. When a conductive oxide film is also formed on the surface of the first conductivity type semiconductor layer, similarly, if the film has a columnar structure portion, light is also suitably extracted from the first conductivity type semiconductor layer side as well. be able to.

導電性酸化物膜１５の材料としては、典型的には透光性の材料が選択され、少なくとも柱状構造とそれよりも緻密な構造の両方を形成可能な材料が選択される。具体的には、インジウム及び／またはスズを含む酸化物膜とすることができ、さらには酸化インジウムスズ（ＩＴＯ）とすることが好ましい。   As the material of the conductive oxide film 15, a light-transmitting material is typically selected, and a material capable of forming at least both a columnar structure and a denser structure is selected. Specifically, an oxide film containing indium and / or tin can be used, and indium tin oxide (ITO) is more preferable.

（基板１０）
基板１０は、半導体層構造を成長可能な基板であればよく、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（ＭｇＡｌ２Ｏ４のような絶縁性基板）、ＳｉＣ、Ｓｉ、そして半導体層と格子整合する酸化物基板等を挙げることができる。 (Substrate 10)
The substrate 10 may be any substrate that can grow a semiconductor layer structure. For example, sapphire or spinel (insulating substrate such as MgAl 2 O 4 ) whose main surface is any one of the C-plane, R-plane, and A-plane. , SiC, Si, and an oxide substrate lattice-matched with the semiconductor layer.

（半導体層１１〜１３）
本発明の半導体発光素子における半導体層は、特に限定されるものではなく、シリコン、ゲルマニウム等の元素半導体、ＩＩＩ−Ｖ族、ＩＩ−ＶＩ族、ＶＩ−ＶＩ族等の化合物半導体等が挙げられる。特に、窒化物半導体、なかでも、ＩｎｘＡｌｙＧａ１−ｘ−ｙＮ（０≦ｘ、０≦ｙ、ｘ＋ｙ≦１）等の窒化ガリウム系化合物半導体が好適に用いられる。半導体層は、単層構造でもよいが、ＭＩＳ接合、ＰＩＮ接合又はＰＮ接合を有したホモ構造、ヘテロ構造又はダブルへテロ構造であってもよく、超格子構造や、量子効果が生ずる薄膜を積層した単一量子井戸構造又は多重量子井戸構造であってもよい。また、ｎ型、ｐ型のいずれかの不純物が添加されていてもよい。この半導体層は、例えば、有機金属気相成長法（ＭＯＣＶＤ）、ハイドライド気相成長法（ＨＶＰＥ）、分子線エピタキシャル成長法（ＭＢＥ）等の公知の技術により形成することができる。半導体層の膜厚は特に限定されるものではなく、種々の膜厚のものを適用することができる。 (Semiconductor layers 11-13)
The semiconductor layer in the semiconductor light emitting device of the present invention is not particularly limited, and examples thereof include elemental semiconductors such as silicon and germanium, and compound semiconductors such as III-V group, II-VI group, and VI-VI group. In particular, a nitride semiconductor, in particular, a gallium nitride-based compound semiconductor such as In x Al y Ga 1-xy N (0 ≦ x, 0 ≦ y, x + y ≦ 1) is preferably used. The semiconductor layer may be a single layer structure, but may be a homo structure, a hetero structure or a double hetero structure having a MIS junction, a PIN junction or a PN junction, and a superlattice structure or a thin film generating a quantum effect is laminated. It may be a single quantum well structure or a multiple quantum well structure. Further, either n-type or p-type impurities may be added. This semiconductor layer can be formed by a known technique such as metal organic chemical vapor deposition (MOCVD), hydride vapor deposition (HVPE), molecular beam epitaxy (MBE), or the like. The thickness of the semiconductor layer is not particularly limited, and various thicknesses can be applied.

通常、このような半導体層により、半導体発光素子、例えば、ＬＥＤ、レーザーダイオード等の当該分野で公知の素子が構成されている。具体的には、図１に示すように、第１導電型半導体層１１、発光層１２、第２導電型半導体層１３がこの順に積層され、第１導電型及び第２導電型半導体層にそれぞれ電極が接続されて構成される。なお、第１導電型とはｎ型又はｐ型、第２導電型とはｐ型又はｎ型を意味する。また、上述の導電性酸化物膜は、少なくともｐ型半導体層上に略全面を覆う全面電極として形成されていることが好ましい。導電性酸化物膜は、ｎ型半導体層に形成されていてもよく、さらにｐ型半導体層及びｎ型半導体層の双方の上に形成されていてもよい。   In general, such a semiconductor layer constitutes a semiconductor light emitting element, for example, an element known in the art such as an LED or a laser diode. Specifically, as shown in FIG. 1, a first conductive type semiconductor layer 11, a light emitting layer 12, and a second conductive type semiconductor layer 13 are stacked in this order, and the first conductive type and the second conductive type semiconductor layer are respectively stacked. It is configured with electrodes connected. The first conductivity type means n-type or p-type, and the second conductivity type means p-type or n-type. The conductive oxide film described above is preferably formed as a full-surface electrode that covers substantially the entire surface on at least the p-type semiconductor layer. The conductive oxide film may be formed on the n-type semiconductor layer, and may be formed on both the p-type semiconductor layer and the n-type semiconductor layer.

なお、半導体層は、表面を凹凸加工して、素子内の光を取り出しやすくすることもできるが、本実施形態では、部分的に柱状構造部を有する導電性酸化物膜を半導体層表面に設けているので、半導体層表面を凹凸にしなくても光取り出し効率を向上可能である。また、半導体層表面を凹凸加工すると、半導体層の抵抗が増大する傾向にあるため、半導体層の表面は平坦であることが好ましい。   Note that although the surface of the semiconductor layer can be roughened to make it easier to extract light from the element, in this embodiment, a conductive oxide film partially having a columnar structure is provided on the surface of the semiconductor layer. Therefore, the light extraction efficiency can be improved without making the surface of the semiconductor layer uneven. In addition, since the resistance of the semiconductor layer tends to increase when the unevenness of the semiconductor layer surface is processed, the surface of the semiconductor layer is preferably flat.

また、本実施形態の半導体発光素子では、成長用の絶縁性基板上に半導体層を積層し、その一部を除去して同一面側にｐ電極及びｎ電極を形成しているが、成長用の基板を除去する、または導電性の基板を用いる等して、ｐ電極とｎ電極を半導体層構造の対向面にそれぞれ設けた素子とすることもできる。この場合、上述の導電性酸化物膜は、少なくとも光取り出し側の電極として設けることが好ましい。   In the semiconductor light emitting device of this embodiment, a semiconductor layer is stacked on a growth insulating substrate, and a part thereof is removed to form a p-electrode and an n-electrode on the same surface side. By removing the substrate, or using a conductive substrate, an element in which the p electrode and the n electrode are provided on the opposing surfaces of the semiconductor layer structure can be obtained. In this case, the above-described conductive oxide film is preferably provided as at least an electrode on the light extraction side.

（第１の電極１４、金属膜１６）
第１の電極１４、及び導電性酸化物膜上に形成される金属膜１６は、その種類及び形態は特に限定されるものではなく、通常、電極として用いられるものであればどのようなものでも使用することができる。なかでも、抵抗が低いものが好ましく、具体的には、Ｗ、Ｒｈ、Ａｇ、Ｐｔ、Ｐｄ、Ａｌ、Ｔｉ等の単層膜又は積層膜又は合金が挙げられる。さらに、金属膜１６は、導電性酸化物膜、特に、ＩＴＯ膜との密着性が良好なものが好ましく、具体的には、Ｗ、Ｒｈ、Ｐｔ、Ｔｉ、Ａｕの単層膜又は積層膜が好ましい。また、この金属膜は、半田により接着され又はワイヤボンディングされた台座電極等として機能し得るものであることが好ましい。なお、第１の電極１４と金属膜１６は、その種類、積層構造、膜厚等が異なっていてもよいし、同じでもよい。双方とも同じ金属膜が形成されていれば、製造工程が簡略化され、結果的に安価で信頼性の高い半導体発光素子が得られる。導電性酸化物膜が、ｐ型半導体層及びｎ型半導体層の双方上に形成されている場合の金属膜についても同様である。 (First electrode 14, metal film 16)
The type and form of the first electrode 14 and the metal film 16 formed on the conductive oxide film are not particularly limited, and any metal film can be used as long as it is normally used as an electrode. Can be used. Among them, those having low resistance are preferable, and specific examples include single-layer films or laminated films or alloys of W, Rh, Ag, Pt, Pd, Al, Ti, and the like. Further, the metal film 16 is preferably a conductive oxide film, particularly one having good adhesion to the ITO film. Specifically, a single layer film or a laminated film of W, Rh, Pt, Ti, Au is used. preferable. Moreover, it is preferable that this metal film is a thing which can function as a base electrode etc. which were adhere | attached with solder or wire-bonded. Note that the first electrode 14 and the metal film 16 may be different in type, laminated structure, film thickness, or the like. If the same metal film is formed on both, the manufacturing process is simplified, and as a result, an inexpensive and highly reliable semiconductor light emitting device can be obtained. The same applies to the metal film in the case where the conductive oxide film is formed on both the p-type semiconductor layer and the n-type semiconductor layer.

（製造方法）
本実施形態の半導体発光素子の製造方法は、特に限定されるものではなく、上述のような部分的に柱状構造部を有する導電性酸化物膜が形成できる方法であればよい。例えば、柱状構造の導電性酸化物膜または緻密な導電性酸化物膜のいずれか一方を部分的に形成後、他方を形成する方法が挙げられる。また、以下に説明するような方法で導電性酸化物膜を形成すると、部分的に柱状構造部を有する導電性酸化物膜を簡便に得ることができる。 (Production method)
The method for manufacturing the semiconductor light emitting device of this embodiment is not particularly limited as long as it is a method capable of forming a conductive oxide film having a partially columnar structure as described above. For example, after forming either one of the columnar structure conductive oxide film or the dense conductive oxide film, the other is formed. In addition, when a conductive oxide film is formed by a method described below, a conductive oxide film partially having a columnar structure can be easily obtained.

まず、成長用の基板１０上に、第１導電型半導体層１１、発光層１２、第２導電型半導体層１３を順に形成し、各半導体層の一部を除去して第１導電型半導体層１１を露出させる。   First, the first conductive semiconductor layer 11, the light emitting layer 12, and the second conductive semiconductor layer 13 are formed in this order on the growth substrate 10, and a part of each semiconductor layer is removed to remove the first conductive semiconductor layer. 11 is exposed.

次に、図３（ａ）に示すように、第２導電型半導体層１３の表面に、部分的に粒子３０を付着させる。粒子３０を部分的に付着させる方法としては、例えば、粒子を大気中などに霧状に拡散させ、沈着させて半導体層表面に付着させる方法、揮発性の溶媒と粒子とを含む溶液を塗布し、その後で溶媒を揮発させる方法等が挙げられる。このような方法において、粒子の分布を調整して半導体層表面の粒子付着領域の比率を調整するためには、例えば、粒子を霧状に拡散させる方法では、粒子が拡散されてから半導体層に沈着するまでの距離によって調整できると考えられ、また、粒子を含む溶液を塗布する方法では、溶媒や粒子の材料、粒子のサイズ、界面活性剤の添加の有無などによって調整できると考えられる。   Next, as shown in FIG. 3A, the particles 30 are partially attached to the surface of the second conductivity type semiconductor layer 13. Examples of the method for partially attaching the particles 30 include a method in which particles are diffused in the form of a mist in the atmosphere and deposited and deposited on the surface of the semiconductor layer, or a solution containing a volatile solvent and particles is applied. Then, a method of volatilizing the solvent is mentioned. In such a method, in order to adjust the particle distribution and adjust the ratio of the particle adhesion region on the surface of the semiconductor layer, for example, in the method of diffusing particles in a mist form, the particles are diffused and then applied to the semiconductor layer. It is considered that it can be adjusted by the distance until deposition, and in the method of applying a solution containing particles, it can be adjusted by the solvent, the material of the particles, the size of the particles, the presence or absence of addition of a surfactant, and the like.

そして、第２導電型半導体層１３表面に導電性酸化物膜を成膜する。ここで、第２導電型半導体層１３表面には、粒子を有する領域と、粒子のない、粒子から露出された領域とが混在しているが、導電性酸化物膜は両方の領域を覆うように成膜する。成膜方法は、粒子のない半導体層表面に成膜したときに、非柱状構造、好ましくは柱状構造よりも密度の高い緻密な構造を成長可能な方法を選択する。このようにして成膜すると、図３（ｂ）に示すように、粒子３０から露出した半導体層１３表面では緻密な非柱状構造で成長させ、一方、粒子３０が付着された領域では、粒子３０を核として柱状構造を成長させることができる。これにより、１度の成膜で、柱状構造部１５ａを部分的に有する導電性酸化物膜１５を得ることができる。このような方法によると、導電性酸化物膜１５の柱状構造部１５ａは、図３（ｂ）に示すように、粒子が複数集まった粒状部から光取り出し側に伸びた形状で得られる。   Then, a conductive oxide film is formed on the surface of the second conductivity type semiconductor layer 13. Here, on the surface of the second conductive type semiconductor layer 13, a region having particles and a region having no particles and exposed from the particles are mixed, but the conductive oxide film covers both regions. The film is formed. As the film formation method, a method is selected that can grow a non-columnar structure, preferably a dense structure having a higher density than the columnar structure, when the film is formed on the surface of the semiconductor layer without particles. When the film is formed in this manner, as shown in FIG. 3B, the surface of the semiconductor layer 13 exposed from the particles 30 is grown with a dense non-columnar structure, while in the region where the particles 30 are attached, the particles 30 are grown. A columnar structure can be grown with nuclei. Thereby, the conductive oxide film 15 partially having the columnar structure portion 15a can be obtained by one film formation. According to such a method, the columnar structure portion 15a of the conductive oxide film 15 is obtained in a shape extending from the granular portion where a plurality of particles gather to the light extraction side, as shown in FIG.

その後、第１導電型半導体層１１上に第２の電極１４、導電性酸化物膜１５上に台座電極として金属膜１６をそれぞれ形成し、ボンディングワイヤ等と接続する部分を除いて保護膜（図示せず）を形成して、本実施形態の半導体発光素子を得ることができる。   Thereafter, a second electrode 14 is formed on the first conductive type semiconductor layer 11 and a metal film 16 is formed as a pedestal electrode on the conductive oxide film 15, and a protective film (see FIG. The semiconductor light emitting device of this embodiment can be obtained.

このような方法によると、異なる条件で複数回成膜する必要がないため、製造工程が簡略化されて好ましい。また、典型的には、得られる柱状構造部は、粒状部と半導体層との間には空隙が存在し、表面がその柱状構造に対応した凹凸形状であるので、加工等の工程を必要とせずに、柱状構造部の表面が凹凸で他の部分の表面が平坦な導電性酸化物膜を得ることができる。   Such a method is preferable because the manufacturing process is simplified because it is not necessary to form a film a plurality of times under different conditions. In addition, typically, the obtained columnar structure portion has a gap between the granular portion and the semiconductor layer, and the surface has an uneven shape corresponding to the columnar structure, so that a process such as processing is required. In addition, it is possible to obtain a conductive oxide film in which the surface of the columnar structure is uneven and the surface of the other part is flat.

上述の方法において、導電性酸化物膜１５は、半導体層表面に非柱状構造、好ましくは柱状構造よりも密度の高い緻密な構造を成長可能な方法で形成され、このような方法であれば、当該分野で公知の方法を選択することができる。また、形成する導電性酸化物膜１５は、少なくとも粒子３０よりも大きい膜厚とすることで、粒子３０を核として柱状構造を成長させることができるため、その膜厚としては粒子３０の大きさ以上が選択され、具体的には、粒子３０の大きさの２倍以上とすることが好ましい。   In the above-described method, the conductive oxide film 15 is formed on the surface of the semiconductor layer by a method capable of growing a non-columnar structure, preferably a dense structure having a higher density than the columnar structure. Methods known in the art can be selected. In addition, since the conductive oxide film 15 to be formed has a thickness that is at least larger than that of the particle 30, a columnar structure can be grown using the particle 30 as a nucleus. The above is selected, and specifically, it is preferably set to be twice or more the size of the particle 30.

また、半導体層に付着させる粒子としては、導電性の材料を用いると、発光素子の駆動時における順電圧の増大を防止することができる。さらには、導電性酸化物膜と同じ材料とすることが好ましく、例えば、導電性酸化物膜をＩＴＯとする場合は粒子もＩＴＯとすることが好ましい。また、粒子の大きさは、少なくとも導電性酸化物膜の膜厚よりも小さいものが選択され、具体的には、その直径が約１０ｎｍ以上、約１００ｎｍ以下が好ましく、さらには約５０ｎｍ以下が好ましい。このようにサイズの小さい粒子を用いると、複数の粒子が集まって島状の粒状部を形成しやすく、つまり、島状の柱状構造部を形成しやすい。   In addition, when a conductive material is used as the particles attached to the semiconductor layer, an increase in forward voltage during driving of the light-emitting element can be prevented. Furthermore, it is preferable to use the same material as the conductive oxide film. For example, when the conductive oxide film is ITO, the particles are also preferably ITO. The particle size is selected to be at least smaller than the thickness of the conductive oxide film. Specifically, the diameter is preferably about 10 nm or more and about 100 nm or less, more preferably about 50 nm or less. . When particles having such a small size are used, a plurality of particles are easily collected to form an island-shaped granular portion, that is, an island-shaped columnar structure portion is easily formed.

〔実施の形態２〕
本実施形態の半導体発光素子を、図４に示す。図４に示すように、半導体発光素子１０２は、基板１０上に、第１導電型半導体層１１、発光層１２及び第２導電型半導体層１３がこの順に積層されており、第１導電型半導体層１１上に第１電極１４、第２導電型半導体層１３上に、部分的に柱状構造部を有する第１及び第２の導電性酸化物膜１５、４０、及び金属膜１６が形成されている。第１及び第２の導電性酸化物膜１５、４０は透光性であり、図５に示すように、第２の導電性酸化物膜４０は、第１の導電性酸化物膜１５よりも柱状構造部の比率が小さく、密度の高い緻密な膜の比率が大きい。ここで、実施の形態１と同じ部材には同じ符号を付与しており、実施の形態１と同様のものを用いることができる。 [Embodiment 2]
A semiconductor light emitting device of this embodiment is shown in FIG. As shown in FIG. 4, the semiconductor light emitting device 102 includes a first conductive semiconductor layer 11, a light emitting layer 12, and a second conductive semiconductor layer 13 stacked in this order on a substrate 10. A first electrode 14 is formed on the layer 11, and first and second conductive oxide films 15 and 40 and a metal film 16 partially having a columnar structure are formed on the second conductive semiconductor layer 13. Yes. The first and second conductive oxide films 15 and 40 are translucent, and the second conductive oxide film 40 is more than the first conductive oxide film 15 as shown in FIG. The ratio of the columnar structure portion is small, and the ratio of the dense film having a high density is large. Here, the same reference numerals are given to the same members as those in the first embodiment, and the same members as those in the first embodiment can be used.

実施の形態２の半導体発光素子は、半導体層１３と第１導電性酸化物膜１５との間に第２の導電性酸化物膜４０を設けている点で、実施の形態１の素子と異なる。第２の導電性酸化物膜４０も、第１の導電性酸化物膜１５と同様に、部分的に柱状構造部４０ａを有するが、膜全体に対する柱状構造部の割合は、第１の導電性酸化物膜１５よりも小さい。つまり、膜全体の密度の平均は、第２の導電性酸化物膜４０が第１の導電性酸化物膜１５よりも大きく、また、第１の導電性酸化物膜１５と第２の導電性酸化物膜４０との間の空隙よりも、第２の導電性酸化物膜４０と半導体層１３との間の空隙の方が少ない。このため、実施の形態１と比較して、導電性酸化物膜と半導体層との接触面積を大きくすることができ、また、優れた導電性の膜とでき、素子１０２の順電圧を低減させることができる。一方、光出力向上の点からは、実施の形態１の素子のように、柱状構造部を多く有する導電性酸化物膜を半導体層に接して設けると、導電性酸化物膜と半導体層との界面における全反射を効率的に抑制でき、光取り出し効率をさらに向上できるので、好ましい。   The semiconductor light emitting device of the second embodiment is different from the device of the first embodiment in that a second conductive oxide film 40 is provided between the semiconductor layer 13 and the first conductive oxide film 15. . Similarly to the first conductive oxide film 15, the second conductive oxide film 40 also has a columnar structure portion 40a, but the ratio of the columnar structure portion to the entire film is the first conductive structure. It is smaller than the oxide film 15. In other words, the average density of the entire film is larger in the second conductive oxide film 40 than in the first conductive oxide film 15, and the first conductive oxide film 15 and the second conductivity. There are fewer air gaps between the second conductive oxide film 40 and the semiconductor layer 13 than there are air gaps between the oxide film 40. Therefore, as compared with Embodiment Mode 1, the contact area between the conductive oxide film and the semiconductor layer can be increased, and an excellent conductive film can be obtained, so that the forward voltage of the element 102 is reduced. be able to. On the other hand, from the viewpoint of improving the light output, when a conductive oxide film having many columnar structures is provided in contact with the semiconductor layer as in the element of Embodiment 1, the conductive oxide film and the semiconductor layer It is preferable because total reflection at the interface can be efficiently suppressed and the light extraction efficiency can be further improved.

このような２層の導電性酸化物膜は、まず、半導体層１３上に、柱状構造部の比率が比較的小さい第２の導電性酸化物膜４０を形成し、その上に第２の導電性酸化物膜４０よりも柱状構造部の比率が大きい第１の導電性酸化物膜１５を形成することで、得ることができる。柱状構造部の比率の調整は、例えば上述の粒子を用いる方法においては、粒子のバラツキを制御して調整する方法が考えられる。第１の導電性酸化物膜１５と第２の導電性酸化物膜４０は、同一材料で形成すると、密着性を良好なものとでき、また、屈折率が同程度であることで、２つの膜の界面における全反射を抑制することができる。   In such a two-layer conductive oxide film, first, the second conductive oxide film 40 having a relatively small ratio of the columnar structure portion is formed on the semiconductor layer 13, and the second conductive oxide film is formed thereon. It can be obtained by forming the first conductive oxide film 15 in which the ratio of the columnar structure portion is larger than that of the conductive oxide film 40. As for the adjustment of the ratio of the columnar structure, for example, in the method using the above-described particles, a method of adjusting by adjusting the variation of the particles can be considered. When the first conductive oxide film 15 and the second conductive oxide film 40 are formed of the same material, the adhesion can be improved and the refractive index is approximately the same. Total reflection at the interface of the film can be suppressed.

〔実施の形態３〕
実施の形態３の半導体発光素子は、実施の形態２の素子と同様に、図４に示すように、半導体発光素子１０２は、基板１０上に、第１導電型半導体層１１、発光層１２及び第２導電型半導体層１３がこの順に積層されており、第１導電型半導体層１１上に第１電極１４、第２導電型半導体層１３上に、第２の導電性酸化物膜４０、第１の導電性酸化物膜１５、及び金属膜１６が形成されている。実施の形態１と同じ部材には同じ符号を付与しており、実施の形態１と同様のものを用いることができる。 [Embodiment 3]
As in the element of the second embodiment, the semiconductor light emitting element of the third embodiment has the first conductive semiconductor layer 11, the light emitting layer 12, and the semiconductor light emitting element 102 on the substrate 10, as shown in FIG. The second conductive semiconductor layer 13 is laminated in this order. The first electrode 14 is formed on the first conductive semiconductor layer 11, the second conductive oxide film 40 is formed on the second conductive semiconductor layer 13, and the second conductive oxide film 40 is formed. 1 conductive oxide film 15 and metal film 16 are formed. The same members as those in the first embodiment are given the same reference numerals, and the same members as those in the first embodiment can be used.

本実施形態の素子は、図６に示すように、第２の導電性酸化物膜４０が柱状構造部を有さず、第１の導電性酸化物膜１５のみが部分的に柱状構造部１５ａを有する点で実施の形態２の素子とは異なる。本実施形態の第２の導電酸化物膜４０は、膜全体が、第１の導電性酸化物膜の柱状構造部よりも密度の高い緻密な非柱状構造であるため、半導体層と導電性酸化物膜の接触面積がさらに大きく、実施の形態２の素子よりも順電圧を低減できる。一方、半導体層と導電性酸化物膜との界面の空隙は極めて少なくなるため、光取り出し効率向上の点からは実施の形態２の素子の方が好ましい。   In the element of this embodiment, as shown in FIG. 6, the second conductive oxide film 40 does not have a columnar structure portion, and only the first conductive oxide film 15 is partially a columnar structure portion 15a. This is different from the element of the second embodiment in that Since the second conductive oxide film 40 of the present embodiment has a dense non-columnar structure with a higher density than the columnar structure portion of the first conductive oxide film, the second conductive oxide film 40 and the conductive oxide film The contact area of the material film is larger, and the forward voltage can be reduced as compared with the element of the second embodiment. On the other hand, since the gap at the interface between the semiconductor layer and the conductive oxide film is extremely small, the element of Embodiment 2 is preferable from the viewpoint of improving light extraction efficiency.

このような２層の導電性酸化物膜を形成する方法としては、例えば上述の粒子を用いる方法の場合、まず、半導体層１３上に粒子を付着させずに緻密な導電性酸化物膜を成膜して、第２の導電性酸化物膜４０を形成し、その上に、部分的に粒子を付着させ、第２の導電性酸化物膜４０と同じ条件で導電性酸化物膜を成膜し、部分的に柱状構造を有する第１の導電性酸化物膜１５を形成する方法が考えられる。また、第１の導電性酸化物膜１５と第２の導電性酸化物膜４０は、実施形態２と同様に、同一材料とすることが好ましい。   As a method of forming such a two-layer conductive oxide film, for example, in the case of the method using the above-described particles, first, a dense conductive oxide film is formed on the semiconductor layer 13 without attaching the particles. Then, a second conductive oxide film 40 is formed, and particles are partially deposited thereon, and a conductive oxide film is formed under the same conditions as the second conductive oxide film 40. Then, a method of forming the first conductive oxide film 15 partially having a columnar structure is conceivable. The first conductive oxide film 15 and the second conductive oxide film 40 are preferably made of the same material as in the second embodiment.

（実施例１）
本実施例の半導体発光素子は、絶縁性のサファイア基板にｎ型窒化ガリウム系半導体層、発光層、ｐ型窒化ガリウム系半導体層を順に有し、露出されたｎ型窒化ガリウム系半導体層表面にｎ電極、ｐ型窒化ガリウム系半導体層表面にｐ電極が設けられた素子であり、ｐ電極は、部分的に柱状構造部を有するＩＴＯで構成される透光性の全面電極と、その上の台座電極とからなる。本実施例の素子は、以下の方法で作製される。 Example 1
The semiconductor light emitting device of this example has an n-type gallium nitride semiconductor layer, a light emitting layer, and a p-type gallium nitride semiconductor layer in this order on an insulating sapphire substrate, and is exposed on the exposed n-type gallium nitride semiconductor layer surface. An n-electrode is an element in which a p-electrode is provided on the surface of a p-type gallium nitride based semiconductor layer. It consists of a base electrode. The device of this example is manufactured by the following method.

まず、サファイア基板上に、ｎ型窒化ガリウム系半導体層、発光層、ｐ型窒化ガリウム系半導体層を順に積層し、積層されたｐ型層、発光層、及びｎ型層の一部をエッチングで除去して、ｎ型層の表面を露出させ、その表面に、Ｔｉ、Ｒｈ、Ａｕを積層してｎ電極を形成する。一方、ｐ型層の表面には、ＩＴＯからなり、直径が平均２０〜４０ｎｍの粒子を部分的に付着させ、ＩＴＯ粒子が部分的に設けられたｐ型層上にＩＴＯをスパッタ法により成膜する。このとき、ＩＴＯは、ＩＴＯ粒子から露出したｐ型層表面では柱状構造よりも密度の高い非柱状構造が成長する方法で成膜する。これにより、半導体層表面では緻密な構造が成長すると共に、ＩＴＯ粒子の付着した部分では粒子を核として柱状構造が成長し、部分的に柱状構造部を有する導電性酸化物膜が形成される。その後、導電性酸化物膜上にＴｉ、Ｒｈ、Ａｕを積層して、金属膜を台座電極として形成し、さらにＳｉＯ２からなる保護膜（図示せず）を形成する。 First, an n-type gallium nitride semiconductor layer, a light emitting layer, and a p-type gallium nitride semiconductor layer are sequentially stacked on a sapphire substrate, and a part of the stacked p-type layer, light-emitting layer, and n-type layer is etched. The n-type layer is removed to expose the surface, and Ti, Rh, and Au are stacked on the surface to form an n-electrode. On the other hand, particles having an average diameter of 20 to 40 nm are partially attached to the surface of the p-type layer, and ITO is formed on the p-type layer on which the ITO particles are partially provided by sputtering. To do. At this time, ITO is formed by a method in which a non-columnar structure having a higher density than the columnar structure grows on the surface of the p-type layer exposed from the ITO particles. As a result, a dense structure grows on the surface of the semiconductor layer, and a columnar structure grows with the particles as nuclei in the portion where the ITO particles are adhered, and a conductive oxide film having a columnar structure portion is formed partially. Thereafter, Ti, Rh, and Au are laminated on the conductive oxide film, a metal film is formed as a pedestal electrode, and a protective film (not shown) made of SiO 2 is formed.

以上のようにして作製した半導体発光素子の断面をＳＴＥＭにより観察すると、本実施例のＩＴＯ膜は、柱状構造部を部分的に有していることが確認でき、柱状構造部は、先に塗布したＩＴＯ粒子と思われる粒状部から上に伸びた形状であることが確認できる。柱状構造部と半導体層との間には空隙が存在しており、柱状構造部ではＩＴＯと半導体層は部分的に接している。一方、柱状構造部以外の部分は、柱状構造部と比較して緻密で平坦な膜であり、半導体層とほぼ全面で接している。ＩＴＯの膜厚は、表面が平坦な非柱状構造部では約１６０ｎｍ、表面に凹凸を有する柱状構造部では１６０ｎｍ〜２５０ｎｍ程度であり、柱状構造部と半導体層との間には数十ｎｍ以下の大きさの空隙が存在している。また、本実施例の半導体発光素子の表面をＳＥＭにより観察すると、柱状構造部表面の凹凸が複数確認できる。これは、数百ｎｍ〜数μｍ程度の大きさの島状の柱状構造部が導電性酸化物膜全体に散在しているためと考えられる。このような断面や表面の観察から、導電性酸化物膜全体に占める柱状構造部の割合は、半分程度か、半分よりもやや大きいと推測できる。   When the cross section of the semiconductor light-emitting device fabricated as described above is observed with a STEM, it can be confirmed that the ITO film of this example has a columnar structure portion, and the columnar structure portion is applied first. It can be confirmed that it is a shape extending upward from the granular portion that seems to be the ITO particles. There is a gap between the columnar structure and the semiconductor layer, and the ITO and the semiconductor layer are in partial contact with each other in the columnar structure. On the other hand, the portion other than the columnar structure portion is a dense and flat film as compared with the columnar structure portion, and is in contact with the semiconductor layer almost entirely. The film thickness of ITO is about 160 nm for a non-columnar structure portion having a flat surface, and about 160 nm to 250 nm for a columnar structure portion having an uneven surface, and is several tens of nm or less between the columnar structure portion and the semiconductor layer. There is a gap of size. Further, when the surface of the semiconductor light emitting device of this example is observed by SEM, a plurality of irregularities on the surface of the columnar structure portion can be confirmed. This is presumably because island-like columnar structures having a size of about several hundred nm to several μm are scattered throughout the conductive oxide film. From the observation of the cross section and the surface, it can be estimated that the ratio of the columnar structure portion in the entire conductive oxide film is about half or slightly larger than half.

（実施例２）
実施例２として、ＩＴＯ粒子を塗布する前にｐ型層表面にＩＴＯ膜を形成する以外は実施例１と同様にして、半導体発光素子を作製する。つまり、実施例２の素子ではＩＴＯ膜が２層形成されており、ｐ型層側のＩＴＯ膜は、柱状構造部を有さず、全面が実施例１の非柱状構造部のような緻密で平坦な膜である。 (Example 2)
As Example 2, a semiconductor light emitting device is fabricated in the same manner as in Example 1 except that an ITO film is formed on the surface of the p-type layer before applying the ITO particles. That is, in the element of Example 2, two ITO films are formed, and the ITO film on the p-type layer side does not have a columnar structure, and the entire surface is dense like the non-columnar structure of Example 1. It is a flat film.

（比較例１）
比較例１として、ｐ型層表面に粒子を塗布しない以外は実施例１と同様にして半導体発光素子を作製する。粒子を設けずに導電性酸化物膜を成長させると、実施例１の非柱状構造部のような平坦な膜がｐ型層全面に形成される。 (Comparative Example 1)
As Comparative Example 1, a semiconductor light emitting device is fabricated in the same manner as in Example 1 except that particles are not applied to the p-type layer surface. When the conductive oxide film is grown without providing particles, a flat film like the non-columnar structure portion of Example 1 is formed on the entire surface of the p-type layer.

実施例１、２、及び比較例１の半導体発光素子に２０ｍＡの電流を流して比較すると、比較例１と比較して、光出力が実施例１で約８．４％、実施例２で約１．０％増加する。このように、実施例１、２の素子、特に実施例１の素子とすることで光取り出し効率を向上させることができる。また、順電圧は、実施例１で約１８．８％、実施例２で約０．９％比較例１と比較して増加しており、実施例２のように半導体層と接する側を全面が緻密なＩＴＯ膜とすることで、順電圧の上昇を実施例１と比較して大幅に抑制することができる。   When a current of 20 mA is passed through the semiconductor light emitting devices of Examples 1 and 2 and Comparative Example 1, the optical output is about 8.4% in Example 1 and about 2% in Example 2 compared to Comparative Example 1. Increase by 1.0%. Thus, the light extraction efficiency can be improved by using the elements of Examples 1 and 2, particularly the element of Example 1. Further, the forward voltage is increased by about 18.8% in Example 1 and about 0.9% in Example 2 compared to Comparative Example 1, and the side in contact with the semiconductor layer is entirely exposed as in Example 2. By using a dense ITO film, an increase in forward voltage can be significantly suppressed as compared with the first embodiment.

図１は、本発明の実施の形態１にかかる半導体発光素子を示す模式的な断面図である。FIG. 1 is a schematic cross-sectional view showing a semiconductor light emitting element according to Embodiment 1 of the present invention. 図２は、本発明の実施の形態１の導電性酸化物膜を示す模式的な断面図である。FIG. 2 is a schematic cross-sectional view showing the conductive oxide film according to the first embodiment of the present invention. 図３は、本発明の実施の形態１にかかる半導体発光素子の製造方法を説明するための模式的な断面図である。FIG. 3 is a schematic cross-sectional view for explaining the method for manufacturing the semiconductor light emitting element according to the first embodiment of the present invention. 図４は、本発明の実施の形態２及び３にかかる半導体発光素子を示す模式的な断面図である。FIG. 4 is a schematic cross-sectional view showing the semiconductor light emitting device according to the second and third embodiments of the present invention. 図５は、本発明の実施の形態２の導電性酸化物膜を示す模式的な断面図である。FIG. 5 is a schematic cross-sectional view showing a conductive oxide film according to Embodiment 2 of the present invention. 図６は、本発明の実施の形態３の導電性酸化物膜を示す模式的な断面図である。FIG. 6 is a schematic cross-sectional view showing a conductive oxide film according to Embodiment 3 of the present invention.

符号の説明Explanation of symbols

１０ 基板
１１ 第１導電型半導体層
１２ 発光層
１３ 第２導電型半導体層
１４ 第１の電極
１５ 導電性酸化物膜
１６ 金属膜
３０ 粒子
４０ 第２の導電性酸化物膜
１５ａ、４０ａ 柱状構造部
１０１、１０２ 半導体発光素子 DESCRIPTION OF SYMBOLS 10 Substrate 11 1st conductivity type semiconductor layer 12 Light emitting layer 13 2nd conductivity type semiconductor layer 14 1st electrode 15 Conductive oxide film 16 Metal film 30 Particle | grain 40 2nd conductive oxide film 15a, 40a Columnar structure part 101, 102 Semiconductor light emitting device

Claims (8)

半導体層と、該層上に設けられた透光性の導電性酸化物膜とを有し、
前記導電性酸化物膜は、部分的に柱状構造部を有する半導体発光素子。 A semiconductor layer and a light-transmitting conductive oxide film provided on the layer;
The conductive oxide film is a semiconductor light emitting device having a columnar structure partly. 前記柱状構造部は、表面に凹凸を有する請求項１記載の半導体発光素子。   The semiconductor light emitting element according to claim 1, wherein the columnar structure portion has irregularities on a surface thereof. 前記非柱状構造部は、表面が、前記柱状構造部よりも平坦である請求項１または２記載の半導体発光素子。   The semiconductor light emitting element according to claim 1, wherein a surface of the non-columnar structure portion is flatter than the columnar structure portion. 前記導電性酸化物膜は、前記半導体層表面に設けられる請求項１乃至３のいずれか１項に記載の半導体発光素子。   4. The semiconductor light emitting element according to claim 1, wherein the conductive oxide film is provided on a surface of the semiconductor layer. 5. 前記導電性酸化物膜は、第１の導電性酸化物膜であり、該第１の導電性酸化物膜と前記半導体層との間に、前記半導体層と接する第２の導電性酸化物膜が設けられており、
前記半導体層と前記第２の導電性酸化物膜との間の空隙は、前記第１の導電性酸化物膜と前記第２の導電性酸化物膜との間の空隙よりも少ない請求項１乃至３のいずれか１項に記載の半導体発光素子。 The conductive oxide film is a first conductive oxide film, and a second conductive oxide film in contact with the semiconductor layer is between the first conductive oxide film and the semiconductor layer. Is provided,
2. The gap between the semiconductor layer and the second conductive oxide film is smaller than the gap between the first conductive oxide film and the second conductive oxide film. 4. The semiconductor light emitting device according to any one of items 1 to 3. 前記導電性酸化物膜は、粒状部を有し、前記柱状構造部は、前記粒状部から伸びている請求項１乃至５のいずれか１項に記載の半導体発光素子。   The semiconductor light-emitting element according to claim 1, wherein the conductive oxide film has a granular portion, and the columnar structure portion extends from the granular portion. 前記導電性酸化物膜はＩＴＯである請求項１乃至６のいずれか１項に記載の半導体発光素子。   The semiconductor light-emitting element according to claim 1, wherein the conductive oxide film is ITO. 前記半導体層は窒化物半導体層である請求項１乃至７のいずれか１項に記載の半導体発光素子。   The semiconductor light emitting element according to claim 1, wherein the semiconductor layer is a nitride semiconductor layer.
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