JP2005268601A - Compound semiconductor light-emitting device - Google Patents

Compound semiconductor light-emitting device Download PDF

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JP2005268601A
JP2005268601A JP2004080415A JP2004080415A JP2005268601A JP 2005268601 A JP2005268601 A JP 2005268601A JP 2004080415 A JP2004080415 A JP 2004080415A JP 2004080415 A JP2004080415 A JP 2004080415A JP 2005268601 A JP2005268601 A JP 2005268601A
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Yoshinobu Ono
善伸 小野
Hisamitsu Abe
寿充 安部
Sadanori Yamanaka
貞則 山中
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Sumitomo Chemical Co Ltd
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    • H01S5/34—Structure or shape of the active region; Materials used for the active region comprising quantum well or superlattice structures, e.g. single quantum well [SQW] lasers, multiple quantum well [MQW] lasers or graded index separate confinement heterostructure [GRINSCH] lasers
    • H01S5/343—Structure or shape of the active region; Materials used for the active region comprising quantum well or superlattice structures, e.g. single quantum well [SQW] lasers, multiple quantum well [MQW] lasers or graded index separate confinement heterostructure [GRINSCH] lasers in AIIIBV compounds, e.g. AlGaAs-laser, InP-based laser
    • H01S5/34333—Structure or shape of the active region; Materials used for the active region comprising quantum well or superlattice structures, e.g. single quantum well [SQW] lasers, multiple quantum well [MQW] lasers or graded index separate confinement heterostructure [GRINSCH] lasers in AIIIBV compounds, e.g. AlGaAs-laser, InP-based laser with a well layer based on Ga(In)N or Ga(In)P, e.g. blue laser
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    • H01L33/00—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
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    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L33/00—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L33/02—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor bodies
    • H01L33/26—Materials of the light emitting region
    • H01L33/30—Materials of the light emitting region containing only elements of Group III and Group V of the Periodic Table
    • H01L33/32—Materials of the light emitting region containing only elements of Group III and Group V of the Periodic Table containing nitrogen
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L33/00—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L33/36—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the electrodes
    • H01L33/40—Materials therefor
    • H01L33/42—Transparent materials
    • H—ELECTRICITY
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    • H01S5/00—Semiconductor lasers
    • H01S5/04—Processes or apparatus for excitation, e.g. pumping, e.g. by electron beams
    • H01S5/042—Electrical excitation ; Circuits therefor
    • H01S5/0421—Electrical excitation ; Circuits therefor characterised by the semiconducting contacting layers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L33/00—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L33/02—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor bodies
    • H01L33/14—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor bodies with a carrier transport control structure, e.g. highly-doped semiconductor layer or current-blocking structure
    • H—ELECTRICITY
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    • H01S2301/00—Functional characteristics
    • H01S2301/17—Semiconductor lasers comprising special layers
    • H01S2301/173—The laser chip comprising special buffer layers, e.g. dislocation prevention or reduction
    • H—ELECTRICITY
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    • H01S5/00—Semiconductor lasers
    • H01S5/30—Structure or shape of the active region; Materials used for the active region
    • H01S5/305—Structure or shape of the active region; Materials used for the active region characterised by the doping materials used in the laser structure
    • H01S5/3095—Tunnel junction

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Abstract

<P>PROBLEM TO BE SOLVED: To improve light extraction efficiency in a compound semiconductor light-emitting device. <P>SOLUTION: An ohmic electrode layer 4 for hole injection is provided in contact with a tunneling contact layer (CTL layer) 38 of a nitride semiconductor layer 3 in a light-emitting diode 10 as a transparent conductive ohmic electrode layer, and further a transparent thin-film layer 5 is provided in contact with the ohmic electrode layer 4 for hole injection. By setting the ohmic electrode layer 4 for hole injection to be an ITO, an electrode having high light transmission efficiency can be composed, thus improving light extraction efficiency. By setting the optical film thickness of the ohmic electrode layer 4 for hole injection to an integer multiple of 1/4 of the emission wavelength, the light extraction efficiency can be improved further. And, by providing the transparent thin-film layer 5, a reflection factor can be reduced further by adjusting an refractive index and a film thickness. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

本発明は、窒化物系化合物半導体を用いた発光素子に関するものである。   The present invention relates to a light emitting device using a nitride compound semiconductor.

近年、窒化物系化合物半導体を利用した発光ダイオードやレーザーダイオードなどの発光素子が実用化されている。中でも発光ダイオードの用途は、ディスプレイや信号から白色光を利用したバックライト、一般照明分野へと広がろうとしており、そのためには発光素子の発光効率の向上が求められている。
Solid State Electronics 43(1999).p2081-4 In recent years, light emitting devices such as light emitting diodes and laser diodes using nitride compound semiconductors have been put into practical use. In particular, the use of light emitting diodes is spreading from displays and signals to backlights using white light and general illumination fields. For this purpose, improvement in light emission efficiency of light emitting elements is required.
Solid State Electronics 43 (1999) .p2081-4

発光効率を向上させるために、光取出し面の側に形成するオーミック電極として従来用いられている金属薄膜に代えて、より光透過性が高く、透明導電膜として知られているスズドープ酸化インジウム（以下、「ＩＴＯ」と称する。）の厚さ３００ｎｍ程度の膜をオーミック電極として利用することが試みられ、ｎ型ＧａＮに対して電子注入用オーミック電極として利用できることが報告されている（例えば、非特許文献１参照。）が、発光効率の向上は十分ではなかった。   In order to improve luminous efficiency, tin-doped indium oxide (hereinafter referred to as a transparent conductive film) is used instead of a metal thin film conventionally used as an ohmic electrode formed on the light extraction surface side, which is known as a transparent conductive film. , Referred to as “ITO”) has been tried to be used as an ohmic electrode, and it has been reported that it can be used as an ohmic electrode for electron injection with respect to n-type GaN (for example, non-patent) However, the improvement in luminous efficiency was not sufficient.

本発明の目的は、光取出し面に透明導電膜からなるオーミック電極を有してなり、発光効率の高い化合物半導体発光素子を提供することにある。   An object of the present invention is to provide a compound semiconductor light-emitting element having an ohmic electrode made of a transparent conductive film on a light extraction surface and having high luminous efficiency.

従来技術における上述の問題を解決するために、オーミック電極としてＩＴＯ等の透明導電膜を用いても発光素子の発光効率が十分ではない原因について本発明者が鋭意検討した結果、発光層から発生した光が透明導電膜により反射され、光の取出し面から出射する光の量が減少することが発光効率が上がらない原因であることを見出し、光の取出し面における反射率を低減させる機能を透明導電膜に備えてなる発光素子の発光効率が高いことを見出し、本発明を完成させるに至ったものである。   In order to solve the above-mentioned problems in the prior art, the present inventors diligently investigated the cause of insufficient light emission efficiency of the light emitting element even when using a transparent conductive film such as ITO as an ohmic electrode. We found that light is reflected by the transparent conductive film and the amount of light emitted from the light extraction surface is the cause of the increase in luminous efficiency, and the function of reducing the reflectance on the light extraction surface is The present inventors have found that the light emitting element provided in the film has high light emission efficiency and have completed the present invention.

さらに、この透明導電膜の膜厚を例えばλ／４（λは発光層から出射された光の波長）に調整したものは、界面での反射率が非常に小さくできるので、さらに光取出し効率が高められる。   Furthermore, when the film thickness of this transparent conductive film is adjusted to, for example, λ / 4 (λ is the wavelength of light emitted from the light emitting layer), the reflectance at the interface can be made very small, so that the light extraction efficiency is further improved. Enhanced.

さらに検討を重ねた結果、上述の透明導電膜にさらに他の材料からなる１層以上の透明性薄膜を積層し、各々の屈折率と層厚とを調整して、反射率を極めて小さくすることにより、透明導電膜を積層していない従来技術のものに比べて、光取出し効率を各段に向上させることができる。   As a result of further studies, one or more transparent thin films made of other materials are laminated on the above transparent conductive film, and the refractive index and layer thickness are adjusted to make the reflectance extremely small. As a result, the light extraction efficiency can be improved in each stage as compared with the conventional technique in which the transparent conductive film is not laminated.

請求項１の発明によれば、発光層とオーミック電極とを有し、前記発光層からの光を光取出し面から素子の外部に出射する化合物半導体発光素子であって、前記発光層に関して光取出し面側にあるオーミック電極が透明導電膜からなり、該透明導電膜の面であって発光層側の面と反対側の面に接して前記光の反射を低減する機能を有する反射率低減層が設けられており、該反射率低減層が１つ以上の透明性薄膜を含んで成っていることを特徴とする化合物半導体発光素子が提案される。   According to invention of Claim 1, it is a compound semiconductor light emitting element which has a light emitting layer and an ohmic electrode, and radiate | emits the light from the said light emitting layer to the exterior of an element from the light extraction surface, Comprising: Light extraction regarding the said light emitting layer An ohmic electrode on the surface side is made of a transparent conductive film, and a reflectance reducing layer having a function of reducing the reflection of the light in contact with the surface of the transparent conductive film opposite to the surface on the light emitting layer side There is proposed a compound semiconductor light emitting device which is provided and the reflectance reducing layer includes one or more transparent thin films.

請求項２の発明によれば、請求項１の発明において、前記反射率低減層が、２つ以上の透明性薄膜を積層してなる層である化合物半導体発光素子が提案される。   According to a second aspect of the present invention, there is proposed a compound semiconductor light emitting device according to the first aspect, wherein the reflectance reducing layer is a layer formed by laminating two or more transparent thin films.

請求項３の発明によれば、請求項１または２の発明において、前記透明導電膜が、その発光層側の面でコンタクト層と接している化合物半導体発光素子が提案される。   According to the invention of claim 3, in the invention of claim 1 or 2, a compound semiconductor light emitting element is proposed in which the transparent conductive film is in contact with the contact layer on the surface on the light emitting layer side.

請求項４の発明によれば、請求項１、２または３の発明において、前記透明導電膜の光学膜厚が、発光波長のｍ／４倍（ただしｍは正の整数）である化合物半導体発光素子が提案される。   According to the invention of claim 4, in the invention of claim 1, 2, or 3, compound semiconductor light emission wherein the optical film thickness of the transparent conductive film is m / 4 times the emission wavelength (where m is a positive integer) An element is proposed.

請求項５の発明によれば、請求項１、２、３または４の発明において、前記透明導電膜が、酸化スズが固溶した酸化インジウムからなる透明導電膜である化合物半導体発光素子が提案される。   According to a fifth aspect of the present invention, there is proposed a compound semiconductor light emitting device according to the first, second, third, or fourth aspect, wherein the transparent conductive film is a transparent conductive film made of indium oxide in which tin oxide is dissolved. The

請求項６の発明によれば、請求項１、２、３、４又は５の発明において、前記透明導電膜と前記各々の透明性薄膜とのいずれの膜においても、膜厚ｄと、屈折率ｎと、発光波長λとの間に、式
ｎ×ｄ＝ｍλ／４（ｍは正の整数）
で示される関係が成り立つ化合物半導体発光素子が提案される。 According to the invention of claim 6, in the invention of claim 1, 2, 3, 4 or 5, the film thickness d and the refractive index in any of the transparent conductive film and each of the transparent thin films. Between n and the emission wavelength λ, the formula n × d = mλ / 4 (m is a positive integer)
There is proposed a compound semiconductor light emitting device in which the relationship shown in FIG.

請求項７の発明によれば、請求項５の発明において、前記透明導電膜の光学膜厚が発光波長の１／２であり、前記反射率低減層が１つの透明性薄膜からなり、透明性薄膜の光学膜厚が発光波長の１／４であり、屈折率が１．８〜２．０の範囲または１．４〜１．６の範囲である化合物半導体発光素子が提案される。   According to the invention of claim 7, in the invention of claim 5, the optical film thickness of the transparent conductive film is ½ of the emission wavelength, and the reflectance reduction layer is made of one transparent thin film, A compound semiconductor light emitting device is proposed in which the optical film thickness of the thin film is 1/4 of the emission wavelength and the refractive index is in the range of 1.8 to 2.0 or in the range of 1.4 to 1.6.

請求項８の発明によれば、請求項５の発明において、前記透明導電膜の光学膜厚が発光波長の１／４であり、前記反射率低減層が２つの透明性薄膜からなり、前記透明導電膜に接する側の透明性薄膜の光学膜厚が発光波長の１／４であり、屈折率が１．４５〜１．６５の範囲であり、前記透明導電膜に接しない側の透明性薄膜の光学膜厚が発光波長の１／４であり、屈折率が１．４〜１．６の範囲である化合物半導体発光素子が提案される。   According to the invention of claim 8, in the invention of claim 5, the optical film thickness of the transparent conductive film is ¼ of the emission wavelength, the reflectance reduction layer is composed of two transparent thin films, and the transparent film The optical film thickness of the transparent thin film on the side in contact with the conductive film is 1/4 of the emission wavelength, the refractive index is in the range of 1.45 to 1.65, and the transparent thin film on the side not in contact with the transparent conductive film A compound semiconductor light emitting device having an optical film thickness of ¼ of the emission wavelength and a refractive index in the range of 1.4 to 1.6 is proposed.

請求項９の発明によれば、請求項５の発明において、前記透明導電膜の光学膜厚が発光波長の１／４であり、前記反射率低減層が２つの透明性薄膜からなり、前記透明導電膜に接する側の透明性薄膜の光学膜厚が発光波長の１／４であり、屈折率が１．８〜２．０の範囲であり、前記透明導電膜に接しない側の透明性薄膜の光学膜厚が発光波長の１／４であり、屈折率が１．４〜１．６の範囲である化合物半導体発光素子が提案される。   According to the invention of claim 9, in the invention of claim 5, the optical film thickness of the transparent conductive film is ¼ of the emission wavelength, the reflectance reduction layer is composed of two transparent thin films, and the transparent film The optical film thickness of the transparent thin film on the side in contact with the conductive film is 1/4 of the emission wavelength, the refractive index is in the range of 1.8 to 2.0, and the transparent thin film on the side not in contact with the transparent conductive film A compound semiconductor light emitting device having an optical film thickness of ¼ of the emission wavelength and a refractive index in the range of 1.4 to 1.6 is proposed.

請求項１０の発明によれば、請求項５の発明において、前記透明導電膜の光学膜厚が発光波長の１／４であり、前記反射率低減層が２つの透明性薄膜からなり、前記透明導電膜に接する側の透明性薄膜の光学膜厚が発光波長の１／４であり、屈折率が１．８〜２．０の範囲であり、前記透明導電膜に接しない側の透明性薄膜の光学膜厚が発光波長の１／４であり、屈折率が１．７〜１．９の範囲である化合物半導体発光素子が提案される。   According to the invention of claim 10, in the invention of claim 5, the optical film thickness of the transparent conductive film is ¼ of the emission wavelength, the reflectance reduction layer is composed of two transparent thin films, and the transparent film The optical film thickness of the transparent thin film on the side in contact with the conductive film is 1/4 of the emission wavelength, the refractive index is in the range of 1.8 to 2.0, and the transparent thin film on the side not in contact with the transparent conductive film A compound semiconductor light emitting device having an optical film thickness of ¼ of the emission wavelength and a refractive index in the range of 1.7 to 1.9 is proposed.

請求項１１の発明によれば、請求項５の発明において、前記透明導電膜の光学膜厚が発光波長の１／４であり、前記反射率低減層が２つの透明性薄膜からなり、前記透明導電膜に接する側の透明性薄膜の光学膜厚が発光波長の１／４であり、屈折率が１．４５〜１．６５の範囲であり、前記透明導電膜に接しない側の透明性薄膜の光学膜厚が発光波長の１／４であり、屈折率が１．１〜１．３の範囲である化合物半導体発光素子が提案される。   According to the invention of claim 11, in the invention of claim 5, the optical film thickness of the transparent conductive film is ¼ of the emission wavelength, the reflectance reduction layer is composed of two transparent thin films, and the transparent film The optical film thickness of the transparent thin film on the side in contact with the conductive film is 1/4 of the emission wavelength, the refractive index is in the range of 1.45 to 1.65, and the transparent thin film on the side not in contact with the transparent conductive film A compound semiconductor light emitting device having an optical film thickness of ¼ of the emission wavelength and a refractive index in the range of 1.1 to 1.3 is proposed.

請求項１２の発明によれば、請求項５の発明において、前記透明導電膜の光学膜厚が発光波長の１／４または３／４であり、前記反射率低減層が２つの透明性薄膜からなり、前記透明導電膜に接する側の透明性薄膜の光学膜厚が発光波長の１／２であり、前記透明導電膜に接しない側の透明性薄膜の光学膜厚が発光波長の１／４であり、屈折率が１．５〜１．７の範囲または１．２〜１．４の範囲である化合物半導体発光素子が提案される。   According to the invention of claim 12, in the invention of claim 5, the optical film thickness of the transparent conductive film is 1/4 or 3/4 of the emission wavelength, and the reflectance reduction layer is formed of two transparent thin films. The optical film thickness of the transparent thin film on the side in contact with the transparent conductive film is ½ of the emission wavelength, and the optical film thickness of the transparent thin film on the side not in contact with the transparent conductive film is ¼ of the emission wavelength. A compound semiconductor light emitting device having a refractive index in the range of 1.5 to 1.7 or 1.2 to 1.4 is proposed.

本発明によれば、光取り出し効率の高い化合物半導体発光素子を実現させることができる。   According to the present invention, a compound semiconductor light emitting device with high light extraction efficiency can be realized.

本発明の化合物半導体発光素子は、発光層とオーミック電極を有し、発光層からの光を光取出し面から素子の外部に出射するようにした化合物半導体発光素子において、該オーミック電極のうち発光層に関し光取出し面側にあるオーミック電極が透明導電膜からなっている。そして、該透明導電膜の面であって発光層側の面と反対側の面は光の反射を低減する機能を有し、この機能は１つ以上の透明性薄膜を含み且つ該面に接するように設けられた反射率低減層により果される。   The compound semiconductor light-emitting device of the present invention has a light-emitting layer and an ohmic electrode, and is a compound semiconductor light-emitting device in which light from the light-emitting layer is emitted from the light extraction surface to the outside of the device. The ohmic electrode on the light extraction surface side is made of a transparent conductive film. The surface of the transparent conductive film opposite to the surface on the light emitting layer side has a function of reducing light reflection, and this function includes one or more transparent thin films and is in contact with the surface. This is achieved by the reflectance reduction layer provided as described above.

本発明の化合物半導体発光素子が有するオーミック電極は、発光層に対して少なくとも光取出し面側と、その反対側に設けられている。そのうち、光取出し面側のオーミック電極が透明導電膜からなる。このオーミック電極として好適な透明導電膜の材質としては、酸化インジウム、酸化スズ（ＳｎＯ2 ）、酸化亜鉛（ＺｎＯ）のいずれか１つを主成分とする金属酸化物を挙げることができ、さらに具体的には、これらの金属酸化物に添加物を加えた、ＩＴＯ、アンチモン（Ｓｂ）ドープＳｎＯ2 、フッ素（Ｆ）ドープＳｎＯ2 、アルミニウム（Ａｌ）ドープＺｎＯ、インジウム（Ｉｎ）ドープＺｎＯ、ガリウム（Ｇａ）ドープＺｎＯ等が好適に用いられる。なかでもＩＴＯは小さな接触抵抗と高い光透過率が得られるので特に好ましい。 The ohmic electrode of the compound semiconductor light emitting device of the present invention is provided at least on the light extraction surface side and on the opposite side with respect to the light emitting layer. Among them, the ohmic electrode on the light extraction surface side is made of a transparent conductive film. Examples of the material of the transparent conductive film suitable as the ohmic electrode include metal oxides mainly composed of any one of indium oxide, tin oxide (SnO 2 ), and zinc oxide (ZnO). Specifically, ITO, antimony (Sb) doped SnO 2 , fluorine (F) doped SnO 2 , aluminum (Al) doped ZnO, indium (In) doped ZnO, gallium (added to these metal oxides) Ga) -doped ZnO or the like is preferably used. Of these, ITO is particularly preferable because it provides a small contact resistance and a high light transmittance.

透明導電膜からなる前記オーミック電極は、発光層側の面とその反対側の面の２つの面を有している。本発明の化合物半導体発光素子は、発光層とは反対側の面に、その面における光の反射を低減する機能を有する反射率低減層を有する。この反射率低減層は、オーミック電極とは異なる物質からなる１つ以上の透明性薄膜を含む。この透明性薄膜を該透明導電膜の該面に接して設けることにより、化合物半導体発光素子の発光効率が向上する。すなわち、透明性薄膜を備えていないことを除き素子構造が同一である従来の化合物半導体発光素子を駆動電圧等を同一とする条件で発光させた場合と比較して、本発明の化合物半導体発光素子は従来のそれより高い光出力（輝度）を示すのである。この反射率低減層を２つ以上の透明性薄膜から構成すると、化合物半導体発光素子の出力が高くなるので、好ましい。   The ohmic electrode made of a transparent conductive film has two surfaces, a surface on the light emitting layer side and a surface on the opposite side. The compound semiconductor light emitting device of the present invention has a reflectance reducing layer having a function of reducing light reflection on the surface opposite to the light emitting layer. The reflectance reduction layer includes one or more transparent thin films made of a material different from the ohmic electrode. By providing this transparent thin film in contact with the surface of the transparent conductive film, the light emission efficiency of the compound semiconductor light emitting device is improved. That is, the compound semiconductor light-emitting element of the present invention is compared with the case where a conventional compound semiconductor light-emitting element having the same element structure except that no transparent thin film is provided is made to emit light under the same driving voltage and the like. Indicates a higher light output (brightness) than that of the prior art. It is preferable that the reflectance reducing layer is composed of two or more transparent thin films because the output of the compound semiconductor light emitting device is increased.

本発明の化合物半導体が、従来のそれより高い出力を示す理由は必ずしも明らかではないが、次のような機構に基くものと思われる。透明導電膜からなるオーミック電極として通常用いられる物質はＩＴＯである。このＩＴＯは２．０という比較的高い屈折率を有するため、化合物半導体発光素子を被覆している外部の樹脂とＩＴＯとの屈折率差あるいは外部の空気とＩＴＯとの屈折率差が大きく、そのためにＩＴＯと空気との界面、あるいは化合物半導体発光素子を被覆している樹脂とＩＴＯとの界面において光が反射し、射出する光の量が少なくなり、発光効率が上がらなかったものと思われる。   The reason why the compound semiconductor of the present invention shows a higher output than that of the conventional semiconductor is not necessarily clear, but is thought to be based on the following mechanism. A material usually used as an ohmic electrode made of a transparent conductive film is ITO. Since this ITO has a relatively high refractive index of 2.0, the refractive index difference between the external resin and the ITO covering the compound semiconductor light emitting element or the refractive index difference between the external air and the ITO is large. It is considered that light was reflected at the interface between ITO and air, or between the resin covering the compound semiconductor light emitting element and ITO, the amount of emitted light was reduced, and the light emission efficiency did not increase.

ここで、透明導電膜からなるオーミック電極の面のうち発光層と反対側の面に接してＩＴＯの屈折率に比較的近くＩＴＯより屈折率の低い反射率低減層を設けることにより、屈折率差の少ないオーミック電極／反射率低減層界面および、屈折率差の少ない反射率低減層／外部空気または樹脂界面が形成され、この結果、これらの界面で反射する光が少なくなるものと考えられる。さらに、透明性薄膜とオーミック電極との界面で反射して発光層側に向かう光と外部に出射する方向の光との干渉、オーミック電極と外部との界面で反射して発光層側に向かう光と外部に出射する方向の光との干渉により、前記２ヶ所で反射する光がさらに減少し、その結果、発光素子から出射する光の量が多くなるものと思われる。   Here, a difference in refractive index is provided by providing a reflectance reducing layer that is in contact with the surface opposite to the light emitting layer of the ohmic electrode made of a transparent conductive film and is relatively close to the refractive index of ITO and lower in refractive index than ITO. It is considered that an ohmic electrode / reflectance reduction layer interface with a small amount and a reflectance reduction layer / external air or resin interface with a small refractive index difference are formed, and as a result, less light is reflected at these interfaces. Furthermore, interference between the light reflected at the interface between the transparent thin film and the ohmic electrode and directed toward the light emitting layer and the light emitted in the direction to the outside, the light reflected at the interface between the ohmic electrode and the external directed toward the light emitting layer It is considered that the light reflected at the two locations is further reduced due to the interference between the light and the light emitted in the direction, and as a result, the amount of light emitted from the light emitting element is increased.

透明導電膜からなるオーミック電極の内部で、発光層から外部に出射する方向に進む光と、発光層から出射した後オーミック電極と透明性薄膜の界面で反射した光とが効率よく干渉して反射光を小さくするように、透明導電膜の光学膜厚（厚さ×屈折率）が発光波長のｍ／４（ｍは正の整数である。）倍であることが好ましい。   Inside the ohmic electrode made of a transparent conductive film, the light traveling in the direction from the light emitting layer to the outside and the light reflected from the interface between the ohmic electrode and the transparent thin film after being emitted from the light emitting layer are efficiently reflected and reflected. In order to reduce light, the optical film thickness (thickness × refractive index) of the transparent conductive film is preferably m / 4 (m is a positive integer) times the emission wavelength.

また、透明性薄膜の内部でも、発光層から外部に出射する方向に進む光と、発光層から出射した後透明性薄膜と外部との界面で反射した光とが干渉して反射光を小さくするように、透明性薄膜の光学膜厚も発光波長のｍ／４（ｍは正の整数である。）倍であることがより好ましい。   Even inside the transparent thin film, the light traveling in the direction from the light emitting layer to the outside and the light reflected from the interface between the transparent thin film and the outside after emitting from the light emitting layer interfere with each other to reduce the reflected light. Thus, the optical film thickness of the transparent thin film is more preferably m / 4 (m is a positive integer) times the emission wavelength.

透明性薄膜を構成する物質は、オーミック電極を構成する物質より屈折率が小さいことが好ましい。オーミック電極を構成する物質としては、通常は屈折率が２．０のＩＴＯが用いられるので、透明性薄膜を構成する物質は、屈折率が２．０以下のものが好ましい。透明性薄膜を構成する物質の屈折率は、透明性薄膜が空気と接しているときは、空気の屈折率が１．０なので１．０以上であり、樹脂と接しているときは、樹脂の屈折率は通常は１．４程度なので、１．４以上が好ましい。   The material constituting the transparent thin film preferably has a smaller refractive index than the material constituting the ohmic electrode. As the material constituting the ohmic electrode, ITO having a refractive index of 2.0 is usually used. Therefore, the material constituting the transparent thin film preferably has a refractive index of 2.0 or less. The refractive index of the material constituting the transparent thin film is 1.0 or more when the transparent thin film is in contact with air, since the refractive index of air is 1.0, and when the transparent thin film is in contact with the resin, Since the refractive index is usually about 1.4, 1.4 or more is preferable.

透明性薄膜を構成する物質としては、具体的には、屈折率が１．９のＳｎＯ2 、屈折率が１．８のＭｇＯ、屈折率が１．４６のＳｉＯ2 、屈折率が１．５９のＬａＦ3 、屈折率が１．２４のＣａＦ2 が挙げられる。 Specifically, the material constituting the transparent thin film is SnO 2 having a refractive index of 1.9, MgO having a refractive index of 1.8, SiO 2 having a refractive index of 1.46, and a refractive index of 1.59. LaF 3 , and CaF 2 having a refractive index of 1.24.

ここで、反射率低減層が１つの透明性薄膜からなる場合は、さらに次の条件を満たすことがさらに好ましい。
すなわち、
ｎ１＝√（ｎ０・ｎｓ）
ｎ１・ｄ１＝λ／４
ｎｏ・ｄｏ＝λ／２
である。ただし、ｎ１、ｄ１はそれぞれ透明性薄膜層の屈折率と膜厚、ｎｏ、ｄｏはそれぞれオーミック電極の屈折率と膜厚、ｎｓは化合物半導体のうちのオーミック電極と接している層を構成する物質の屈折率、ｎ０は外部空気または外部樹脂の屈折率、λは発光波長である。なお、化合物半導体のうちのオーミック電極と接している層が窒化ガリウムからなる場合は、ｎｓは２．４である。 Here, when a reflectance reduction layer consists of one transparent thin film, it is still more preferable to satisfy the following conditions.
That is,
n1 = √ (n0 · ns)
n1 · d1 = λ / 4
no.do = λ / 2
It is. Where n1 and d1 are the refractive index and film thickness of the transparent thin film layer, no and do are the refractive index and film thickness of the ohmic electrode, respectively, and ns is a substance constituting the layer in contact with the ohmic electrode of the compound semiconductor , N0 is the refractive index of external air or external resin, and λ is the emission wavelength. When the layer in contact with the ohmic electrode in the compound semiconductor is made of gallium nitride, ns is 2.4.

オーミック電極がＩＴＯの膜からなり、反射率低減層が樹脂に接する場合には、例えば、透明性薄膜層の屈折率を１．８〜２．０とすることができる。このような物質の例として、透明性薄膜層がＳｎＯ2 、ＳｉＯ2 またはＭｇＯからなる場合が挙げられる。また、オーミック電極がＩＴＯの膜からなり反射率低減層が空気に接する場合には、例えば、透明性薄膜層の屈折率を１．４〜１．６とすることができる。このような物質の例として、透明性薄膜層がＳｉＯ2 またはＬａＦ3 からなる場合が挙げられる。 When the ohmic electrode is made of an ITO film and the reflectance reducing layer is in contact with the resin, for example, the refractive index of the transparent thin film layer can be set to 1.8 to 2.0. Examples of such a material include a case where the transparent thin film layer is made of SnO 2 , SiO 2, or MgO. When the ohmic electrode is made of an ITO film and the reflectance reducing layer is in contact with air, the refractive index of the transparent thin film layer can be set to 1.4 to 1.6, for example. As an example of such a substance, a case where the transparent thin film layer is made of SiO 2 or LaF 3 can be mentioned.

さらに、反射率低減層が２つの透明性薄膜を積層してなる場合は、以下に示す第１〜第３の条件のうちのいずれかの条件を満たすことがさらに好ましい。
すなわち、第１の条件は、
ｎ１／ｎ２＝ｎｏ／√（ｎｓ・ｎ０）
ｎ１・ｄ１＝λ／４
ｎ２・ｄ２＝λ／４
ｎｏ・ｄｏ＝λ／４
である。ただし、ｎ１、ｄ１はそれぞれ、２つの透明性薄膜のうちのオーミック電極に接する側の膜の屈折率と膜厚、ｎ２、ｄ２はそれぞれ、２つの透明性薄膜のうちのオーミック電極に接していない側の膜の屈折率と膜厚、ｎｏ、ｄｏはそれぞれオーミック電極の屈折率と膜厚、ｎｓは化合物半導体のうちのオーミック電極と接している層を構成する物質の屈折率、ｎ０はは外部空気または外部樹脂の屈折率、λは発光波長である。 Furthermore, when the reflectance reduction layer is formed by laminating two transparent thin films, it is more preferable to satisfy any one of the following first to third conditions.
That is, the first condition is
n1 / n2 = no / √ (ns · n0)
n1 · d1 = λ / 4
n2 · d2 = λ / 4
no.do = λ / 4
It is. However, n1 and d1 are the refractive index and film thickness of the film in contact with the ohmic electrode of the two transparent thin films, respectively, and n2 and d2 are not in contact with the ohmic electrode of the two transparent thin films, respectively. The refractive index and film thickness of the side film, no and do are the refractive index and film thickness of the ohmic electrode, ns is the refractive index of the material constituting the layer in contact with the ohmic electrode of the compound semiconductor, and n0 is the external The refractive index of air or external resin, λ is the emission wavelength.

オーミック電極がＩＴＯの膜からなり、反射率低減層が樹脂に接する場合には、例えば、ＩＴＯ膜に接する側の透明性薄膜層の屈折率を１．４５〜１．６５とし、樹脂に接する側の透明性薄膜の屈折率を１．４〜１．６とすることができる。このような例として、ＩＴＯ膜に接する側の透明性薄膜層がＬａＦ3 で樹脂に接する側の透明性薄膜がＳｉＯ2 からなる場合が挙げられる。また、オーミック電極がＩＴＯの膜からなり反射率低減層が空気に接する場合には、例えば、ＩＴＯ膜に接する側の透明性薄膜層の屈折率を１．８〜２．０とし、空気に接する側の透明性薄膜層の屈折率を１．４〜１．６とすることができる。このような物質の例として、ＩＴＯ膜に接する側の透明性薄膜層がＳｎＯ2 で空気に接する側の透明性薄膜層がＳｉＯ2 からなる場合が挙げられる。 When the ohmic electrode is made of an ITO film and the reflectance reducing layer is in contact with the resin, for example, the refractive index of the transparent thin film layer on the side in contact with the ITO film is 1.45 to 1.65, and the side in contact with the resin The refractive index of the transparent thin film can be set to 1.4 to 1.6. As an example, the transparent thin film layer on the side in contact with the ITO film is LaF 3 and the transparent thin film on the side in contact with the resin is made of SiO 2 . When the ohmic electrode is made of an ITO film and the reflectance reducing layer is in contact with air, for example, the refractive index of the transparent thin film layer on the side in contact with the ITO film is set to 1.8 to 2.0 and is in contact with air. The refractive index of the transparent thin film layer on the side can be set to 1.4 to 1.6. As an example of such a substance, there is a case where the transparent thin film layer on the side in contact with the ITO film is SnO 2 and the transparent thin film layer on the side in contact with air is made of SiO 2 .

第２の条件は、
ｎ１＝√（ｎ０・ｎｓ）、 ｎ２＝ｎ１2 ／ｎｏ
ｎ１・ｄ１＝ｍλ／４
ｎ２・ｄ２＝ｍλ／４
ｎｏ・ｄｏ＝ｍλ／４
である。ｎ１、ｎ２、ｎｏ、ｎ０、ｎｓ、ｄ１、ｄ２、λはそれぞれ前記と同じ意味を示す。 The second condition is
n1 = √ (n0 · ns), n2 = n1 2 / no
n1 · d1 = mλ / 4
n2 · d2 = mλ / 4
no.do = mλ / 4
It is. n1, n2, no, n0, ns, d1, d2, and λ each have the same meaning as described above.

オーミック電極がＩＴＯの膜からなり、反射率低減層が樹脂に接する場合には、例えば、ＩＴＯ膜に接する側の透明性薄膜の屈折率を１．８〜２．０とし、樹脂に接する側の透明性薄膜の屈折率を１．７〜１．９とすることができる。このような物質の例として、ＩＴＯ膜に接する側の透明性薄膜がＳｎＯ2 で樹脂に接する側の透明性薄膜がＭｇＯからなる場合が挙げられる。また、オーミック電極がＩＴＯの膜からなり、反射率低減層が空気に接する場合には、例えば、ＩＴＯ膜に接する側の透明性薄膜の屈折率を１．４５〜１．６５とし、空気に接する側の透明性薄膜の屈折率を１．１〜１．３とすることができる。このような物質の例として、ＩＴＯ膜に接する側の透明性薄膜がＬａＦ3 で空気に接する側の透明性薄膜がＣａＦ2 からなる場合が挙げられる。 When the ohmic electrode is made of an ITO film and the reflectance reduction layer is in contact with the resin, for example, the refractive index of the transparent thin film on the side in contact with the ITO film is 1.8 to 2.0, The refractive index of the transparent thin film can be 1.7 to 1.9. As an example of such a substance, there is a case where the transparent thin film on the side in contact with the ITO film is SnO 2 and the transparent thin film on the side in contact with the resin is made of MgO. Further, when the ohmic electrode is made of an ITO film and the reflectance reduction layer is in contact with air, for example, the refractive index of the transparent thin film on the side in contact with the ITO film is 1.45 to 1.65 and in contact with air. The refractive index of the transparent film on the side can be set to 1.1 to 1.3. As an example of such a substance, there is a case where the transparent thin film on the side in contact with the ITO film is LaF 3 and the transparent thin film on the side in contact with air is made of CaF 2 .

第３の条件は、
ｎ２＝ｎｏ・√（ｎ０／ｎｓ）
ｎ１・ｄ１＝λ／４
ｎ２・ｄ２＝λ／２
ｎｏ・ｄｏ＝λ／４ または ３λ／４
である。ｎ１、ｎ２、ｎｏ、ｎ０、ｎｓ、ｄ１、ｄ２、λはそれぞれ前記と同じ意味を示す。 The third condition is
n2 = no · √ (n0 / ns)
n1 · d1 = λ / 4
n2 · d2 = λ / 2
no · do = λ / 4 or 3λ / 4
It is. n1, n2, no, n0, ns, d1, d2, and λ each have the same meaning as described above.

この場合は、オーミック電極に接する側の透明性薄膜の屈折率は任意でよいが、オーミック電極がＩＴＯの膜からなり、反射率低減層が樹脂に接する場合には、例えば、樹脂に接する側の透明性薄膜の屈折率を１．５〜１．７とすることができる。このような物質の例として、樹脂に接する側の透明性薄膜がＬａＦ3 、ＮｄＦ3 からなる場合が挙げられる。また、オーミック電極がＩＴＯの膜からなり、反射率低減層が空気に接する場合には、例えば、空気に接する側の透明性薄膜の屈折率を１．２〜１．４とすることができる。このような物質の例として、空気に接する側の透明性薄膜がＣａＦ2 からなる場合が挙げられる。 In this case, the refractive index of the transparent thin film on the side in contact with the ohmic electrode may be arbitrary, but when the ohmic electrode is made of an ITO film and the reflectance reducing layer is in contact with the resin, for example, The refractive index of the transparent thin film can be set to 1.5 to 1.7. As an example of such a substance, the case where the transparent thin film on the side in contact with the resin is made of LaF 3 or NdF 3 can be mentioned. When the ohmic electrode is made of an ITO film and the reflectance reducing layer is in contact with air, for example, the refractive index of the transparent thin film on the side in contact with air can be set to 1.2 to 1.4. As an example of such a substance, there is a case where the transparent thin film on the side in contact with air is made of CaF 2 .

このような、反射率低減層が１つの透明性薄膜からなる場合の１つの条件、または２つの透明性薄膜からなる場合の３つの条件のいずれかを満たした場合、理論的には反射光がをゼロとすることができる。   In the case where one of the conditions in which the reflectance reduction layer is made of one transparent thin film or the three conditions in the case of two transparent thin films is satisfied, the reflected light is theoretically reduced. Can be zero.

以下、図面を参照して本発明の実施の形態の一例につき詳細に説明する。   Hereinafter, an example of an embodiment of the present invention will be described in detail with reference to the drawings.

図１は、本発明による化合物半導体発光素子の実施の形態の一例を示す層構造図である。図１に示す化合物半導体発光素子は、サファイア基板上に化合物半導体からなる薄膜層が積層されて発光素子が構成されている発光ダイオードの場合の例であり、ｐ型ＧａＮ層の上にトンネリングコンタクト層と透明性薄膜層とを積層する構成とすることにより、窒化物半導体結晶内部からの光をそのｐ層側から効率よく取り出すことができるようにしたものである。   FIG. 1 is a layer structure diagram showing an example of an embodiment of a compound semiconductor light emitting device according to the present invention. The compound semiconductor light emitting device shown in FIG. 1 is an example of a light emitting diode in which a light emitting device is configured by laminating a thin film layer made of a compound semiconductor on a sapphire substrate, and a tunneling contact layer on a p-type GaN layer. And a transparent thin film layer are stacked so that light from inside the nitride semiconductor crystal can be efficiently extracted from the p-layer side.

発光ダイオード（発光素子）１０はサファイア基板１上にＧａＮ低温バッファ層２を設け、ＧａＮ低温バッファ層２の上に発光ダイオード構造の窒化物系半導体エピタキシャル結晶薄膜層を有機金属気相成長法により積層して成長し、これにより、活性層を構成する化合物半導体層（窒化物半導体層）３が形成されている。   A light-emitting diode (light-emitting element) 10 is provided with a GaN low-temperature buffer layer 2 on a sapphire substrate 1, and a nitride-based semiconductor epitaxial crystal thin film layer having a light-emitting diode structure is laminated on the GaN low-temperature buffer layer 2 by metal organic vapor phase epitaxy. Thus, the compound semiconductor layer (nitride semiconductor layer) 3 constituting the active layer is formed.

窒化物半導体層３は、高濃度Ｓｉドープｎ+ −ＧａＮ層３１、Ｓｉドープｎ−ＧａＮ層３２、アンドープＧａＮ層３３、多重量子井戸活性層（ＭＱＷ層）３４、アンドープＧａＮ層３５、Ｍｇドープｎ−Ａｌ0.15Ｇａ0.85Ｎ層３６、Ｍｇドープｐ−ＧａＮ層３７、及びトンネリングコンタクト層（ＣＴＬ層）３８を積層して構成されている。 The nitride semiconductor layer 3 includes a high-concentration Si-doped n + -GaN layer 31, a Si-doped n-GaN layer 32, an undoped GaN layer 33, a multiple quantum well active layer (MQW layer) 34, an undoped GaN layer 35, and an Mg-doped n -Al 0.15 Ga 0.85 N layer 36, Mg-doped p-GaN layer 37, and tunneling contact layer (CTL layer) 38 are stacked.

ここで、発光層であるＭＱＷ層３４は、アンドープＧａＮ層とＩｎＧａＮ層とを交互に５回繰り返して積層した多重量子井戸であり、ＣＴＬ層３８はＳｉドープｎ−ＧａＮ層とＳｉドープｐ型ＩｎＧａＮ層の５回繰り返しから成る層構成とされている。   Here, the MQW layer 34 which is a light emitting layer is a multiple quantum well in which an undoped GaN layer and an InGaN layer are alternately and repeatedly stacked five times, and the CTL layer 38 is a Si-doped n-GaN layer and a Si-doped p-type InGaN. The layer structure is composed of five repetitions of the layer.

サファイア基板１から見て窒化物半導体層３の最上層であるＣＴＬ層３８の上には、ホール注入用オーミック電極層４が形成されている。ここでは、ホール注入用オーミック電極層４としてＩＴＯ膜が電子ビーム蒸着法によりその全面に亘って形成されている。ホール注入用オーミック電極層４の上には透明薄膜層５が形成されている。６、７は取り出し電極である。ここで、ＣＴＬ層３８が窒化物半導体層３からの光を取り出す光取出し側となっており、ＣＴＬ層３８のホール注入用オーミック電極層４側の表面３８Ａが光取出し面となっている。   On the CTL layer 38 which is the uppermost layer of the nitride semiconductor layer 3 when viewed from the sapphire substrate 1, a hole injection ohmic electrode layer 4 is formed. Here, an ITO film is formed over the entire surface of the ohmic electrode layer 4 for hole injection by an electron beam evaporation method. A transparent thin film layer 5 is formed on the hole injection ohmic electrode layer 4. Reference numerals 6 and 7 denote extraction electrodes. Here, the CTL layer 38 is a light extraction side for extracting light from the nitride semiconductor layer 3, and the surface 38A of the CTL layer 38 on the hole injection ohmic electrode layer 4 side is a light extraction surface.

反射率低減層５は反射率低減層として働く層であり、２層以上の透明性薄膜からなる構成が好ましい。図２には、そのような場合の構成の一例の要部が示されている。ここでは、反射率低減層を構成する２つの透明性薄膜５１、５２のうち、オーミック電極４１に接する側の透明性薄膜５１の屈折率と膜厚をそれぞれｎ１、ｄ１、オーミック電極４１に接していない側の透明性薄膜５２の屈折率と膜厚をそれぞれｎ２、ｄ２、オーミック電極４１の屈折率と膜厚をそれぞれｎｏ、ｄｏ、化合物半導体のうちのオーミック電極４１と接している層３０を構成する物質の屈折率をｎｓで示してある。   The reflectance reduction layer 5 is a layer that functions as a reflectance reduction layer, and preferably has a configuration composed of two or more transparent thin films. FIG. 2 shows a main part of an example of the configuration in such a case. Here, the refractive index and film thickness of the transparent thin film 51 on the side in contact with the ohmic electrode 41 out of the two transparent thin films 51 and 52 constituting the reflectance reduction layer are in contact with n1, d1, and the ohmic electrode 41, respectively. The layer 30 in contact with the ohmic electrode 41 of the compound semiconductor is constituted by n2 and d2 respectively for the refractive index and film thickness of the transparent thin film 52 on the non-side, and no and do for the ohmic electrode 41 respectively. The index of refraction of the material is indicated by ns.

このように、発光ダイオード１０の光取出し面側には、ＩＴＯ膜によるホール注入用オーミック電極層４が光透過性で導電性の膜として形成されている構造となっている。しかし、光取出し面と反対側の電極においても、ＩＴＯ透明導電膜を利用することができるものの、これを用いることは必ずしも必須ではなく、接触抵抗の小さな電極であれば適宜利用可能である。   Thus, on the light extraction surface side of the light emitting diode 10, the hole injection ohmic electrode layer 4 made of an ITO film is formed as a light transmissive and conductive film. However, although an ITO transparent conductive film can be used for the electrode opposite to the light extraction surface, it is not always necessary to use it, and any electrode having a small contact resistance can be used as appropriate.

図３には、本発明による発光ダイオードの他の実施の形態を示す層構造図を示した。図３の各部のうち、図１の各部に対応する部分には同一の符号が付されている。図３に示した発光ダイオード（発光素子）２０は、ｐ層側の構造は図１に示した発光ダイオード１０と略同じであるが、サファイア基板１に代えて導電性基板２１を利用し、化合物半導体層３の最下層のｎ+ −ＧａＮ層３１と導電性基板２１との間に光反射層２２を設けた構成となっている点で図１に示した発光ダイオード１０と異なっている。 FIG. 3 is a layer structure diagram showing another embodiment of the light emitting diode according to the present invention. 3 corresponding to those in FIG. 1 are denoted by the same reference numerals. The light-emitting diode (light-emitting element) 20 shown in FIG. 3 has a p-layer side structure that is substantially the same as that of the light-emitting diode 10 shown in FIG. 1, but uses a conductive substrate 21 instead of the sapphire substrate 1 to form a compound. 1 is different from the light-emitting diode 10 shown in FIG. 1 in that a light reflection layer 22 is provided between the n + -GaN layer 31 at the lowest layer of the semiconductor layer 3 and the conductive substrate 21.

光反射層２２は、接着および反射の機能を有する接着／反射層２２１と、透明導電膜からなる電子注入用オーミック電極層２２２との２層構造で、接着／反射層２２１が導電性基板２１に接し、電子注入用オーミック電極層２２２がｎ+ −ＧａＮ層３１に接する構成となっている。図３において、２３はヒートシンク、２４は接着層である。 The light reflection layer 22 has a two-layer structure of an adhesion / reflection layer 221 having an adhesion and reflection function and an ohmic electrode layer 222 for electron injection made of a transparent conductive film. The adhesion / reflection layer 221 is formed on the conductive substrate 21. The ohmic electrode layer 222 for electron injection is in contact with the n + -GaN layer 31. In FIG. 3, 23 is a heat sink and 24 is an adhesive layer.

発光ダイオード２０の構成によれば、窒化物半導体層３から導電性基板２１に向けて放射された光が光反射層２２により反射され光取出し面側に取り出せるので、図１に示した構成の場合に比べて光取り出しの効率をより高くすることができる。   According to the configuration of the light emitting diode 20, the light emitted from the nitride semiconductor layer 3 toward the conductive substrate 21 is reflected by the light reflecting layer 22 and can be extracted to the light extraction surface side. As compared with the above, the light extraction efficiency can be further increased.

図４には、本発明による発光ダイオードの別の実施の形態を示す層構造図を示した。図４に示す発光ダイオード３０は、ｎ型層側から光を取り出す構成となっている点で図３に示した発光ダイオード２０と異なっている。このため、窒化物半導体層３を構成する窒化物半導体薄膜層の積層順序が発光ダイオード２０と発光ダイオード３０とで逆になっているが、発光ダイオード４０はｎ型層側から光を取り出すようになっている点を除き、発光ダイオード３０と同一の機能を有しており、光取出し効率を発光ダイオード３０の場合と同様に向上させることができる。   FIG. 4 is a layer structure diagram showing another embodiment of the light emitting diode according to the present invention. The light emitting diode 30 shown in FIG. 4 is different from the light emitting diode 20 shown in FIG. 3 in that light is extracted from the n-type layer side. For this reason, the stacking order of the nitride semiconductor thin film layers constituting the nitride semiconductor layer 3 is reversed between the light emitting diode 20 and the light emitting diode 30, but the light emitting diode 40 takes out light from the n-type layer side. Except for this point, it has the same function as the light emitting diode 30, and the light extraction efficiency can be improved in the same manner as in the case of the light emitting diode 30.

以下、本発明の実施例について説明するが、本発明はこれらの実施例に限定されるものではない。   Examples of the present invention will be described below, but the present invention is not limited to these examples.

図４に示した層構造の発光ダイオードを以下のようにして製作した。成長用基板１としてサファイア（表面は（００１）面の方位面を有する。）基板を用い、サファイア基板１上に、図１の２および３に相当する発光ダイオード構造の窒化物系半導体エピタキシャル結晶を有機金属気相成長法により成長した。すなわち、ＧａＮ低温バッファ層２、高濃度Ｓｉドープｎ+ −ＧａＮ層３１（不純物濃度：２×１０19、層厚：１μｍ）、Ｓｉドープｎ−ＧａＮ層３２（不純物濃度：２×１０18、層厚：３μｍ）、アンドープＧａＮ層３３（層厚：３００ｎｍ）、アンドープＧａＮ層（層厚：１５ｎｍ）とＩｎＧａＮ層（層厚：３ｎｍ）の５回繰り返しからなるＭＱＷ層３４、アンドープＧａＮ層３５（層厚：１８ｎｍ）、Ｍｇドープｎ−ＡｌＧａＮ層３６（Ａｌ５％、不純物濃度＝２×１０16、層厚：２５ｎｍ）、Ｍｇドープｐ−ＧａＮ層３７（層厚：１５０ｎｍ）、Ｓｉドープｎ−ＧａＮ層（不純物濃度：２×１０20、層厚：１ｎｍ）とＳｉドープｎ−ＩｎＧａＮ層（不純物濃度：２×１０20、層厚：１ｎｍ）の５回繰り返しからなるＣＴＬ層３８を成長させた。なお活性層のＩｎＧａＮ層のＩｎ組成は電流注入により発光層から射出される光の波長が４７０ｎｍとなるように調整して決めた。 The light emitting diode having the layer structure shown in FIG. 4 was manufactured as follows. A sapphire substrate (having a (001) plane orientation plane) is used as the growth substrate 1, and a nitride semiconductor epitaxial crystal having a light emitting diode structure corresponding to 2 and 3 in FIG. It was grown by metalorganic vapor phase epitaxy. That is, the GaN low-temperature buffer layer 2, the high-concentration Si-doped n + -GaN layer 31 (impurity concentration: 2 × 10 19 , layer thickness: 1 μm), the Si-doped n-GaN layer 32 (impurity concentration: 2 × 10 18 , layer) (Thickness: 3 μm), undoped GaN layer 33 (layer thickness: 300 nm), MQW layer 34 consisting of five repetitions of undoped GaN layer (layer thickness: 15 nm) and InGaN layer (layer thickness: 3 nm), undoped GaN layer 35 (layer) (Thickness: 18 nm), Mg-doped n-AlGaN layer 36 (Al 5%, impurity concentration = 2 × 10 16 , layer thickness: 25 nm), Mg-doped p-GaN layer 37 (layer thickness: 150 nm), Si-doped n-GaN layer A CTL layer 38 consisting of five repetitions of (impurity concentration: 2 × 10 20 , layer thickness: 1 nm) and a Si-doped n-InGaN layer (impurity concentration: 2 × 10 20 , layer thickness: 1 nm) is grown. I let you. The In composition of the InGaN layer of the active layer was determined by adjusting the wavelength of light emitted from the light emitting layer by current injection to be 470 nm.

次に、透明導電性のホール注入用オーミック電極層４として、膜厚５９ｎｍのＩＴＯ膜を電子ビーム蒸着法により全面に形成した。   Next, as a transparent conductive hole injection ohmic electrode layer 4, an ITO film having a film thickness of 59 nm was formed on the entire surface by an electron beam evaporation method.

このホール注入用オーミック電極層４の上に、引き続いて、次の工程で接着層／反射層２２１となるＴｉ／Ａｌ／Ａｕ積層膜を、５０／２００／５００ｎｍの厚さとなるように蒸着法により全面に形成した。   On the ohmic electrode layer 4 for hole injection, subsequently, a Ti / Al / Au laminated film that becomes an adhesive layer / reflective layer 221 in the next step is deposited by vapor deposition so as to have a thickness of 50/200/500 nm. Formed on the entire surface.

導電性基板２１として低抵抗Ｓｉ（１００）基板を用い、この両面にＳｉ基板に対するオーミック性電極であるＡｌと、後の工程で接着層として用いるＡｕの積層膜（図示しない）を２００／５００ｎｍ形成した後３５０℃で３０分間熱処理したものを準備し、先のＩＴＯ４およびＴｉ／Ａｌ／Ａｕ積層膜２２１を形成した窒化物半導体エピタキシャル結晶と、基板貼り合わせ装置を用いて貼り合わせた。   A low resistance Si (100) substrate is used as the conductive substrate 21, and a laminated film (not shown) of Al, which is an ohmic electrode for the Si substrate, and Au, which is used as an adhesive layer in a later step, is formed on both sides at 200/500 nm. After that, heat-treated at 350 ° C. for 30 minutes was prepared, and bonded to the nitride semiconductor epitaxial crystal on which the ITO 4 and Ti / Al / Au laminated film 221 was formed using a substrate bonding apparatus.

次に貼り合わせた基板から、研磨装置とラッピング装置によりサファイアを削りサファイア厚さ２０μｍまでした。この後、ＩＣＰエッチング装置を用いて、更にサファイアを削り完全に除去し、さらに低温バッファ層２も除去した。こうしてＳｉ基板上にＬＥＤ構造の窒化物半導体が形成され、最表面がＳｉドープｎ型高濃度ＧａＮ３１である構造体が得られた。   Next, sapphire was shaved from the bonded substrates by a polishing apparatus and a lapping apparatus to a thickness of 20 μm. Thereafter, using an ICP etching apparatus, sapphire was further shaved and completely removed, and the low-temperature buffer layer 2 was also removed. Thus, a nitride semiconductor having an LED structure was formed on the Si substrate, and a structure having the outermost surface made of Si-doped n-type high-concentration GaN 31 was obtained.

この構造体（ウェハー）を数個に分割し、最表面のＳｉドープｎ型高濃度ＧａＮ層３１にＩＴＯ透明導電膜からなる電子注入用オーミック電極層２２２と種々の透明性薄膜層５を形成した。   This structure (wafer) was divided into several pieces, and an ohmic electrode layer 222 for electron injection made of an ITO transparent conductive film and various transparent thin film layers 5 were formed on the Si-doped n-type high-concentration GaN layer 31 on the outermost surface. .

〔膜厚λ／２のＩＴＯ＋膜厚λ／４の透明性薄膜（空気用）の構成〕
分割片の１つに、最表面であるＳｉドープｎ型高濃度ＧａＮ層上に、膜厚１１８ｎｍのＩＴＯ膜を電子ビーム蒸着法により全面に形成し、フォトリソグラフィによりパターニングを行った後、ＩＴＯ膜の上に（取出し電極部を除いて）厚さ８０ｎｍのＳｉＯ2 膜を形成しＬＥＤウェハを作製した。 [Configuration of ITO with film thickness λ / 2 + Transparent thin film (for air) with film thickness λ / 4]
As one of the divided pieces, an ITO film having a film thickness of 118 nm is formed on the entire surface by the electron beam evaporation method on the Si-doped n-type high-concentration GaN layer that is the outermost surface, patterned by photolithography, and then the ITO film An SiO 2 film having a thickness of 80 nm was formed on the substrate (excluding the extraction electrode portion) to produce an LED wafer.

〔膜厚λ／４のＩＴＯ＋膜厚λ／４の透明性薄膜＋膜厚λ／４の透明性薄膜（空気用）の構成〕
分割片の１つに、膜厚５９ｎｍのＩＴＯ膜を電子ビーム蒸着法により全面に形成し、ＩＴＯ膜の上に（取出し電極部を除いて）厚さ６２ｎｍのＳｎＯ2 膜と、厚さ８０ｎｍのＳｉＯ2 膜をこの順に形成したことを除いては実施例１と同じ方法によりＬＥＤウェハを作製した。 [Structure of ITO of film thickness λ / 4 + transparent thin film of film thickness λ / 4 + transparent thin film of film thickness λ / 4 (for air)]
An ITO film having a thickness of 59 nm is formed on one surface of the divided piece by an electron beam evaporation method, and a 62 nm thick SnO 2 film (excluding the extraction electrode portion) is formed on the ITO film and a thickness of 80 nm. An LED wafer was produced by the same method as in Example 1 except that the SiO 2 film was formed in this order.

〔膜厚λ／４のＩＴＯ＋膜厚λ／４の透明性薄膜＋膜厚λ／４の透明性薄膜（空気用）の構成〕
ＩＴＯ膜の上に（取出し電極部を除いて）厚さ７４ｎｍのＬａＦ3 膜と、厚さ９５ｎｍのＣａＦ2 膜をこの順に形成したことを除いては実施例２と同じ方法によりＬＥＤウェハを作製した。 [Structure of ITO of film thickness λ / 4 + transparent thin film of film thickness λ / 4 + transparent thin film of film thickness λ / 4 (for air)]
An LED wafer is produced by the same method as in Example 2 except that a LaF 3 film having a thickness of 74 nm and a CaF 2 film having a thickness of 95 nm are formed in this order on the ITO film (excluding the extraction electrode portion). did.

〔膜厚λ／４のＩＴＯ＋膜厚λ／２の透明性薄膜＋膜厚λ／４の透明性薄膜（空気用）の構成〕
ＩＴＯ膜の上に（取出し電極部を除いて）厚さ１６０ｎｍのＳｉＯ2 膜と、厚さ９５ｎｍＣａＦ2 膜をこの順に形成したことを除いては実施例２と同じ方法によりＬＥＤウェハを作製した。 [Structure of ITO with film thickness λ / 4 + Transparent thin film with film thickness λ / 2 + Transparent thin film with film thickness λ / 4 (for air)]
An LED wafer was produced in the same manner as in Example 2 except that a 160 nm thick SiO 2 film and a 95 nm CaF 2 film were formed in this order on the ITO film (excluding the extraction electrode portion).

（比較例１）
〔ＩＴＯのみの構成〕
分割片の１つに、膜厚５９ｎｍのＩＴＯ膜を電子ビーム蒸着法により全面に形成し、フォトリソグラフィによりパターニングを行なう工程のみを行ない、透明性薄膜を形成しなかったことを除いては、実施例２と同様にしてＬＥＤウェハを作製した。 (Comparative Example 1)
[Configuration of ITO only]
Implemented except that an ITO film with a thickness of 59 nm was formed on the entire surface by electron beam evaporation on one of the pieces, and only the patterning process was performed by photolithography, and no transparent thin film was formed. An LED wafer was produced in the same manner as in Example 2.

（比較例２）
〔従来ＴｉＡｌ金属系メッシュ電極〕
分割片の１つに、ＩＴＯ透明電極を形成する替わりに、最表面であるＳｉドープｎ型高濃度ＧａＮ層上に、ＴｉＡｌを１０／１００ｎｍ堆積しメッシュ状パターンにした後Ｎ2 中７００℃でアニールにとりオーミック電極を形成したことを除いては、実施例１と同様にしてＬＥＤウェハを作製した。 (Comparative Example 2)
[Conventional TiAl metal mesh electrode]
Instead of forming the ITO transparent electrode on one of the divided pieces, TiAl was deposited on the Si-doped n-type high-concentration GaN layer, which is the outermost surface, to form a mesh pattern, and then at 700 ° C. in N 2. An LED wafer was produced in the same manner as in Example 1 except that an ohmic electrode was formed for annealing.

（参考例１）
上記実施例１〜５および比較例１で得られたＬＥＤの２０ｍＡにおける光出力の平均値の比較例に対する相対値を表１にしめす。表１からわかるように、本発明の透明性薄膜を積層することにより、光出力が２５〜５０％増大した。 (Reference Example 1)
Table 1 shows the relative values of the average value of the light output at 20 mA of the LEDs obtained in Examples 1 to 5 and Comparative Example 1 with respect to the Comparative Example. As can be seen from Table 1, the light output increased by 25 to 50% by laminating the transparent thin film of the present invention.

（表１）
積層透明膜の構成 光出力（相対値＊）
実施例１ ＩＴＯ／ＳｉＯ2 １．４５
実施例２ ＩＴＯ／ＳｎＯ2 ／ＳｉＯ2 １．４８
実施例３ ＩＴＯ／ＬａＦ3 ／ＣａＦ2 １．４３
実施例４ ＩＴＯ／ＳｉＯ2 ／ＣａＦ2 １．４５
比較例１ ＩＴＯのみ １．２６
比較例２ ＴｉＡｌメッシュ電極 １．００
＊比較例２を１．００とした相対値。 (Table 1)
Structure of laminated transparent film
Example 1 ITO / SiO 2 1.45
Example 2 ITO / SnO 2 / SiO 2 1.48
Example 3 ITO / LaF 3 / CaF 2 1.43
Example 4 ITO / SiO 2 / CaF 2 1.45
Comparative Example 1 ITO only 1.26
Comparative Example 2 TiAl mesh electrode 1.00
* Relative value with Comparative Example 2 as 1.00.

〔膜厚λ／２のＩＴＯ＋膜厚λ／４の透明性薄膜（樹脂用）の構成〕
分割片の１つに、最表面であるＳｉドープｎ型高濃度ＧａＮ層上に、厚さ膜厚１１８ｎｍのＩＴＯ膜を電子ビーム蒸着法により全面に形成し、フォトリソグラフィによりパターニングを行った後、ＩＴＯ膜の上に（取出し電極部を除いて）厚さ６２ｎｍのＳｎＯ2 膜を形成した。 [Configuration of ITO with film thickness λ / 2 + Transparent thin film (for resin) with film thickness λ / 4]
After forming an ITO film with a thickness of 118 nm on the entire surface by an electron beam evaporation method on one of the divided pieces on the Si-doped n-type high-concentration GaN layer, which is the outermost surface, and performing patterning by photolithography, A SnO 2 film having a thickness of 62 nm was formed on the ITO film (excluding the extraction electrode portion).

こうして作製したＬＥＤ構造エピタキシャル基板を、スクライブ・ブレークによりチップ分離して、ＬＥＤチップをリードにボンディングした後、樹脂包埋してＬＥＤを作製した。   The LED structure epitaxial substrate thus fabricated was separated into chips by scribe break, the LED chip was bonded to the lead, and then embedded in a resin to produce an LED.

〔膜厚λ／４のＩＴＯ＋膜厚λ／４の透明性薄膜＋膜厚λ／４の透明性薄膜（樹脂用）の構成〕
分割片の１つに、膜厚５９ｎｍのＩＴＯ膜を形成し、ＩＴＯ膜の上に（取出し電極部を除いて）厚さ７４ｎｍのＬａＦ3 膜と厚さ８０ｎｍのＳｉＯ2 膜をこの順に形成したことを除いて実施例５と同様の工程によりＬＥＤを作製した。 [Structure of ITO with film thickness λ / 4 + Transparent thin film with film thickness λ / 4 + Transparent thin film with film thickness λ / 4 (for resin)]
An ITO film having a thickness of 59 nm was formed on one of the divided pieces, and a LaF 3 film having a thickness of 74 nm and an SiO 2 film having a thickness of 80 nm were formed in this order on the ITO film (excluding the extraction electrode portion). Except for this, an LED was fabricated by the same process as in Example 5.

〔膜厚λ／４のＩＴＯ＋膜厚λ／４の透明性薄膜＋膜厚λ／４の透明性薄膜（樹脂用）の構成〕
分割片の１つに、膜厚５９ｎｍのＩＴＯ膜を形成し、ＩＴＯ膜の上に（取出し電極部を除いて）厚さ６２ｎｍのＳｎＯ2 膜と厚さ６７ｎｍのＭｇＯ膜をこの順に形成したことを除いて実施例５と同様の工程によりＬＥＤを作製した。 [Structure of ITO with film thickness λ / 4 + Transparent thin film with film thickness λ / 4 + Transparent thin film with film thickness λ / 4 (for resin)]
An ITO film with a film thickness of 59 nm was formed on one of the divided pieces, and an SnO 2 film with a thickness of 62 nm and an MgO film with a thickness of 67 nm were formed in this order on the ITO film (excluding the extraction electrode portion). An LED was manufactured by the same process as in Example 5 except for.

〔膜厚λ／４のＩＴＯ＋膜厚λ／２の透明性薄膜＋膜厚λ／４の透明性薄膜（樹脂用）の構成〕
分割片の１つに、厚さ膜厚５９ｎｍのＩＴＯ膜を形成し、ＩＴＯ膜の上に（取出し電極部を除いて）厚さ１６１ｎｍのＳｉＯ2 膜と厚さ７４ｎｍのＬａＦ3 膜をこの順に形成したことを除いて実施例５と同様の工程によりＬＥＤを作製した。 [Structure of ITO with film thickness λ / 4 + Transparent thin film with film thickness λ / 2 + Transparent thin film with film thickness λ / 4 (for resin)]
An ITO film with a thickness of 59 nm is formed on one of the divided pieces, and an SiO 2 film with a thickness of 161 nm and a LaF 3 film with a thickness of 74 nm are formed in this order on the ITO film (excluding the extraction electrode portion). An LED was fabricated by the same process as in Example 5 except that it was formed.

比較例３
〔従来ＴｉＡｌ金属系メッシュ電極〕
分割片の１つに、ＩＴＯ電極を形成する替わりに、最表面であるＳｉドープｎ型高濃度ＧａＮ層上に、ＴｉＡｌを１０／１００ｎｍ形成した後Ｎ2 中７００℃にでアニールを行いオーミック電極を形成したことを除いて、実施例６と同様の工程によりＬＥＤを作製した。 Comparative Example 3
[Conventional TiAl metal mesh electrode]
Instead of forming the ITO electrode on one of the divided pieces, an ohmic electrode is formed by forming 10/100 nm of TiAl on the Si-doped n-type high-concentration GaN layer, which is the outermost surface, and then annealing at 700 ° C. in N 2 An LED was fabricated by the same process as in Example 6 except that was formed.

上記実施例６〜１０および比較例２で得られたＬＥＤの２０ｍＡにおける光出力の平均値の比較例２に対する相対値を表２に示す。表２からわかるように、本発明の透明性薄膜を積層することにより、比較例に比べ光出力が４０〜５０％増大した。   Table 2 shows the relative values of the average value of the light output at 20 mA of the LEDs obtained in Examples 6 to 10 and Comparative Example 2 with respect to Comparative Example 2. As can be seen from Table 2, by laminating the transparent thin film of the present invention, the light output increased by 40 to 50% compared to the comparative example.

（表２）
積層透明膜の構成 光出力（相対値＊＊）
実施例５ ＩＴＯ／ＳｎＯ2 １．４７
実施例６ ＩＴＯ／ＬａＦ3 ／ＳｉＯ2 １．４４
実施例７ ＩＴＯ／ＳｎＯ2 ／ＭｇＯ １．４５
実施例８ ＩＴＯ／ＳｉＯ2 ／ＬａＦ3 １．４６
比較例３ ＴｉＡｌメッシュ電極 １．００
＊＊比較例３を１．００とした相対値。 (Table 2)
Structure of laminated transparent film Light output (relative value **)
Example 5 ITO / SnO 2 1.47
Example 6 ITO / LaF 3 / SiO 2 1.44
Example 7 ITO / SnO 2 / MgO 1.45
Example 8 ITO / SiO 2 / LaF 3 1.46
Comparative Example 3 TiAl mesh electrode 1.00
** Relative value with Comparative Example 3 as 1.00.

本発明による発光ダイオードの実施の形態の一例を示す層構造図。The layer structure figure which shows an example of embodiment of the light emitting diode by this invention. 透明性薄膜を２層設けた場合の構成例の要部を示す図。The figure which shows the principal part of the structural example at the time of providing two transparent thin films. 本発明による発光ダイオードの他の実施の形態を示す層構造図。The layer structure figure which shows other embodiment of the light emitting diode by this invention. 本発明による発光ダイオードの別の実施の形態を示す層構造図。The layer structure figure which shows another embodiment of the light emitting diode by this invention.

符号の説明Explanation of symbols

１ サファイア基板
２ ＧａＮ低温バッファ層
３ 窒化物半導体層
４ ホール注入用オーミック電極層
５ 透明薄膜層
６、７ 取り出し電極
１０、２０、３０ 発光ダイオード
２２ 光反射層
３１ ｎ+ −ＧａＮ層
３２ ｎ−ＧａＮ層
３３ ＧａＮ層
３４ ＭＱＷ層
３５ ＧａＮ層
３６ ｎ−Ａｌ0.15Ｇａ0.85Ｎ層
３７ ｐ−ＧａＮ層
３８ ＣＴＬ層
２２１ 接着／反射層
２２２ 電子注入用オーミック電極層 DESCRIPTION OF SYMBOLS 1 Sapphire substrate 2 GaN low-temperature buffer layer 3 Nitride semiconductor layer 4 Ohmic electrode layer for hole injection 5 Transparent thin film layer 6, 7 Extraction electrode 10, 20, 30 Light-emitting diode 22 Light reflection layer 31 n + -GaN layer 32 n-GaN Layer 33 GaN layer 34 MQW layer 35 GaN layer 36 n-Al 0.15 Ga 0.85 N layer 37 p-GaN layer 38 CTL layer 221 adhesion / reflection layer 222 ohmic electrode layer for electron injection

Claims (12)

発光層とオーミック電極とを有し、前記発光層からの光を光取出し面から素子の外部に出射する化合物半導体発光素子であって、前記発光層に関して光取出し面側にあるオーミック電極が透明導電膜からなり、該透明導電膜の面であって発光層側の面と反対側の面に接して前記光の反射を低減する機能を有する反射率低減層が設けられており、該反射率低減層が１つ以上の透明性薄膜を含んで成っていることを特徴とする化合物半導体発光素子。   A compound semiconductor light emitting device having a light emitting layer and an ohmic electrode, and emitting light from the light emitting layer to the outside of the device from the light extraction surface, wherein the ohmic electrode on the light extraction surface side with respect to the light emitting layer is transparent conductive A reflectance reduction layer made of a film and having a function of reducing the reflection of the light is provided in contact with the surface of the transparent conductive film opposite to the surface on the light emitting layer side. A compound semiconductor light-emitting element, wherein the layer comprises one or more transparent thin films. 前記反射率低減層が、２つ以上の透明性薄膜を積層してなる層である請求項１記載の化合物半導体発光素子。   The compound semiconductor light-emitting element according to claim 1, wherein the reflectance reduction layer is a layer formed by laminating two or more transparent thin films. 前記透明導電膜が、その発光層側の面でコンタクト層と接している請求項１または２記載の化合物半導体発光素子。   The compound semiconductor light-emitting element according to claim 1, wherein the transparent conductive film is in contact with the contact layer on the surface on the light-emitting layer side. 前記透明導電膜の光学膜厚が、発光波長のｍ／４倍（ただしｍは正の整数）である請求項１〜３のいずれかに記載の化合物半導体発光素子。   4. The compound semiconductor light-emitting element according to claim 1, wherein an optical film thickness of the transparent conductive film is m / 4 times the emission wavelength (where m is a positive integer). 前記透明導電膜が、酸化スズが固溶した酸化インジウムからなる透明導電膜である請求項１〜４のいずれかに記載の化合物半導体発光素子。   The compound semiconductor light-emitting element according to claim 1, wherein the transparent conductive film is a transparent conductive film made of indium oxide in which tin oxide is dissolved. 前記透明導電膜と前記各々の透明性薄膜とのいずれの膜においても、膜厚ｄと、屈折率ｎと、発光波長λとの間に、式
ｎ×ｄ＝ｍλ／４（ｍは正の整数）
で示される関係が成り立つ請求項１〜５のいずれかに記載の化合物半導体発光素子。 In any of the transparent conductive film and each of the transparent thin films, the formula n × d = mλ / 4 (m is positive) between the film thickness d, the refractive index n, and the emission wavelength λ. integer)
The compound semiconductor light emitting element in any one of Claims 1-5 with which the relationship shown by these is formed. 前記透明導電膜の光学膜厚が発光波長の１／２であり、前記反射率低減層が一つの透明性薄膜からなり、透明性薄膜の光学膜厚が発光波長の１／４であり、屈折率が１．８〜２．０の範囲または１．４〜１．６の範囲である請求項５記載の化合物半導体発光素子。   The optical film thickness of the transparent conductive film is 1/2 of the emission wavelength, the reflectance reduction layer is made of one transparent thin film, the optical film thickness of the transparent thin film is 1/4 of the emission wavelength, 6. The compound semiconductor light emitting device according to claim 5, wherein the ratio is in the range of 1.8 to 2.0 or in the range of 1.4 to 1.6. 前記透明導電膜の光学膜厚が発光波長の１／４であり、前記反射率低減層が二つの透明性薄膜からなり、前記透明導電膜に接する側の透明性薄膜の光学膜厚が発光波長の１／４であり、屈折率が１．４５〜１．６５の範囲であり、前記透明導電膜に接しない側の透明性薄膜の光学膜厚が発光波長の１／４であり、屈折率が１．４〜１．６の範囲である請求項５記載の化合物半導体発光素子。   The optical film thickness of the transparent conductive film is 1/4 of the emission wavelength, the reflectance reduction layer is composed of two transparent thin films, and the optical film thickness of the transparent thin film on the side in contact with the transparent conductive film is the emission wavelength. The refractive index is in the range of 1.45 to 1.65, the optical thickness of the transparent thin film on the side not in contact with the transparent conductive film is 1/4 of the emission wavelength, and the refractive index. The compound semiconductor light emitting element according to claim 5, wherein is in the range of 1.4 to 1.6. 前記透明導電膜の光学膜厚が発光波長の１／４であり、前記反射率低減層が二つの透明性薄膜からなり、前記透明導電膜に接する側の透明性薄膜の光学膜厚が発光波長の１／４であり、屈折率が１．８〜２．０の範囲であり、前記透明導電膜に接しない側の透明性薄膜の光学膜厚が発光波長の１／４であり、屈折率が１．４〜１．６の範囲である請求項５記載の化合物半導体発光素子。   The optical film thickness of the transparent conductive film is 1/4 of the emission wavelength, the reflectance reduction layer is composed of two transparent thin films, and the optical film thickness of the transparent thin film on the side in contact with the transparent conductive film is the emission wavelength. The optical film thickness of the transparent thin film on the side not in contact with the transparent conductive film is 1/4 of the emission wavelength, and the refractive index. The compound semiconductor light emitting element according to claim 5, wherein is in the range of 1.4 to 1.6. 前記透明導電膜の光学膜厚が発光波長の１／４であり、前記反射率低減層が二つの透明性薄膜からなり、前記透明導電膜に接する側の透明性薄膜の光学膜厚が発光波長の１／４であり、屈折率が１．８〜２．０の範囲であり、前記透明導電膜に接しない側の透明性薄膜の光学膜厚が発光波長の１／４であり、屈折率が１．７〜１．９の範囲である請求項５記載の化合物半導体発光素子。   The optical film thickness of the transparent conductive film is 1/4 of the emission wavelength, the reflectance reduction layer is composed of two transparent thin films, and the optical film thickness of the transparent thin film on the side in contact with the transparent conductive film is the emission wavelength. The optical film thickness of the transparent thin film on the side not in contact with the transparent conductive film is 1/4 of the emission wavelength, and the refractive index. The compound semiconductor light emitting device according to claim 5, wherein is in the range of 1.7 to 1.9. 前記透明導電膜の光学膜厚が発光波長の１／４であり、前記反射率低減層が二つの透明性薄膜からなり、前記透明導電膜に接する側の透明性薄膜の光学膜厚が発光波長の１／４であり、屈折率が１．４５〜１．６５の範囲であり、前記透明導電膜に接しない側の透明性薄膜の光学膜厚が発光波長の１／４であり、屈折率が１．１〜１．３の範囲である請求項５記載の化合物半導体発光素子。   The optical film thickness of the transparent conductive film is 1/4 of the emission wavelength, the reflectance reduction layer is composed of two transparent thin films, and the optical film thickness of the transparent thin film on the side in contact with the transparent conductive film is the emission wavelength. The refractive index is in the range of 1.45 to 1.65, the optical thickness of the transparent thin film on the side not in contact with the transparent conductive film is 1/4 of the emission wavelength, and the refractive index. The compound semiconductor light-emitting device according to claim 5, wherein is in the range of 1.1 to 1.3. 前記透明導電膜の光学膜厚が発光波長の１／４または３／４であり、前記反射率低減層が二つの透明性薄膜からなり、前記透明導電膜に接する側の透明性薄膜の光学膜厚が発光波長の１／２であり、前記透明導電膜に接しない側の透明性薄膜の光学膜厚が発光波長の１／４であり、屈折率が１．５〜１．７の範囲または１．２〜１．４の範囲である請求項５記載の化合物半導体発光素子。   The optical film thickness of the transparent conductive film is 1/4 or 3/4 of the emission wavelength, the reflectance reduction layer is made of two transparent thin films, and the optical film of the transparent thin film on the side in contact with the transparent conductive film The thickness is 1/2 of the emission wavelength, the optical film thickness of the transparent thin film on the side not in contact with the transparent conductive film is 1/4 of the emission wavelength, and the refractive index is in the range of 1.5 to 1.7 or 6. The compound semiconductor light emitting device according to claim 5, which is in a range of 1.2 to 1.4.
JP2004080415A 2004-03-19 2004-03-19 Compound semiconductor light-emitting device Pending JP2005268601A (en)

Priority Applications (3)

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