JPH1012921A - Light-emitting semiconductor element - Google Patents
Light-emitting semiconductor elementInfo
- Publication number
- JPH1012921A JPH1012921A JP16187796A JP16187796A JPH1012921A JP H1012921 A JPH1012921 A JP H1012921A JP 16187796 A JP16187796 A JP 16187796A JP 16187796 A JP16187796 A JP 16187796A JP H1012921 A JPH1012921 A JP H1012921A
- Authority
- JP
- Japan
- Prior art keywords
- layer
- light
- type
- conductive layer
- conductive
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- 239000004065 semiconductor Substances 0.000 title claims abstract description 43
- 239000000758 substrate Substances 0.000 claims abstract description 14
- 239000000463 material Substances 0.000 claims description 6
- 229910001020 Au alloy Inorganic materials 0.000 abstract 1
- 229910052594 sapphire Inorganic materials 0.000 abstract 1
- 239000010980 sapphire Substances 0.000 abstract 1
- 238000000605 extraction Methods 0.000 description 10
- 238000002834 transmittance Methods 0.000 description 4
- 239000000956 alloy Substances 0.000 description 2
- 229910045601 alloy Inorganic materials 0.000 description 2
- 238000005253 cladding Methods 0.000 description 2
- 238000009792 diffusion process Methods 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 238000000034 method Methods 0.000 description 2
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 description 2
- 238000007740 vapor deposition Methods 0.000 description 2
- 229910001218 Gallium arsenide Inorganic materials 0.000 description 1
- 229910006404 SnO 2 Inorganic materials 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000005530 etching Methods 0.000 description 1
- 229910052737 gold Inorganic materials 0.000 description 1
- 125000005842 heteroatom Chemical group 0.000 description 1
- AMGQUBHHOARCQH-UHFFFAOYSA-N indium;oxotin Chemical compound [In].[Sn]=O AMGQUBHHOARCQH-UHFFFAOYSA-N 0.000 description 1
- 238000005468 ion implantation Methods 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- 239000007769 metal material Substances 0.000 description 1
- 238000002488 metal-organic chemical vapour deposition Methods 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- SBIBMFFZSBJNJF-UHFFFAOYSA-N selenium;zinc Chemical compound [Se]=[Zn] SBIBMFFZSBJNJF-UHFFFAOYSA-N 0.000 description 1
- 238000001947 vapour-phase growth Methods 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L29/00—Semiconductor devices adapted for rectifying, amplifying, oscillating or switching, or capacitors or resistors with at least one potential-jump barrier or surface barrier, e.g. PN junction depletion layer or carrier concentration layer; Details of semiconductor bodies or of electrodes thereof ; Multistep manufacturing processes therefor
- H01L29/40—Electrodes ; Multistep manufacturing processes therefor
- H01L29/43—Electrodes ; Multistep manufacturing processes therefor characterised by the materials of which they are formed
- H01L29/45—Ohmic electrodes
- H01L29/452—Ohmic electrodes on AIII-BV compounds
Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、発光半導体素子に
関し、特に、発光層からの光の取り出し効率が向上し得
る発光半導体素子に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light emitting semiconductor device, and more particularly, to a light emitting semiconductor device capable of improving light extraction efficiency from a light emitting layer.
【０００２】[0002]
【従来の技術】従来、発光半導体素子は、例えば青色Ｌ
ＥＤ素子を例にとると、図２に示すように、サファイア
（Ａｌ2Ｏ3）等からなる略透明状の基板３１と、この基
板３１上にＭＯＣＶＤ装置を用いた気相成長方法等によ
り（ＧａＮ等からなるバッファ層（図示せず）を介し
て）形成されたＧａＮ等からなるＰ型半導体層３２及び
Ｎ型半導体層３３と、これらＰ型半導体層３２及びＮ型
半導体層３３間に介設されたＩｎＧａＮ等からなる発光
層３４と、Ｐ型半導体層３２上に形成されたＮｉＡｕ等
の合金からなる透光性の第１導電層３５と、この第１導
電層３５上に形成されたＴｉ、Ａｌ等からなる不透光性
の陽極側の電極層３６と、Ｎ型半導体層３３上のうちエ
ッチングにより除去されて露出状態となった部分にＴ
ｉ、Ａｌ等からなる陰極側の電極層３７とを備えたもの
であり、この発光層３４から発せられる光をこの素子の
電極層３６側の面（以下発光面とする）から取り出すも
のである。 第１導電層３５に用いられるＡｕは、第１
導電層の中では青色光や緑色光のような約５００ｎｍ以
下の波長光に対する透過率が非常に良好なものであり、
ＩｎＧａＮ層等からなる発光層３４からの光が透過しや
すい。2. Description of the Related Art Conventionally, a light-emitting semiconductor device has a
Taking an ED element as an example, as shown in FIG. 2, a substantially transparent substrate 31 made of sapphire (Al 2 O 3 ) and the like, and a vapor phase growth method using an MOCVD apparatus on this substrate 31 ( A P-type semiconductor layer 32 and an N-type semiconductor layer 33 made of GaN or the like formed via a buffer layer (not shown) made of GaN or the like, and an intervening layer between the P-type semiconductor layer 32 and the N-type semiconductor layer 33. The light emitting layer 34 made of InGaN or the like, the light transmitting first conductive layer 35 made of an alloy such as NiAu formed on the P-type semiconductor layer 32, and the light emitting layer 34 formed on the first conductive layer 35 are formed. A non-translucent anode-side electrode layer 36 made of Ti, Al, or the like, and a portion of the N-type semiconductor layer 33 which has been removed by etching and exposed to T.
and a cathode-side electrode layer 37 made of i, Al, or the like. Light emitted from the light-emitting layer 34 is extracted from the surface of the element on the electrode layer 36 side (hereinafter referred to as a light-emitting surface). . Au used for the first conductive layer 35 is the first conductive layer 35.
In the conductive layer, the transmittance for light having a wavelength of about 500 nm or less, such as blue light and green light, is very good,
Light from the light emitting layer 34 composed of an InGaN layer or the like is easily transmitted.
【０００３】上記ＩＴＯ層７は、その厚み寸法が１００
０〜２０００オングストローム程度となっている。上記
第１導電層３５は、蒸着等によりＰ型半導体層３２上に
形成され、その後に４００℃程度の温度下でアニールし
合金化され、Ｐ型半導体層３２との接合面での抵抗率を
低く下げられた状態で（できるだけオーミック接合とな
るように）形成されている。第１導電層３５と電極層３
６との接合面は、複数の凹凸部が形成された非常に表面
状態の悪いものとなっている。The above-mentioned ITO layer 7 has a thickness of 100
It is about 0 to 2000 angstroms. The first conductive layer 35 is formed on the P-type semiconductor layer 32 by vapor deposition or the like, and is then annealed and alloyed at a temperature of about 400 ° C. to reduce the resistivity at the joint surface with the P-type semiconductor layer 32. It is formed in a state of being lowered (to obtain an ohmic junction as much as possible). First conductive layer 35 and electrode layer 3
6 has a very poor surface condition in which a plurality of uneven portions are formed.
【０００４】また、第１導電層３５は、その上面側に位
置する電極層３６とのオーミック接合を得るためのもの
でもある。さらに、第１導電層３５は、電極層３６から
の電流を抵抗の高いＰ型半導体層３２に流れる前に表面
方向（図中の左右方向）に分散するように広げ、発光層
３４内を流れる面積を大きくさせることにより、該発光
層３４における発光面積を大きくするために、その厚み
寸法を５０オングストローム程度の厚いものとしてい
る。The first conductive layer 35 is also for obtaining an ohmic junction with the electrode layer 36 located on the upper surface side. Further, the first conductive layer 35 spreads so as to disperse the current from the electrode layer 36 in the surface direction (left-right direction in the drawing) before flowing to the high-resistance P-type semiconductor layer 32, and flows in the light emitting layer 34. In order to increase the light emitting area in the light emitting layer 34 by increasing the area, the thickness thereof is set to be as large as about 50 angstroms.
【０００５】[0005]
【発明が解決しようとする課題】このため、発光層３４
から発せられる光は、その一部が厚み寸法の大きな第１
導電層３５内で吸収されてしまうので、光の取り出し効
率が極めて悪くなる。一方、電極層３６の下方に位置す
る発光層３４では、電極層３６から発光層３４へ流れる
電流量が多く、発生する光の量が最も多いのだが、この
光は複数の凹凸部が形成され表面状態の悪い上記電極層
３６の接合面で散乱したり吸収されてしまうので、光の
取り出し効率が極めて悪くなる。Therefore, the light emitting layer 34
The light emitted from the first part has a large thickness dimension.
Since the light is absorbed in the conductive layer 35, the light extraction efficiency is extremely low. On the other hand, in the light-emitting layer 34 located below the electrode layer 36, the amount of current flowing from the electrode layer 36 to the light-emitting layer 34 is large and the amount of generated light is the largest, but this light has a plurality of uneven portions. Since the light is scattered or absorbed at the bonding surface of the electrode layer 36 having a poor surface condition, the light extraction efficiency is extremely low.
【０００６】このため、この半導体素子を用いて所定の
発光量を得るためには、これに付加する電流量を大きく
する必要があるので、消費電力が非常に大きくなってし
まうといった問題がある。特に、半導体発光素子は、近
年例えば携帯電話等の電源を内蔵した電子機器に用いら
れる場合が多く、電子機器を極力長時間継続して使用す
るために、その消費電力（内蔵電源に対する）が小さい
状態で大きな輝度を得られるものが要求されている。[0006] Therefore, in order to obtain a predetermined light emission amount using this semiconductor element, it is necessary to increase the amount of current added thereto, resulting in a problem that the power consumption becomes extremely large. In particular, in recent years, semiconductor light-emitting elements are often used in electronic devices having a built-in power supply, such as mobile phones, for example, and their power consumption (relative to the built-in power supply) is small because the electronic devices are used for as long as possible. What can obtain a large luminance in a state is demanded.
【０００７】本発明は、このような事情に鑑みてなされ
たものであって、少ない消費電力で大きな輝度を得るこ
とが可能な、光の取り出し効率が良好となる発光半導体
素子を提供することを課題とする。The present invention has been made in view of such circumstances, and an object of the present invention is to provide a light-emitting semiconductor device which can obtain a large luminance with low power consumption and which has good light extraction efficiency. Make it an issue.
【０００８】[0008]
【課題を解決するための手段】上記課題を解決するた
め、本発明は、基板と、この基板上にＰ型とＮ型の半導
体層に挟まれるように形成された発光層と、前記半導体
層上に形成された第１導電層と、この第１導電層上に形
成された略透明の第２導電層と、この第２導電層上に形
成された電極層と、を備えた発光半導体素子を提供する
ものである。In order to solve the above-mentioned problems, the present invention provides a substrate, a light emitting layer formed on the substrate so as to be sandwiched between P-type and N-type semiconductor layers, A light emitting semiconductor device comprising: a first conductive layer formed thereon; a substantially transparent second conductive layer formed on the first conductive layer; and an electrode layer formed on the second conductive layer. Is provided.
【０００９】[0009]
【発明の実施の形態】以下、本発明の実施の形態を、発
光半導体素子として青色ＬＥＤ素子を例にとり、図を参
照しつつ説明するが、本発明はこれらに限定されるもの
でない。図１は、青色ＬＥＤ素子の断面を示す概略図で
ある。この青色ＬＥＤ素子は、サファイア（Ａｌ2Ｏ3）
からなる基板１と、この基板１上にＧａＮからなるバッ
ファ層２を介して形成されたＰ型ＧａＮ層（Ｐ型半導体
層）３及びＮ型ＧａＮ層４（Ｎ型半導体層）と、これら
Ｐ型ＧａＮ層３及びＮ型ＧａＮ層４の間に形成されたＩ
ｎＧａＮ層（発光層）５と、Ｐ型ＧａＮ層３上に形成さ
れた透光性のＮｉとＡｕとの合金からなるＮｉＡｕ層
（第１導電層）６と、このＮｉＡｕ層６上に形成された
ほぼ透明のＩＴＯ（Indium-Tin-Oxide）層（第２導電
層）７と、このＩＴＯ層７上の略中央部分に形成された
Ａｌからなる平面視略円形状の陽極電極層（電極層）８
（平面視の図示はしない）とを備えたものであり、Ｉｎ
ＧａＮ層５及びその周辺のＰ型ＧａＮ層３及びＮ型Ｇａ
Ｎ層４において青色光が発せられる。DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the drawings, taking a blue LED element as an example of a light emitting semiconductor element, but the present invention is not limited to these. FIG. 1 is a schematic diagram showing a cross section of a blue LED element. This blue LED element is made of sapphire (Al 2 O 3 )
A P-type GaN layer (P-type semiconductor layer) 3 and an N-type GaN layer 4 (N-type semiconductor layer) formed on the substrate 1 via a buffer layer 2 of GaN, Formed between the n-type GaN layer 3 and the n-type GaN layer 4
An nGaN layer (light emitting layer) 5, a NiAu layer (first conductive layer) 6 formed of an alloy of translucent Ni and Au formed on the P-type GaN layer 3, and formed on the NiAu layer 6. A substantially transparent ITO (Indium-Tin-Oxide) layer (second conductive layer) 7 and a substantially circular anode electrode layer (electrode layer) made of Al formed at a substantially central portion on the ITO layer 7. ) 8
(Not shown in a plan view).
GaN layer 5 and its surrounding P-type GaN layer 3 and N-type Ga
Blue light is emitted in the N layer 4.
【００１０】Ｎ型ＧａＮ層４は、基板１上の端部におい
て露出した状態となっており、この露出したＮ型ＧａＮ
層４上にはＴｉとＡｌとの積層構造からなる陰極電極層
９が形成されている。上記ＮｉＡｕ層６には、その略中
央部分に貫通穴６ａが穿設されており、ＩＴＯ層７がこ
の貫通穴６ａ内に入り込むように形成されている。この
貫通穴６ａは、陽極電極層８とほぼ同一形状となってい
る。尚、ＮｉＡｕ層６の厚み寸法は、１５オングストロ
ーム程度である。The N-type GaN layer 4 is exposed at an end on the substrate 1, and the exposed N-type GaN
On the layer 4, a cathode electrode layer 9 having a laminated structure of Ti and Al is formed. The NiAu layer 6 has a through hole 6a formed at a substantially central portion thereof, and the ITO layer 7 is formed so as to enter the through hole 6a. This through hole 6a has substantially the same shape as the anode electrode layer 8. The thickness of the NiAu layer 6 is about 15 Å.
【００１１】このような構造を有する青色ＬＥＤ素子で
は、陽極電極層８からの電流がＩＴＯ層７内で十分に面
方向に広がるので、ＩＴＯ層７下の光を吸収するＮｉＡ
ｕ層６を薄くすることが可能となり、ＩｎＧａＮ層５か
らの光がＮｉＡｕ層６内で吸収される率を低くできるた
め、光の取り出し効率が非常に良好となる。また、陽極
電極層８下に位置するＮｉＡｕ層６には貫通穴６ａが存
在し、この位置ではＰ型ＧａＮ層３とＩＴＯ層７とが接
触した状態となる。従って、Ｐ型ＧａＮ層３とＩＴＯ層
７との接合面におけるｐｎ接合が、陽極電極層８からＩ
ｎＧａＮ層５に向かう電流の流れ方向に対して逆方向の
接合となり、この接合面では電流が流れなくなるので、
この流れなくなる電流の分だけその他の部分（陽極電極
層８下以外の部分）に電流が集中して流れるため、Ｉｎ
ＧａＮ層５からの光は、不透光性の陽極電極層８に反射
して拡散してしまう率が減少し、光の取り出し効率がよ
り良好となる。In the blue LED device having such a structure, since the current from the anode electrode layer 8 spreads sufficiently in the plane direction in the ITO layer 7, NiA absorbing the light under the ITO layer 7 can be used.
Since the thickness of the u layer 6 can be reduced and the rate at which light from the InGaN layer 5 is absorbed in the NiAu layer 6 can be reduced, the light extraction efficiency becomes very good. The NiAu layer 6 located under the anode electrode layer 8 has a through hole 6a, and the P-type GaN layer 3 and the ITO layer 7 are in a contact state at this position. Therefore, the pn junction at the junction between the P-type GaN layer 3 and the ITO layer 7 is
The junction is in the opposite direction to the direction of current flow toward the nGaN layer 5, and no current flows at this junction surface.
Since the current intensively flows to other portions (the portions other than under the anode electrode layer 8) by the amount of the current that stops flowing, In
The rate at which the light from the GaN layer 5 is reflected and diffused by the light-impermeable anode electrode layer 8 is reduced, and the light extraction efficiency is further improved.
【００１２】さらに、本実施例の青色ＬＥＤ素子では、
陽極電極層８をＩＴＯ層７上に接合しているので、陽極
電極層８の接合面は、従来のようにＮｉＡｕ層６と陽極
電極層８とを合金化したときにＮｉＡｕ層６下面の表面
状態が悪くなってしまうということもほぼなく、鏡面状
態を維持できるため、たとえＩｎＧａＮ層５からの光が
陽極電極層８に反射しても拡散する率が減少され、反射
した後に上方に光が発せられやすく、その分だけ光の取
り出し効率が良好となる。Further, in the blue LED element of this embodiment,
Since the anode electrode layer 8 is bonded on the ITO layer 7, the bonding surface of the anode electrode layer 8 is formed on the surface of the lower surface of the NiAu layer 6 when the NiAu layer 6 and the anode electrode layer 8 are alloyed in the conventional manner. Since the state is hardly deteriorated and the mirror state can be maintained, even if the light from the InGaN layer 5 is reflected on the anode electrode layer 8, the diffusion rate is reduced, and the light is reflected upward after the reflection. The light is easily emitted, and the light extraction efficiency is improved accordingly.
【００１３】本実施例における第１導電層としてのＮｉ
Ａｕ層６の厚み寸法は、１５オングストローム程度とし
ているが、これに限定されるものでなく、第１導電層と
しての導電状態を得られ且つ従来よりも薄い５〜４０オ
ングストローム程度の範囲であればよく、１０〜２０オ
ングストローム程度であれば光の透過率及び電流の面方
向への広がりを両方満足させやすいのでより好ましい。In this embodiment, Ni as the first conductive layer
The thickness of the Au layer 6 is about 15 angstroms, but is not limited to this. If the conductive state as the first conductive layer can be obtained and the thickness is about 5 to 40 angstroms which is thinner than the conventional one. It is more preferable that the thickness is about 10 to 20 Å because it is easy to satisfy both the light transmittance and the spread of the current in the plane direction.
【００１４】また、本実施例におけるＩＴＯ層７の厚み
寸法は、１０００〜２０００オングストローム程度であ
るが、形成条件により抵抗率、透過率が共に下がる膜厚
にすれば良く、このＩＴＯ層７は好ましくは比抵抗５Ω
ｃｍ以下であって発光波長に対する透過率８５％以上の
ものがよい。さらに、本実施例では、第２導電層の材料
としてＩＴＯを用いているが、これに限定されるもので
なく、Ｉｎ2Ｏ3系、ＳｎＯ2系やＺｎＯ2系のほぼ透明の
導電膜を用いてもよい。The thickness of the ITO layer 7 in this embodiment is about 1,000 to 2,000 angstroms. However, the thickness may be reduced so that both the resistivity and the transmittance are reduced depending on the forming conditions. Is the specific resistance 5Ω
cm or less and a transmittance of 85% or more with respect to the emission wavelength is preferred. Furthermore, in the present embodiment, ITO is used as the material of the second conductive layer, but the present invention is not limited to this, and an almost transparent conductive film of In 2 O 3 , SnO 2, or ZnO 2 is used. May be used.
【００１５】また、本実施例におけるＮｉＡｕ層６の貫
通穴６ａを、陽極側電極層の形状とほぼ同一形状として
いるが、これに限定されるものでなく、発光させたい部
分のみに第１導電層を残すようにすればよい。さらに、
本実施例では、陽極側電極層の材料としてＡｌを用いて
いるが、これに限定するものでなく、光に対する反射率
の高いＡｇ等の金属材料を用いてもよい。また、陰極側
電極層の材料としてＴｉとＡｌの積層を用いているが、
これに限定するものでなく、Ａｌ等の金属を用いてもよ
い。The through-hole 6a of the NiAu layer 6 in this embodiment has substantially the same shape as the shape of the anode-side electrode layer, but is not limited to this. What is necessary is just to leave a layer. further,
In this embodiment, Al is used as the material of the anode-side electrode layer. However, the present invention is not limited to this, and a metal material such as Ag having a high light reflectance may be used. In addition, a laminate of Ti and Al is used as a material of the cathode side electrode layer,
The present invention is not limited to this, and a metal such as Al may be used.
【００１６】加えて、本実施例では、Ｐ型ＧａＮ層３上
に第１導電層としてＮｉＡｕ層６を形成しているが、こ
れに限定するものでなく、Ａｕ層、Ｃｕ層またはこれら
の合金層であってもよい。また、この第１導電層の形成
は、蒸着以外にイオン注入方法等により高密度にイオン
を注入して表面を金属化させてもよい。また、本実施例
では、基板上にバッファ層を介してＮ型半導体層、発光
層及びＰ型半導体層を下から順に形成しているが、これ
に限定されるものでなく、Ｎ型半導体層とＰ型半導体層
とが逆となった構造のものでもよく、この場合にはＰ型
の第２導電層を形成すればよい。In addition, in this embodiment, the NiAu layer 6 is formed as the first conductive layer on the P-type GaN layer 3. However, the present invention is not limited to this. It may be a layer. In forming the first conductive layer, ions may be implanted at a high density by an ion implantation method or the like in addition to vapor deposition to metallize the surface. Further, in this embodiment, the N-type semiconductor layer, the light-emitting layer, and the P-type semiconductor layer are sequentially formed from below on the substrate via the buffer layer. However, the present invention is not limited to this. In this case, a P-type second conductive layer may be formed.
【００１７】さらに、本実施例では、発光半導体素子と
してＧａＮ系ＬＥＤ素子を例にとり説明しているが、こ
れに限定するものでなく、ＧａＡｓ系材料等の基板を用
いた様々なＬＥＤ素子にも適用可能であり、例えば、Ｇ
ａＡｓ基板上にＺｎＳｅからなるバッファ層を介してＭ
ｇＺｎＳＳｅからなるＰ型及びＮ型の半導体層を形成
し、これら半導体層間にＺｎＳＳｅからなる発光層を形
成し、さらに、Ｐ型層上に上記実施例で記載したような
第１導電層、透明電極層及び金属電極層を形成したＺｎ
Ｓｅ系ＬＥＤ素子にも適用可能である。尚、本発明は、
Ｐ型もしくはＮ型半導体層上の第１導電層及び第２導電
層の構造に特徴を有するものであり、Ｎ型もしくはＰ型
半導体層下の構造組成及び成分比については、これを限
定するものでない。Further, in this embodiment, a GaN-based LED device is described as an example of a light-emitting semiconductor device, but the present invention is not limited to this, and various LED devices using a substrate such as a GaAs-based material can be used. Applicable, for example, G
M is formed on the aAs substrate via a buffer layer made of ZnSe.
g P-type and N-type semiconductor layers made of ZnSSe are formed, a light emitting layer made of ZnSSe is formed between these semiconductor layers, and a first conductive layer and a transparent electrode as described in the above embodiment are further formed on the P-type layer. Layer and metal electrode layer formed Zn
It is also applicable to Se-based LED elements. In addition, the present invention
The structure is characterized by the structure of the first conductive layer and the second conductive layer on the P-type or N-type semiconductor layer, and the structure composition and component ratio under the N-type or P-type semiconductor layer are limited. Not.
【００１８】尚、本実施例の発光半導体素子は、発光層
をほぼ同一の材質であるＰ型半導体層及びＮ型半導体層
で挟んだいわゆるダブルヘテロ構造であるが、これに限
定されるものでなく、本発明はＰＮ接合のみであるホモ
接合型のＬＥＤ素子にも適用可能である。The light-emitting semiconductor device of this embodiment has a so-called double hetero structure in which a light-emitting layer is sandwiched between a P-type semiconductor layer and an N-type semiconductor layer, which are substantially the same material. However, the present invention is not limited to this. Instead, the present invention is also applicable to a homojunction type LED element having only a PN junction.
【００１９】[0019]
【発明の効果】以上の説明からも明らかなように、本発
明によれば、次のような効果を奏する。 （１）電極層からの電流が第２導電層内で十分に面方向
に広がるので、第２導電層下の抵抗の高い第１導電層を
薄くすることが可能となり、発光層からの光が第１導電
層内で吸収される率を低くできるため、光の取り出し効
率が非常に良好となる。 （２）電極層下に位置する第１導電層には貫通穴が存在
し、この位置ではＰ型ＧａＮ系クラッド層と第２導電層
とが接触した状態となる。従って、Ｐ型ＧａＮクラッド
層と第２導電層との接合面におけるｐｎ接合が、電極層
からＧａＮ系発光層に向かう電流の流れ方向に対して逆
方向の接合となり、この接合面では電流が流れなくなる
ので、この流れなくなる電流の分だけその他の部分（電
極層下以外の部分）に電流が集中して流れるため、Ｇａ
Ｎ系発光層からの光は、不透光性の電極層に反射して拡
散してしまう率が減少し、光の取り出し効率がより良好
となる。 （３）電極層を第２導電層上に接合しているので、電極
層の接合面は、従来のように第１導電層と電極層とを合
金化したときに第１導電層下面の表面状態が悪くなって
しまうということもほぼなく、鏡面状態を維持できるた
め、たとえＧａＮ系発光層からの光が電極層に反射して
も拡散する率が減少され、反射した後に上方に光が発せ
られやすく、その分だけ光の取り出し効率が良好とな
る。As is clear from the above description, the present invention has the following effects. (1) Since the current from the electrode layer spreads sufficiently in the plane direction in the second conductive layer, the first conductive layer having a high resistance under the second conductive layer can be thinned, and light from the light emitting layer can be reduced. Since the rate of absorption in the first conductive layer can be reduced, the light extraction efficiency becomes very good. (2) There is a through hole in the first conductive layer located below the electrode layer, and at this position, the P-type GaN-based cladding layer and the second conductive layer are in contact with each other. Therefore, the pn junction at the junction between the P-type GaN cladding layer and the second conductive layer is a junction in the direction opposite to the direction of current flow from the electrode layer to the GaN-based light-emitting layer. Since the current intensively flows in other portions (the portions other than below the electrode layer) by the amount of the current that no longer flows, Ga
The rate at which light from the N-based light emitting layer is reflected and diffused by the light-impermeable electrode layer is reduced, and the light extraction efficiency is further improved. (3) Since the electrode layer is bonded to the second conductive layer, the bonding surface of the electrode layer becomes the surface of the lower surface of the first conductive layer when the first conductive layer and the electrode layer are alloyed as in the related art. Since the mirror condition can be maintained almost without deterioration of the state, even if the light from the GaN-based light emitting layer is reflected on the electrode layer, the diffusion rate is reduced, and light is emitted upward after reflection. And the light extraction efficiency is improved accordingly.
【図１】 本実施例の青色ＬＥＤ素子を示す要部断面
図である。FIG. 1 is a sectional view of a main part showing a blue LED element of the present embodiment.
【図２】 従来の青色ＬＥＤ素子を示す要部断面図で
ある。FIG. 2 is a sectional view of a main part showing a conventional blue LED element.
１ 基板 ２ バッファ層 ３ Ｐ型ＧａＮ層 ４ Ｎ型ＧａＮ層 ５ ＩｎＧａＮ層 ６ ＮｉＡｕ層 ７ ＩＴＯ層 ８ 陽極電極層 ９ 陰極電極層 DESCRIPTION OF SYMBOLS 1 Substrate 2 Buffer layer 3 P-type GaN layer 4 N-type GaN layer 5 InGaN layer 6 NiAu layer 7 ITO layer 8 Anode electrode layer 9 Cathode electrode layer
Claims (4)
体層に挟まれるように形成された発光層と、前記半導体
層上に形成された第１導電層と、この第１導電層上に形
成された略透明の第２導電層と、この第２導電層上に形
成された電極層と、を備えた発光半導体素子。1. A substrate, a light emitting layer formed on the substrate so as to be sandwiched between P-type and N-type semiconductor layers, a first conductive layer formed on the semiconductor layer, and a first conductive layer formed on the semiconductor layer. A light emitting semiconductor device comprising: a substantially transparent second conductive layer formed on a layer; and an electrode layer formed on the second conductive layer.
に位置する部位に貫通穴が設けられていることを特徴と
する請求項１に記載の発光半導体素子。2. The light emitting semiconductor device according to claim 1, wherein a through hole is provided in the first conductive layer at a position below the electrode layer.
至４０オングストロームであることを特徴とする請求項
１もしくは請求項２に記載の発光半導体素子。3. The light emitting semiconductor device according to claim 1, wherein the first conductive layer has a thickness of 5 to 40 angstroms.
からなる請求項１〜請求項３に記載の発光半導体素子。4. The light emitting semiconductor device according to claim 1, wherein said semiconductor layer and said light emitting layer are made of a GaN-based material.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP16187796A JP3746569B2 (en) | 1996-06-21 | 1996-06-21 | Light emitting semiconductor device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP16187796A JP3746569B2 (en) | 1996-06-21 | 1996-06-21 | Light emitting semiconductor device |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH1012921A true JPH1012921A (en) | 1998-01-16 |
| JP3746569B2 JP3746569B2 (en) | 2006-02-15 |
Family
ID=15743688
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP16187796A Expired - Fee Related JP3746569B2 (en) | 1996-06-21 | 1996-06-21 | Light emitting semiconductor device |
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| Country | Link |
|---|---|
| JP (1) | JP3746569B2 (en) |
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| JP2001044495A (en) * | 1999-07-29 | 2001-02-16 | Showa Denko Kk | AlGaInP LIGHT EMITTING DIODE |
| US6287947B1 (en) | 1999-06-08 | 2001-09-11 | Lumileds Lighting, U.S. Llc | Method of forming transparent contacts to a p-type GaN layer |
| EP1320894A1 (en) * | 2000-07-26 | 2003-06-25 | American Xtal Technology, Inc. | IMPROVED WINDOW FOR GaN LED |
| US6818467B2 (en) | 2002-03-25 | 2004-11-16 | Pohang University Of Science And Technology Foundation | P-type ohmic electrode in gallium nitride based optical device and fabrication method thereof |
| US6872649B2 (en) | 1999-04-15 | 2005-03-29 | Sumitomo Electric Industries, Ltd. | Method of manufacturing transparent conductor film and compound semiconductor light-emitting device with the film |
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