JP2004235505A - Ohmic electrode structure for light emitting element and semiconductor element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light emitting element in which a good ohmic contact is ensured between AlGaInP or InGaAlN and an Ag based reflective metal layer and light take-out efficiency can be enhanced furthermore for lights from blue color to green color. <P>SOLUTION: The light emitting element 100 has such a structure as an emission layer part 24 is pasted through a transparent conductive layer 30 to the major surface of a transparent conductive substrate, i.e. a GaP substrate 7 of n-type GaP single crystal. The major rear surface of the GaP substrate 7 is covered with an Ag based reflective metal layer 15, e.g. an Ag layer. Between the GaP substrate 7 and the Ag based reflective metal layer 15, an AgGeNi contact layer 32 alloying AgGeNi contact metal with the surface part of the GaP substrate 7 is formed on the major surface of the Ag based reflective metal layer 15 while being distributed. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a light emitting device and an ohmic electrode structure for a semiconductor device.
[0002]
[Prior art]
[Patent Document 1]
Japanese Patent Application Laid-Open No. 7-66455 [Patent Document 2]
JP-A-11-191641
Materials and device structures used for light-emitting devices such as light-emitting diodes and semiconductor lasers have been developed over many years, and the photoelectric conversion efficiency inside the devices is gradually approaching the theoretical limit. Therefore, when an element with higher luminance is to be obtained, the light extraction efficiency from the element is extremely important. For example, in a light emitting device having a light emitting layer portion formed of AlGaInP mixed crystal, a thin AlGaInP (or GaInP) active layer is sandwiched between an n-type AlGaInP cladding layer and a p-type AlGaInP cladding layer having a larger band gap. By adopting the double hetero structure sandwiched therebetween, an element having an emission wavelength in a green to red region and high luminance can be realized. Such an AlGaInP double hetero structure can be formed by epitaxially growing each layer made of an AlGaInP mixed crystal on a GaAs single crystal substrate, utilizing the fact that the AlGaInP mixed crystal lattice-matches with GaAs. When this is used as a light emitting element, a GaAs single crystal substrate is often used as it is as an element substrate. However, the AlGaInP mixed crystal constituting the light emitting layer has a band gap larger than that of GaAs, so that the emitted light is absorbed by the GaAs substrate and it is difficult to obtain sufficient light extraction efficiency. In order to solve this problem, a method has been proposed in which a reflective layer made of a semiconductor multilayer film is inserted between a substrate and a light emitting element (for example, Patent Document 1). Is used, only light incident at a limited angle is reflected, and a significant improvement in light extraction efficiency cannot be expected in principle.
[0004]
Therefore, a technique is known in which a GaAs substrate for growth is peeled off, and a conductive substrate for reinforcement is bonded to a peeled surface via an Au layer also serving as a reflective layer. This Au layer has the advantage that the reflectance is high and the dependency of the reflectance on the incident angle is small. However, when an Au layer is used as the reflective layer, a sufficient reflection effect cannot be obtained depending on the wavelength of the light emitting layer portion, and the light extraction efficiency does not improve remarkably as expected. The reason for this is that Au has strong absorption in the visible light region having a wavelength of 670 nm or less, and when the peak emission wavelength of the light emitting layer portion is at 670 nm or less, the reflectance is significantly reduced. As a result, the total light emission intensity is easily reduced, and the spectrum of the extracted light is different from the original light emission spectrum due to absorption. A proposal to use Ag as the reflective metal layer is disclosed in Patent Document 2.
[0005]
[Problems to be solved by the invention]
However, in the light-emitting device described in Patent Document 2, a nitride-based III-V compound semiconductor including a light-emitting layer portion is used as a compound semiconductor layer on which an Ag-based reflective metal layer is formed. In order to make ohmic contact with the reflective metal layer, a single metal layer for forming an ohmic contact made of any of Ni, Co, Mg, and Sb is formed on the compound semiconductor, and the above is covered with an Ag-based reflective metal layer. are doing. However, any single metal of Ni, Co, Mg, and Sb has a problem that the reflectivity for blue to green light is not always good.
[0006]
An object of the present invention is to provide a light-emitting element capable of forming a good ohmic contact between AlGaInP or InGaAlN and an Ag-based reflective metal layer and further improving the light extraction efficiency for blue to green light, and an Ag-based light-emitting element. An object of the present invention is to provide an ohmic electrode structure for a semiconductor element including an electrode layer made of a metal and capable of forming good ohmic contact at low cost in a semiconductor device such as a light emitting element.
[0007]
[Means for Solving the Problems and Functions / Effects]
In order to solve the above problems, the light emitting element of the present invention has a light extraction surface formed on the main surface side of a light emitting layer portion having a peak wavelength of 450 nm or more and 580 nm or less made of a first compound semiconductor, Ag containing Ag as a main component, on the main back surface of the portion or on the main back surface of the auxiliary compound semiconductor layer made of the second compound semiconductor transparent to the luminous flux electrically coupled to the main back surface of the light emitting layer portion. An Ag-based contact layer composed of an alloyed layer of a system-based contact metal and a compound semiconductor that forms the main back surface is formed, and further covers the Ag-based contact layer and reflects light from the light emitting layer to the light extraction surface side. And an Ag-based reflective metal layer made of a metal containing Ag as a main component. In this specification, the “main component” refers to a component having the highest mass content.
[0008]
According to the structure of the light emitting device of the present invention, the Ag-based contact metal is formed on the main back surface of the compound semiconductor layer on which the Ag-based reflective metal layer is to be disposed, and the Ag-based compound semiconductor layer and the Ag-based contact metal are alloyed. An Ag-based reflective metal layer is formed so as to cover the contact layer. When the dopant element for forming the ohmic contact is alloyed with the compound semiconductor layer together with Ag, the ohmic contact with the Ag-based reflective metal layer is dramatically improved. In addition, since the contact layer is formed as an alloy layer having a high Ag content, the peak wavelength is 450 nm or more and 580 nm or less, that is, light extraction efficiency for blue to green light is reduced by using a single metal such as Ni, Co, Mg, and Sb. This can be further increased as compared with the case where the contact layer is used.
[0009]
The Ag-based reflective metal layer is overwhelmingly cheaper than the reflective metal layer made of Au-based metal, and has a better reflectivity than Au-based metal over almost the entire visible light wavelength range (350 nm to 700 nm). And the wavelength dependence of the reflectance is small. As a result, high light extraction efficiency can be realized regardless of the emission wavelength of the element. Also, compared to a metal such as Al, a decrease in reflectance due to the formation of an oxide film and the like is less likely to occur even for blue to green light emission. FIG. 3 shows the reflectivity of various mirror-polished metal surfaces. The plot point “■” indicates the reflectivity of Ag, the plot point “△” indicates the reflectivity of Au, and the plot point “◆” indicates the reflectivity. It is a reflectance (comparative example) of Al. The plot point “x” is an AgPdCu alloy. The reflectance of Ag is particularly good when the reflectance of Ag is 350 nm or more and 700 nm or less (and in the infrared region on the longer wavelength side), particularly, 380 nm or more and 700 nm or less. Naturally, as in the present invention, good reflectance can be obtained even in a blue to green emission wavelength region having a peak wavelength of 450 nm or more and 580 nm or less.
[0010]
On the other hand, Au is a colored metal, and as is clear from the reflectance shown in FIG. 3, it has strong absorption in the visible light region having a wavelength of 670 nm or less (especially 650 nm or less: absorption is even greater at 600 nm or less), and the light-emitting layer When the peak emission wavelength of the portion exists at 670 nm or less, the reflectance is significantly reduced. As a result, for light emission having a peak wavelength of 450 nm or more and 580 nm or less, such as blue or green, the emission intensity naturally tends to decrease, and the spectrum of the extracted light differs from the original emission spectrum due to absorption. And a change in emission color tone is likely to occur. However, Ag employed in the present invention has a very good reflectance even in the visible light region having a wavelength of 670 nm or less. That is, by employing the Ag-based reflective metal layer, it is possible to realize a much higher light extraction efficiency for blue and green light emission than Au.
[0011]
On the other hand, as shown in FIG. 3, the absorption peak does not occur even in the reflectance of Al, but the reflectance in the visible light region has a slightly lower value (for example, 85 to 92%) because the reflectance is reduced due to the formation of the oxide film. ). However, Ag employed in the present invention does not easily form an oxide film, so that a higher reflectance than Al can be secured in the visible light region. Specifically, it can be seen that in the emission wavelength range from blue to green having a wavelength of 400 nm or more, particularly 450 nm or more and 580 nm or less, the reflectance is better than that of Al. Emitting layer portion having a peak emission wavelength as described above, for example, _{(Al x Ga 1-x)} y In 1-y P ( However, 0 ≦ x ≦ 1,0 ≦ y ≦ 1) or _In x _Ga y Al _{According to 1-} xyN (0 ≦ x ≦ 1, 0 ≦ y ≦ 1, x + y ≦ 1), a double where a first conductivity type clad layer, an active layer and a second conductivity type clad layer are laminated in this order. It can be configured as having a heterostructure.
[0012]
The Ag-based contact layer and the Ag-based reflective metal layer may be formed directly on the main back surface of the light emitting layer portion, or may be formed on the auxiliary compound semiconductor layer made of the second compound semiconductor electrically coupled to the main back surface. It may be formed on the back surface. In this case, the auxiliary compound semiconductor layer must be transparent to the light from the light emitting layer so that the light from the light emitting layer can be guided to the Ag-based reflective metal layer. In this case, as the second compound semiconductor constituting the auxiliary compound semiconductor layer, one having a wider band gap than that of the first compound semiconductor constituting the light emitting layer portion, or one composed of an indirect transition type compound semiconductor is used. Is desirable.
[0013]
Although the auxiliary compound semiconductor layer may be formed as an epitaxial growth layer, there is a problem that it takes a long time to grow the auxiliary compound semiconductor layer to a considerable thickness in order to function as a reinforcing layer of the light emitting layer portion. Therefore, by forming the auxiliary compound semiconductor layer as a transparent conductive substrate bonded to the compound semiconductor layer for light emission, efficiency and simplification of the process can be achieved. In this case, the Ag-based reflective metal layer reflects the light from the light emitting layer toward the light extraction surface through the transparent conductive substrate.
[0014]
The Ag-based contact metal used for forming the Ag-based contact layer can be an AgGeNi contact metal containing Ag and Ge and Ni as main components.
[0015]
In addition, the ohmic electrode structure for a semiconductor device of the present invention may include an AgGeNi contact metal containing Ag and Ge as main components and a III-V compound semiconductor on a surface of an element body made of a III-V compound semiconductor. An Ag-based contact layer (hereinafter, also referred to as an AgGeNi contact layer) formed of an alloyed layer with the above is formed, and an electrode layer made of an Ag-based metal containing Ag as a main component is formed so as to cover the Ag-based contact layer. It is characterized by being done.
[0016]
Compound semiconductor layer is a group III-V compound semiconductor (the aforementioned _{(Al x Ga 1-x)} y In 1-y P ( However, 0 ≦ x ≦ 1,0 ≦ y ≦ 1) or _In x _Ga y _{Al 1-} When composed of _xy N (0 ≦ x ≦ 1, 0 ≦ y ≦ 1, x + y ≦ 1), the AgGeNi contact metal is a simple substance of Ni, Co, Mg and Sb disclosed in Patent Document 2. Compared to a metal for forming an ohmic contact, a much better ohmic contact is obtained, and the adhesion to the Ag-based reflective metal layer is high. The specific composition of the AgGeNi contact metal is, for example, Ge: 0.1% by mass to 25% by mass, Ni: 0.1% by mass to 20% by mass, and the balance: Ag. The reduction effect may not be sufficiently obtained.
[0017]
Note that the ohmic electrode structure for a semiconductor element of the present invention is not limited to the reflective metal layer of a light emitting element, but can be applied to an electrode of another semiconductor device such as a MESFET, HEMT, or HBT. It is economical to use inexpensive Ag as compared with Au-based electrodes that are usually used, and it is possible to obtain ohmic contact properties comparable to those of Au-based electrodes.
[0018]
In the light-emitting device of the present invention, it is preferable that an Ag-based contact layer is disposed between the Ag-based reflective metal layer and the transparent conductive substrate so as to be dispersed on the main surface of the Ag-based reflective metal layer. The Ag reflective metal layer forms a part of a current supply path to the light emitting layer. However, when the Ag-based reflective metal layer is directly joined to the light emitting layer portion made of a compound semiconductor, the contact resistance increases, the series resistance increases, and the luminous efficiency may decrease. In the case of the Ag-based reflective metal layer, the contact layer on the light-emitting layer portion side may be an Ag-based one instead of the Au-based one as in the related art, and the Ag-based reflective metal layer may be connected via the Ag-based contact layer. Thus, the contact resistance can be reduced by bonding to the light emitting layer portion, and the cost of forming the contact layer is lower than in the case where an Au-based contact layer is used. However, the Ag-based contact layer requires a relatively large amount of alloy components necessary for securing the bonding strength, and the reflectivity is slightly inferior. Therefore, if the Ag-based contact layer is dispersedly formed on the main surface of the Ag-based reflective metal layer, a high reflectance by the Ag-based reflective metal layer can be secured in a region where the Ag-based contact layer is not formed.
[0019]
In order to sufficiently enhance the light extraction effect, the formation area ratio of the Ag-based contact layer to the Ag-based reflection metal layer (the value obtained by dividing the formation area of the Ag-based contact layer by the total area of the Ag-based reflection metal layer). ) Is desirably 1% or more and 25% or less. If the area ratio of the Ag-based contact layer is less than 1%, the effect of reducing the contact resistance is not sufficient, and if it exceeds 25%, the reflection intensity is reduced.
[0020]
By setting the Ag-based reflective metal layer to have a higher Ag content than the Ag-based contact layer, the reflectivity of the Ag-based reflective metal layer can be further increased in a region where the Ag-based contact layer is not formed. As the material of the Ag-based reflective metal layer (and thus the first Ag-based metal layer and the second Ag-based metal layer), a metal having an Ag content of 95% by mass or more, more specifically, pure Ag (but 1% by mass) The above-mentioned effect can be further enhanced by adopting an unavoidable impurity as long as it is within the range. On the other hand, the Ag-based reflective metal layer can be made of an Ag alloy containing Pd. Ag alloys containing Pd have good sulfuration resistance and oxidation resistance, and can be deteriorated due to sulfurization or oxidation (degradation of reflectance when used as a reflective layer, when connecting to other electrical terminals as electrodes). Is effective in preventing an increase in contact resistance.
[0021]
In the present invention, as a specific method for forming the metal layer, in addition to a vapor phase film forming method such as vacuum evaporation or sputtering, it is also possible to employ an electrochemical film forming method such as electroless plating or electrolytic plating. it can.
[0022]
When the compound semiconductor layer is formed of (Al _x Ga _1-x ) _y In _1-y P (where 0 ≦ x ≦ 1, 0 ≦ y ≦ 1), the compound semiconductor layer is formed on the main surface on the bonding side. Preferably, an AgGeNi contact layer is formed, and a first Ag-based metal layer is formed so as to cover the AgGeNi contact layer. In this case, by performing the alloying heat treatment of the AgGeNi contact metal and the compound semiconductor layer at, for example, 350 ° C. or more and 660 ° C. or less, the effect of reducing the contact resistance is enhanced.
[0023]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
FIG. 1 is a conceptual diagram showing a light emitting device 100 according to one embodiment of the present invention. In the light emitting element 100, the light emitting layer 24 is provided on a main surface of a GaP substrate 7 made of an n-type GaP single crystal, which is a transparent conductive substrate, via a transparent conductive layer (for example, an ITO (Indium-Tin Oxide) layer) 30. It has a laminated structure.
[0024]
The GaP substrate 7 is manufactured by slicing and polishing a GaP single crystal ingot, and has a thickness of, for example, 100 μm or more and 500 μm or less. The main back surface of the GaP substrate 7 is covered with an Ag-based reflective metal layer 15 made of, for example, an Ag layer. Further, between the GaP substrate 7 and the Ag-based reflective metal layer 15, an AgGeNi contact metal (for example, Ge: 15% by mass, Ni: 10% by mass, the balance of Ag) and the surface of the GaP substrate 7 were alloyed. , An Ag-based contact layer 32 are arranged, which contributes to a reduction in series resistance of the element. The Ag-based contact layer 32, together with the Ag-based reflective metal layer 15 as an electrode layer and the GaP substrate 7 as an element body, constitute an ohmic electrode structure for a semiconductor element of the present invention. The AgGeNi contact layer 32 is dispersedly formed on the main surface of the Ag-based reflective metal layer 15, and the formation area ratio is 1% or more and 25% or less.
[0025]
Emitting layer 24, a non-doped _{(Al x Ga 1-x)} y In 1-y P ( However, 0 ≦ x ≦ 0.55,0.45 ≦ y ≦ 0.55) active layer 5 consisting of a mixed crystal , the first-conductivity-type cladding layer, in this embodiment the p-type cladding layer 6 made of p-type _{(Al z Ga 1-z)} y in 1-y P ( except x <z ≦ 1), wherein the first conductivity type the second-conductivity-type cladding layer different from the clad layer, in this embodiment interposed by an n-type _{(Al z Ga 1-z)} y in 1-y P ( except x <z ≦ 1) n-type cladding layer 4 made of The emission wavelength can be adjusted in the range from green to red (the emission wavelength (peak wavelength) is 550 nm or more and 670 nm or less) according to the composition of the active layer 5. To obtain, the peak wavelength is set in the range of 550 nm to 580 nm. In the light emitting device 100 of FIG. 1, the p-type AlGaInP cladding layer 6 is disposed on the metal electrode 9 side, and the n-type AlGaInP cladding layer 4 is disposed on the Ag-based reflective metal layer 15 side. Therefore, the polarity of the conduction is positive on the metal electrode 9 side. Here, “non-doped” means “do not actively add a dopant”, and contains a dopant component that is unavoidably mixed in a normal manufacturing process (for example, 10 ¹³ to 10 ¹⁶ / cm 3). ^The upper limit of about ³ ) is not excluded.
[0026]
A current diffusion layer 20 made of AlGaAs is formed on the main surface of the light emitting layer portion 24, and a metal electrode (for example, Au) for applying a light emission drive voltage to the light emitting layer portion 24 is provided substantially at the center of the main surface. An electrode 9 is formed so as to cover a part of the main surface. The area around the metal electrode 9 on the main surface of the current diffusion layer 20 forms a light extraction area from the light emitting layer section 24. The light from the light emitting layer portion 24 is extracted in such a manner that the light reflected directly by the Ag-based reflective metal layer 15 is superimposed on the light directly emitted to the light extraction surface side.
[0027]
The thickness of the Ag-based reflective metal layer 15 is desirably 80 nm or more in order to ensure a sufficient reflection effect. The upper limit of the thickness is not particularly limited, but is determined appropriately in consideration of cost (for example, about 1 μm) because the reflection effect is saturated.
[0028]
Hereinafter, a method for manufacturing the light emitting device 100 of FIG. 1 will be described.
First, as shown in Step 1 of FIG. 2, a p-type GaAs buffer layer 2 of, for example, 0.5 μm, AlAs is formed on a main surface of a GaAs single crystal substrate 1 which is a semiconductor single crystal substrate forming a light emitting layer growth substrate. The release layer 3 is epitaxially grown, for example, 0.5 μm, and the current diffusion layer 20 made of p-type AlGaAs, for example, 5 μm, in this order. Thereafter, a 1 μm p-type AlGaInP cladding layer 6, a 0.6 μm AlGaInP active layer (non-doped) 5, and a 1 μm n-type AlGaInP cladding layer 4 are epitaxially grown in this order. Then, as shown in Step 2, the transparent conductive layer 30 is formed on the side that becomes the main back surface after the formation of the light emitting layer portion 24.
[0029]
Then, as shown in Step 3, the main surface of the separately prepared GaP substrate 7 is overlapped with the transparent conductive layer 30 formed on the light emitting layer portion 24, pressed, and heat-treated at an appropriate temperature to be bonded. Then, a substrate bonded body 50 is made. Next, proceeding to step 4, the substrate bonded body 50 is immersed in an etching solution composed of, for example, a 10% hydrofluoric acid aqueous solution, and the AlAs release layer 3 formed between the buffer layer 2 and the light emitting layer portion 24 is selected. By etching, the GaAs single crystal substrate 1 (which is opaque to light from the light emitting layer portion 24) is peeled off from the stacked body 50a of the light emitting layer portion 24 and the GaP single crystal substrate 7 bonded thereto. . In addition, an etch stop layer made of AlInP is formed instead of the AlAs peeling layer 3, and a GaAs single crystal is formed using a first etching solution (for example, a mixed solution of ammonia / hydrogen peroxide) having a selective etching property for GaAs. The substrate 1 is removed by etching together with the GaAs buffer layer 2, and then an etch stop is performed using a second etching solution having a selective etching property for AlInP (for example, hydrochloric acid: hydrofluoric acid may be added to remove the Al oxide layer). A step of etching away the layer may be employed. As described above, the removal of the entire light emitting layer growth substrate by etching also belongs to the concept of “peeling”.
[0030]
Next, as shown in Step 5, an AgGeNi contact metal vapor-deposited layer is dispersedly formed on the main back surface of the GaP substrate 7, and alloying heat treatment is performed in a temperature range of 350 ° C. or more and 660 ° C. or less, so that the AgGeNi contact is formed. A layer 32 is formed. Thereafter, an Ag-based reflective metal layer 15 is formed so as to cover the AgGeNi contact layer 32. The AgGeNi contact layer 32 forms a good ohmic contact with the GaP substrate 7, and has high adhesion to the Ag-based reflective metal layer 15. In the above steps, each metal layer can be formed by using sputtering or vacuum evaporation. The alloying heat treatment may be performed after the formation of the Ag-based reflective metal layer 15.
[0031]
Then, as shown in Step 6, an electrode 9 for wire bonding (bonding pad: FIG. 1) is formed so as to cover a part of the main surface of the current diffusion layer 20 exposed by peeling of the GaAs single crystal substrate 1. . Thereafter, a semiconductor chip is diced by an ordinary method, and the semiconductor chip is fixed to a support, wire-bonded to a lead wire, and then sealed with a resin, thereby obtaining a final light emitting element.
[0032]
In the above embodiment, each layer of the light emitting layer portion 24 is formed of AlGaInP mixed crystal. However, each layer (the p-type cladding layer 6, the active layer 5, and the n-type cladding layer 4) is formed of AlGaInN mixed crystal. It can also be formed. As the light emitting layer growth substrate for growing the light emitting layer portion 24, for example, a sapphire substrate (insulator) or a SiC single crystal substrate is used instead of the GaAs single crystal substrate. When a light emitting layer portion made of an AlGaInN mixed crystal is formed on a sapphire substrate via a GaN buffer layer, the GaN buffer layer is dissolved by irradiating an excimer laser from the back side of the sapphire substrate, and the sapphire substrate is separated and removed. can do. When the emission wavelength of the light emitting layer portion 24 is 450 nm or more and 580 nm or less, the effect of improving the reflectance of blue or green light by employing the Ag-based metal layer 15 is great.
[0033]
Further, in the above embodiment, the layers of the light emitting layer portion 24 are arranged in the order of the n-type cladding layer 4, the active layer 5, and the p-type cladding layer 6 from the substrate side. The cladding, the active layer, and the n-type cladding layer may be formed in this order.
[Brief description of the drawings]
FIG. 1 is a schematic view showing one embodiment of a light-emitting element of the present invention in a laminated structure.
FIG. 2 is an explanatory view illustrating an example of a manufacturing process of the light emitting element of the present invention.
FIG. 3 is a diagram showing reflection spectra of various metals.
[Explanation of symbols]
1 GaAs single crystal substrate (substrate for light emitting layer growth)
4 n-type cladding layer (second conductivity type cladding layer)
5 Active layer 6 p-type cladding layer (first conductivity type cladding layer)
7 GaP substrate (transparent conductive substrate)
9 Metal electrode 15 Ag-based reflective metal layer 24 Light emitting layer 32 AgGeNi contact layer 100 Light emitting element

Claims (10)

While a light extraction surface is formed on the main surface side of the light emitting layer portion having a peak wavelength of 450 nm or more and 580 nm or less made of the first compound semiconductor, electric power is applied to the main back surface of the light emitting layer portion or the main back surface of the light emitting layer portion. An alloy of an Ag-based contact metal containing Ag as a main component and a compound semiconductor forming the main back surface is formed on the main back surface of the auxiliary compound semiconductor layer made of the second compound semiconductor transparent to the luminous flux, which is combined with the light emitting beam. An Ag-based contact layer made of a metal layer is formed, and further covers the Ag-based contact layer and reflects light from the light emitting layer portion toward the light extraction surface side, and is made of a metal containing Ag as a main component. A light emitting device comprising a reflective metal layer formed thereon. The light emitting layer _{portion, (Al x Ga 1-x} ) y In 1-y P ( However, 0 ≦ x ≦ 1,0 ≦ y ≦ 1) or _{In x Ga y Al 1-x} -y N (0 ≦ x ≦ 1, 0 ≦ y ≦ 1, x + y ≦ 1), the first conductivity type clad layer, the active layer, and the second conductivity type clad layer are configured as having a double hetero structure which is laminated in this order. The light emitting device according to claim 1, wherein The auxiliary compound semiconductor layer is a transparent conductive substrate bonded to the light emitting compound semiconductor layer, and the Ag-based reflective metal layer transmits light from the light emitting layer portion through the transparent conductive substrate to the light extraction surface. The light emitting device according to claim 1, wherein the light is reflected to a side. 4. The Ag-based contact layer is disposed between the Ag-based reflective metal layer and the transparent conductive substrate so as to be dispersed on a main surface of the Ag-based reflective metal layer. The light-emitting element according to any one of the preceding claims. The light emitting device according to claim 4, wherein a formation area ratio of the Ag-based contact layer to the Ag-based reflective metal layer is 1% or more and 25% or less. The light emitting device according to any one of claims 1 to 5, wherein the Ag-based reflective metal layer has a higher Ag content than the Ag-based contact layer. The light emitting device according to any one of claims 1 to 6, wherein the Ag content of the Ag-based reflective metal layer is 95% by mass or more. The light emitting device according to claim 7, wherein the Ag-based reflective metal layer is made of pure Ag. The light emitting device according to any one of claims 1 to 7, wherein the Ag-based reflective metal layer is made of an Ag alloy containing Pd. On the surface of an element body made of a III-V compound semiconductor, an AgGeNi contact metal containing Ag and Ge and Ni as main components and an Ag-based contact layer made of an alloyed layer of the III-V compound semiconductor are provided. An ohmic electrode structure for a semiconductor element, wherein an electrode layer made of an Ag-based metal containing Ag as a main component is formed so as to cover the Ag-based contact layer.

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