JPH10163529A - Gan compd. semiconductor element and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a transparent electrode from oxidation and obtain a light- emitting pattern stable in time and low drive voltage. SOLUTION: By vacuum evaporation, a Co layer is formed on the surface of a p<+> -layer 7, an Au layer is formed on the Co layer and heat treated to alloy these layers, thereby forming a transparent electrode 8A. The Au deposits on the Co to block the Co from oxidation, reduce the contact resistance of the electrode 8a and improve the transparency, thereby obtaining a light-emitting pattern which is stable in time. Co has a work function sufficiently high to obtain good ohmic characteristic.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a GaN-based compound semiconductor light emitting device and a method for manufacturing the same. In particular, p-type GaN
The present invention relates to an electrode material having a light-transmitting and ohmic characteristic for a system-based compound semiconductor light emitting device and a method for forming the electrode.

[0002]

2. Description of the Related Art Conventionally, in a compound semiconductor, an ohmic contact cannot be obtained only by forming a metal on the surface of the semiconductor. Therefore, an alloying treatment by heat treatment is performed to diffuse the metal into the semiconductor to form an ohmic contact. I'm trying to get. Even if a p-type GaN-based compound semiconductor is subjected to a resistance reduction treatment such as electron beam irradiation, its resistivity is higher than that of an n-type GaN-based compound semiconductor. There is almost no spread of the current to the electrode, and light is emitted only under the electrode. Therefore, nickel
An electrode having translucency and ohmic characteristics formed by laminating (Ni) and gold (Au) several tens of each and heat-treating the same has been proposed (JP-A-6-314822).

[0003]

However, an electrode formed by stacking several tens of nickel (Ni) and gold (Au) each and then heat-treating the electrode has good initial optical and electrical characteristics.
There has been a problem that the quality of the light emitting pattern deteriorates with time and the driving voltage increases. This is nickel (Ni),
It is considered that because gold (Au) is extremely thin, part of nickel (Ni) replaces gold (Au) during heat treatment, and nickel (Ni) appears on the electrode surface and oxidizes to form NiO. . That is, when electricity is supplied in this state, NiO 2 reacts with the OH ⁻ group of the water present around it, and a substance composed of NiOOH is formed by the reaction represented by the formula (1). This NiOOH is gold
Poor wettability with (Au) and GaN-based compound semiconductors, resulting in aggregation of NiOOH, deterioration of luminescence pattern quality over time, increase in contact resistance of electrodes, and deterioration of optical and electrical characteristics of devices. It is thought to decrease.

[0004]

[Number 1] ^{NiO + OH - → NiOOH + e} - ··· (1)

[0005] Accordingly, an object of the present invention is to solve the above problems,
An object of the present invention is to realize a GaN-based compound semiconductor light-emitting device which has translucency and ohmic characteristics, and whose light-emitting pattern and drive voltage are stable over time, and a method of manufacturing the same.

[0006]

According to the first aspect of the present invention, there is provided a cobalt (Co) alloy, palladium (Pd), or palladium (P).
d) Since a metal layer made of an alloy is formed on the p-type GaN-based compound semiconductor layer, a light-transmitting electrode for the semiconductor layer is formed. This makes it difficult for the elements constituting the electrode to be oxidized, thereby preventing the light-emitting pattern from changing over time due to the oxidation of the electrode, obtaining a light-emitting pattern that is stable over time, and reducing the contact resistance of the electrode.
A stable driving voltage can be obtained over time. In addition, since cobalt (Co) and palladium (Pd) are elements having a large work function, good ohmic characteristics can be obtained.

According to the second aspect of the present invention, cobalt
A first metal layer made of (Co) and a second metal layer made of gold (Au) laminated on the first metal layer, or a first metal layer made of gold (Au) and the first metal layer. A second metal layer composed of cobalt (Co) laminated on a metal layer of
A metal layer made of a cobalt (Co) alloy is formed by alloying the alloy layer with (Au) by heat treatment. Thus, if the electrode is cobalt (Co) alone, cobalt (Co)
Is easily oxidized, and the light emission pattern changes with time.By laminating a layer made of cobalt (Co) and a layer made of gold (Au) and performing a heat treatment, or an alloy of cobalt (Co) and gold (Au) By heat-treating, it is possible to prevent the oxidation of cobalt (Co), obtain an electrode having a small contact resistance, a stable light-emitting pattern over time, and an excellent light-transmitting property. Also, as in the invention according to claim 3, a first metal layer made of cobalt (Co), a second metal layer made of a Group 2 element laminated on the first metal layer, The third metal layer made of gold (Au) laminated on the second metal layer is alloyed by a heat treatment, or cobalt (Co) according to the invention of claim 4.
And a second metal layer made of an alloy of palladium (Pd) and platinum (Pt) laminated on the first metal layer is alloyed by heat treatment. In addition, an electrode having a small contact resistance, a stable light-emitting pattern over time, and an excellent light-transmitting property can be obtained, and an effect equivalent to that of the second aspect can be obtained. In addition, beryllium (Be), magnesium,
(Mg), calcium (Ca), strontium (Sr), barium
(Ba), zinc (Zn), cadmium (Cd) and the like are effective.

According to the present invention, the first metal layer made of palladium (Pd) and the second metal layer made of gold (Au) laminated on the first metal layer, or A first metal layer made of gold (Au) and a second metal layer made of palladium (Pd) laminated on the first metal layer are alloyed by heat treatment to form a palladium (Pd) alloy. Is formed. As a result, an electrode having a small transmissivity, a stable light-emitting pattern over time, and an excellent translucency can be obtained. Also, as in the invention according to claim 6, palladium (Pd)
6. The invention according to claim 5, wherein an alloy of platinum and platinum (Pt) is alloyed by heat treatment to obtain an electrode having a low contact resistance, a stable light-emitting pattern over time, and an excellent translucency. The same effect can be obtained.

According to the invention of claim 7, p-type GaN
The metal layer formed on the base compound semiconductor layer has a temperature of 400 ° C. to 700 ° C.
By heat treatment at a temperature of ° C., a well alloyed metal layer can be obtained, and an electrode having stable light emission and electrical characteristics can be obtained.

According to the present invention, the metal layer is subjected to a heat treatment under a low vacuum condition, so that the contact resistance of the metal layer can be further reduced. Here, the low vacuum condition means 10 Torr or less.

According to the ninth aspect of the present invention, the metal layer is heat-treated in an atmosphere containing at least a gas containing oxygen (O ₂ ) or oxygen (O), or as in the tenth aspect of the present invention. By heat-treating the metal layer under an inert gas atmosphere, without deteriorating the quality of the light-emitting pattern,
The contact resistance of the metal layer can be reduced. The atmosphere containing oxygen (O ₂ ) according to claim 9 is 100%
Oxygen (O ₂ ). Gases containing oxygen (O) include CO,
CO ₂ etc. The inert gas according to claim 10 includes nitrogen (N ₂ ), helium (He), neon (Ne), and argon.
(Ar) and krypton (Kr) are effective. Claim 1
By performing the heat treatment in the invention according to any one of claims 8 to 10 at 400 ° C. to 700 ° C. as in the invention described in claim 1, a better alloyed metal layer can be obtained, and the luminescence and An electrode having stable electric characteristics can be obtained.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First Embodiment Hereinafter, the present invention will be described based on specific embodiments. FIG. 1 is a schematic cross-sectional view of a light emitting device 100 formed on a sapphire substrate 1 and formed of a GaN-based compound semiconductor. A buffer layer 2 made of AlN is provided on a sapphire substrate 1, and a silicon (Si) -doped n-type Ga
An N layer 3 (n ⁺ layer) is formed. On this n ⁺ layer 3, a 0.5 μm syringe (Si) -doped n-type Al _0.1 Ga _0.9 N
A layer 4 (n-layer) is formed, and a 0.4 μm thick
An In _0.2 Ga _0.8 N layer 5 (active layer) is formed.
On this is formed a magnesium-doped (Mg) p-type Al _0.1 Ga _0.9 N layer 6 (p layer). On the p layer 6, a p-type GaN layer 7 (p ⁺ layer) doped with high concentration magnesium (Mg)
Are formed. A translucent electrode 8A formed by metal evaporation is formed on the p ⁺ layer 7, and an electrode 8B is formed on the n ⁺ layer 3. The translucent electrode 8A is composed of cobalt (Co) bonded to the p ⁺ layer 7 and a metal element described later such as gold (Au) bonded to cobalt (Co). The electrode 8B is made of aluminum (Al) or an aluminum alloy.

Next, a method of manufacturing the translucent electrode 8A of the light emitting device 100 will be described. Metalorganic vapor phase epitaxy
(MOVPE) to form the buffer layer 2 to the p ⁺ layer 7. Then, a mask is formed on the p ⁺ layer 7, the mask in a predetermined region is removed, and the portions of the p ⁺ layer 7, the p layer 6, the active layer 5, and the n layer 4 which are not covered with the mask are chlorine-free. Etching by reactive ion etching with gas containing
The surface of the n ⁺ layer 3 was exposed. Thereafter, the mask was removed. Next, the translucent electrode 8A was formed in the following procedure.

(1) A photoresist 9 is uniformly applied on the surface, and the photoresist 9 on the electrode forming portion on the p ⁺ layer 7 is removed by photolithography. As shown in FIG. The part 9A is formed. (2) On the exposed p ⁺ layer 7, 10 ^-6 To
A first metal layer 81 is formed as shown in FIG. 2 by depositing cobalt (Co) at a high vacuum of rr order or less at 40 °. (3) Subsequently, gold (Au) is deposited on the first metal layer 81 by 60 [deg.] To form a second metal layer 82 as shown in FIG. (4) Next, the sample is taken out of the vapor deposition apparatus, Co and Au deposited on the photoresist 9 are removed by a lift-off method, and a translucent electrode 8A for the p ⁺ layer 7 is formed. (5) When an electrode pad for bonding is formed on a part of the translucent electrode 8A, a photoresist is uniformly applied, and a window is opened in the photoresist at a portion where the electrode pad is formed. Next, cobalt (Co) or nickel (Ni)
And gold (Au), aluminum (Al), or their alloys to a thickness of about 1.5 μm by vapor deposition, and by vapor deposition on the photoresist by the lift-off method as in the process of (4). An electrode pad is formed by removing the film made of Co or Ni and Au, Al, or an alloy thereof. (6) Then, the sample atmosphere is evacuated with a vacuum pump, and N ₂ and O ₂
(1%) and supply a mixed gas to make it under atmospheric pressure, and in that state, raise the ambient temperature to about 550 ° C and heat for about 3 minutes.
The first metal layer 81 and the second metal layer 82 are alloyed.

However, this heat treatment can be performed under the following conditions. As the atmosphere gas, a gas containing at least one of N ₂ , He, O ₂ , Ne, Ar, and Kr can be used, and the pressure is arbitrary within a range from vacuum to a pressure exceeding atmospheric pressure. further,
The partial pressure of N ₂ , He, O ₂ , Ne, Ar, or Kr gas in the atmosphere gas is 0.01 to 1 atm, and even if the atmosphere gas is heated in a state sealed with the atmosphere gas or in a state in which the atmosphere gas is refluxed. good.

As a result of the above heat treatment after the lamination of cobalt (Co) and gold (Au), the first metal layer 8 of cobalt (Co) is formed.
The gold (Au) of the second metal layer 82 on the first layer is diffused into the p ⁺ layer 7 through the first metal layer 81 to form an alloy state with GaN of the p ⁺ layer 7. The translucent electrode 8 thus formed
When a current of 20 mA was applied to A, a driving voltage of 3.6 V was obtained, and it was confirmed that the contact resistance was sufficiently small.
Further, the translucent electrode 8A was uniformly formed on the entire surface of the p ⁺ layer 7, and a good surface state was obtained. In addition, the translucent electrode 8A
Since the second metal layer 82 is stacked on the first metal layer 81 made of cobalt (Co), the oxidation of cobalt (Co) is prevented, and the light emission pattern changes and light transmission due to the oxidation of cobalt (Co). It is possible to prevent a decrease in properties and an increase in contact resistance.
The translucent electrode 8A is made of cobalt (Co) having a large work function.
Since it is an alloy containing, good ohmic characteristics can be obtained. When an aging test was performed on the electrode 8A in a high-temperature, high-humidity atmosphere, the initial light-emitting pattern and driving voltage could be stably maintained even after 1000 hours.

In this embodiment, the conditions for alloying the first metal layer 81 of cobalt (Co) and the second metal layer 82 of gold (Au) are set in addition to the above conditions, and the sample atmosphere is set to a vacuum. Evacuate with a pump to create a low vacuum state, and in that state, ambient temperature is about 550 ° C
Under the condition of heating for about 3 minutes, and evacuating the sample atmosphere to vacuum, then supplying N ₂ at 3 liter / min to atmospheric pressure, and then setting the atmosphere temperature to about 550 ° C. The first metal layer 81 and the second metal layer 82 were alloyed under the condition of heating for about a minute, and the driving voltage of the obtained device was measured. The result is shown in FIG. 3 as case No. 1.

When the composition of the first metal layer 81 is gold (Au) and the composition of the second metal layer 82 is cobalt (Co) (Case No.
2) In the case where only the first metal layer 81 made of an alloy of cobalt (Co) and gold (Au) is used (case No. 3), the composition of the first metal layer 81 is cobalt (Co), and the composition of the first metal layer 81 is from magnesium (Mg). When a third metal layer made of gold (Au) is formed on the second metal layer 82 and the light-transmitting electrode has a three-layer structure (case No. 4),
When the composition of the metal layer 81 is cobalt (Co) and the composition of the second metal layer 82 is an alloy of palladium (Pd) and platinum (Pt)
(Case No. 5) was subjected to alloying treatment under the above three kinds of atmosphere conditions, and the driving voltage of the obtained device was measured. The result is shown in FIG. For the translucent electrode 8A
Figure 3 shows the evaluation of the drive voltage when a current of 20 mA flows.
Is shown in In FIG. 3, a mark indicates that the drive voltage is less than 4 V, and a mark indicates that the drive voltage is 5 V or more. In FIG. 3, the numerical value in parentheses of each metal layer indicates the film thickness (Å). Further, a continuous driving test was performed on all the above-mentioned element samples for 1000 hours in a high-temperature and high-humidity atmosphere. All of the device samples marked with “○” showed no change in driving voltage even after 1000 hours, no change in the light emission pattern, and stable characteristics both optically and electrically over time.

As shown in FIG. 3, in case No. 1, when the alloying process is performed by supplying only N ₂ without supplying O ₂ , the driving voltage when a current of 20 mA flows is 5 V As described above, the contact resistance increased. Further, when the alloying treatment was performed under a low vacuum condition, the driving voltage was reduced to less than 4 V, and the contact resistance was reduced. In case where the second metal layer 82 and a translucent electrode 8A made of cobalt (Co) the first metal layer 81 and gold made of (Au) as is the case No.1 is an atmosphere containing O ₂ and By performing the alloying treatment under a low vacuum condition, a light-emitting pattern and a low driving voltage that are stable over time can be obtained.

As shown in case No. 2 of FIG.
A second metal layer 82 on a first metal layer 81 made of gold (Au).
Alternatively, cobalt (Co) may be formed to a thickness of 60 °. In this case No. 2, similarly to case No. 1, by performing the alloying treatment under an atmosphere containing O ₂ and under a low vacuum condition, a light emission pattern and a low driving voltage that are stable over time can be obtained.
Further, as shown in Case No. 3 of FIG. 3, as the first metal layer 81, gold (Au) -cobalt (Co) having a film thickness of 100
It may be formed to a thickness of Å. In this case No. 3, the alloying process was performed in an atmosphere containing O ₂ and under a low vacuum condition as in the case of cases No. 1 and No. _2, thereby achieving a stable light-emitting pattern and low driving voltage over time. Is obtained. Further, as shown in Case No. 4 in FIG. 3, a second metal layer 82 is formed on the first metal layer 81 made of cobalt (Co) with a thickness of 20 °.
マ グ ネ シ ウ ム of magnesium (Mg) is stacked, and 60 膜厚 of gold (Au) is stacked on the second metal layer 82 to form the light-transmitting electrode 8A.
May have a three-layer structure. In this case No. 4, a stable light-emitting pattern and a low driving voltage with time can be obtained under any conditions including an O ₂ -containing atmosphere, a low vacuum condition, and an N ₂ atmosphere. As shown in case No. 5 of FIG. 3, palladium (Pd)-is formed as a second metal layer 82 on a first metal layer 81 made of cobalt (Co) having a thickness of 40 °.
Platinum (Pt) may be formed to a thickness of 80 ° by simultaneous vapor deposition. In this case No. 2, by performing the alloying treatment under a low vacuum condition and in an N ₂ atmosphere, a light emission pattern and a low driving voltage that are stable over time can be obtained.

As described above, the second metal layer 82 may be formed on the first metal layer 81 made of cobalt (Co), and the cobalt (Co) may be formed on the first metal layer 81 made of gold (Au). A second metal layer 82 made of the first metal layer 8 may be formed.
As 1, a gold (Au) -cobalt (Co) alloy may be formed.
In case No. 4 of the above embodiment, magnesium (M
g), but in addition to the above, a second group of beryllium (Be), calcium (Ca), strontium (Sr), barium (Ba), zinc (Zn), cadmium (Cd), etc. Elements may be used.

Second Embodiment In the first embodiment, the first metal layer 81 or the second metal layer 8 is used.
Although the configuration using cobalt (Co) for 2 was adopted, in this embodiment,
Instead of using cobalt (Co), the translucent electrode 8A is made of palladium.
It is characterized in that it is composed of a single layer of (Pd) or a palladium (Pd) alloy. The semiconductor element used has the same configuration as that of the first embodiment except for the composition of the translucent electrode 8A. Translucent electrode 8
FIG. 4 shows the relationship between the composition of A and the driving voltage when an alloying treatment was performed for each composition under the same conditions as in the first embodiment and a current of 20 mA was passed through the translucent electrode 8A. . Note that the evaluation criteria in FIG. 4 indicate that the drive voltage is less than 4 V, Δ indicates that the drive voltage is 4 V or more and less than 5 V, and X indicates that the drive voltage is 5 V or more. In all of the device samples of ○ and Δ, there was no change in the driving voltage even after 1000 hours, no change in the light emission pattern was observed, and stable characteristics were obtained both optically and temporally.

As can be seen from Case No. 1, palladium (Pd) having a thickness of 40 ° is formed on the p ⁺ layer 7 as the first metal layer 81, and 60 μm of gold is formed on the first metal layer 81. By forming the second metal layer 82 made of (Au) and performing alloying treatment under each condition, a stable light-emitting pattern and a low driving voltage of less than 4 V with time can be obtained, which is equivalent to that of the first embodiment. The effect of was able to be obtained. Since the translucent electrode 8A is an alloy of palladium (Pd) having a large work function, good ohmic characteristics were obtained as in the first embodiment. Also, Case No.2
As can be seen from FIG.
(Au) is formed on the p ⁺ layer 7, and a second metal layer 82 of palladium (Pd) having a thickness of 60 ° is formed on the first metal layer 81, and alloying is performed under each condition. As a result, a stable light emission pattern and a low driving voltage are obtained over time,
The same effect as No.1 was obtained.

In case Nos. 1 and 2, the transparent electrode 8A
Has a two-layer structure, but as shown in case No. 3, the translucent electrode 8A is formed into a single-layer structure with a thickness of 100 mm by simultaneous vapor deposition of palladium (Pd) and platinum (Pt). By performing the alloying treatment under the conditions, a stable light-emitting pattern and a low driving voltage over time were obtained. Further, as shown in Case No. 4, the light-transmitting electrode 8A was made of palladium (P
By d) forming a single-layer structure and performing alloying treatment under a low vacuum condition, a light emission pattern and a low driving voltage that were stable over time were obtained. In addition, a driving voltage of 4 V to 5 V was obtained by performing the alloying treatment in an N ₂ atmosphere. As described above, the translucent electrode 8A is made of palladium (Pd), gold (Au) or platinum.
By using an alloy structure with (Pt) or only palladium (Pd), a light emission pattern and a low driving voltage that were stable over time were obtained, and the same effect as that of the first example could be obtained.

In each of the above embodiments, the ambient temperature during the alloying treatment was set to about 550 ° C., but the temperature is not limited to this. The electrode does not exhibit ohmic characteristics when heat-treated at a temperature lower than 400 ° C, and when heat-treated at a temperature higher than 700 ° C, the contact resistance of the electrode increases and the surface morphology deteriorates. It is desirable to heat-treat. In each of the above embodiments, the light emitting element 1
00 has a single-layer active layer 5 made of In _0.2 Ga _0.8 N, but has a quaternary or ternary AlInGaN having an arbitrary mixed crystal ratio.
And, for example, it may be configured to include a light-emitting layer having a multiple quantum well or single quantum well structure made of In _0.2 Ga _0.8 N / GaN. Further, in the above embodiments, although the atmosphere containing O ₂ 1% as the atmosphere containing oxygen, or a 100% O ₂ atmosphere. Alternatively, the atmosphere may include a gas such as CO or CO ₂ .

The thickness of the light-transmissive electrode 8A including the first metal layer 81 and the second metal layer 82 is selected so as to obtain a light-transmitting property.
It is desirably in the range of 200 ° or less, and more preferably in the range of 15 to 150 ° from the viewpoint of adhesion and light transmission.

As indicated above, according to the present invention,
Prevents oxidation of electrodes by forming a metal layer made of cobalt (Co) alloy, palladium (Pd), or palladium (Pd) alloy as a light-transmitting electrode on the surface of a semiconductor made of p-type GaN compound In addition, it is possible to prevent a decrease in translucency due to oxidation of the electrode, to reduce the contact resistance of the electrode, and to obtain a light emitting pattern and a low driving voltage that are stable over time.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a structure of a light emitting device according to a first embodiment of the present invention.

FIG. 2 is a sectional view schematically showing the structure of an electrode on the surface of a p ⁺ layer.

FIG. 3 is a measurement diagram showing characteristics of the light-transmitting electrode of the light-emitting element according to the first embodiment of the present invention after the alloying treatment.

FIG. 4 is a measurement diagram showing characteristics of a light-transmitting electrode of a light-emitting element according to a second embodiment of the present invention after alloying processing.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Sapphire substrate 2 ... Buffer layer 3 ... n ⁺ layer 4 ... n layer 5 ... Active layer 6 ... p layer 7 ... p ⁺ layer 8A, 8B ... electrode 9A ... window part 81 ... 1st metal layer 82 ... 2nd metal Layer 100: GaN-based semiconductor light emitting device

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Naoki Shibata 1 Ochiai Nagahata, Kasuga-machi, Nishi-Kasugai-gun, Aichi Prefecture Inside Toyoda Gosei Co., Ltd. Address Toyoda Gosei Co., Ltd. (72) Inventor Masaki Murakami 22-32, Naganoya, Taki-cho, Tanabe-gun, Kyoto Prefecture, Japan Issue room

Claims (11)

[Claims] 1. A light emitting device having a p-type GaN-based compound semiconductor layer, wherein the electrode of the p-type GaN-based compound semiconductor layer comprises cobalt
A GaN-based compound semiconductor light-emitting device comprising a metal layer made of a (Co) alloy, palladium (Pd), or a palladium (Pd) alloy and having translucency and ohmic characteristics. 2. The metal layer made of a cobalt (Co) alloy includes a first metal layer made of cobalt (Co) and a second metal layer made of gold (Au) laminated on the first metal layer. A first metal layer composed of a metal layer or gold (Au) and a second metal layer composed of cobalt (Co) laminated on the first metal layer, or cobalt (Co) and gold (Au) The GaN alloy according to claim 1, wherein the alloy layer is a layer alloyed by heat treatment.
Based compound semiconductor light emitting device. 3. The metal layer made of the cobalt (Co) alloy includes a first metal layer made of cobalt (Co), and a second metal layer made of a Group 2 element stacked on the first metal layer. A third layer comprising a metal layer and gold (Au) laminated on the second metal layer;
2. The GaN-based compound semiconductor light emitting device according to claim 1, wherein the metal layer is a layer alloyed by heat treatment. 4. The metal layer made of the cobalt (Co) alloy includes a first metal layer made of cobalt (Co), and palladium (Pd) and platinum (Pt) laminated on the first metal layer. 2. The GaN-based compound semiconductor light-emitting device according to claim 1, wherein the second metal layer made of an alloy of (1) and (2) is a layer alloyed by heat treatment. 5. The metal layer made of the palladium (Pd) alloy includes a first metal layer made of palladium (Pd) and a second metal layer made of gold (Au) stacked on the first metal layer. A first metal layer made of a metal layer or gold (Au), and a second metal layer made of palladium (Pd) laminated on the first metal layer;
2. The GaN-based compound semiconductor light-emitting device according to claim 1, wherein the GaN-based compound semiconductor light-emitting device is alloyed by heat treatment. 6. The method according to claim 1, wherein the metal layer made of the palladium (Pd) alloy is a layer in which an alloy of palladium (Pd) and platinum (Pt) is alloyed by heat treatment. GaN-based compound semiconductor light emitting device. 7. The method for manufacturing a GaN-based compound semiconductor light-emitting device according to claim 1, wherein the electrode is formed by heat-treating the metal layer at 400 ° C. to 700 ° C. 8. The GaN-based compound semiconductor light emitting device according to claim 1, wherein the metal layer is subjected to the heat treatment under a low vacuum condition to form the electrode according to claim 1. Production method. 9. The electrode according to claim 2, 3 or 5, wherein the metal layer is heat-treated in an atmosphere containing at least oxygen (O ₂ ) or a gas containing oxygen (O). A method for manufacturing a GaN-based compound semiconductor light-emitting device, comprising: 10. The GaN-based compound semiconductor light-emitting device according to claim 3, wherein the metal layer is subjected to the heat treatment in an inert gas atmosphere to form the electrode according to claim 3. Manufacturing method. 11. The method according to claim 8, wherein the heat treatment is performed at 400 ° C. to 700 ° C.