JPH11204887A - Semiconductor device having low resistance electrode - Google Patents

Abstract

PROBLEM TO BE SOLVED: To decrease an operating voltage and a threshold current of a GaN based compound semiconductor device, by selecting suitable contact metal, and bonding the metal to a P-GaN contact layer under suitable heat treatment conditions. SOLUTION: An ohmic electrode is composed of Pt contact metal 2 laminated on a P-GaN contact layer 1 and butt metal 3 composed of a thick Au film. The Pt contact metal 2 acts as a barrier to migration of the Au butt metal 3 to the P-type GaN contact layer 1. The Pt contact metal 2 does not act as a diffusion barrier to Ga, so that Ga diffuses from the surface of the P-GaN contact layer 1 to the inside of the Pt film 2. The surface of the P-GaN contact layer 1 where Ga diffuses to the outside and N is excessive acts as an excellent ohmic contact to the Pt contact metal 2, so that improvement effect of ohmic characteristic is remarkably obtained at a heat treatment temperature of 300 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device having a low-resistance electrode, and more particularly to a structure of a low-resistance ohmic electrode of a III-V compound semiconductor device containing Ga and N (nitrogen) in a composition. .

[0002]

2. Description of the Related Art Conventionally, a GaN-based semiconductor laser has been able to obtain a p-type crystal by adding Mg as an impurity, and is expected to be a semiconductor laser in the ultraviolet or blue region, and has been developed in many products. . However, although some laser emission was observed, there still remain many problems to be solved.

One of the major problems is that the operating voltage and the threshold current of laser emission are abnormally large. The reason is that GaN is a compound semiconductor having a large forbidden band width, and a contact metal having a large work function must be used to form a good ohmic electrode on the compound semiconductor. Also G
The work function difference between aN and the contact metal cannot be made sufficiently small.

Therefore, in particular, p-type GaN (hereinafter referred to as p-Ga
N) and the contact metal, a Schottky barrier was formed, and the ohmic characteristics were hindered. Here, the work function is the energy required to extract electrons from the substance to the outside.

Therefore, a metal such as Ni which is relatively easy to handle is usually used as a contact metal,
The failure to obtain a good ohmic contact has been neglected as an unavoidable problem due to the physical properties of GaN.

For example, H. Ishikawa et al .: J. Appl. Phy
s., 81 (1997) p1315, there have been many attempts to improve ohmic characteristics by heat treating metal electrodes, but good results have not been obtained for GaN.

In the case of n-GaN, it is extremely easy to obtain ohmic characteristics as compared with p-GaN.
In this case, the method of improving the ohmic characteristics is to make the electron concentration of the n-GaN contact layer which is the base of the contact metal extremely high, reduce the thickness of the Schottky barrier, and use the penetration of conduction electrons by the tunnel effect. Only.

However, at this time, for example, F. Chen et al .: E
electrochemical Society Proceedings, Vol. 96-11, (19
96) As shown in p122, n-GaN with high electron concentration
It is known that the crystal quality of the GaN layer adjacent to the contact layer is significantly reduced.

Further, for example, LLSmith et al .: J. Elect
As seen in ronic Matrials, Vol. 25 (1996) p805, a method of chemically treating the surface of GaN before depositing a contact metal has also been reported. At present, it is known that hydrofluoric acid (HF) -based surface treatment provides the best contact characteristics, but even with this method, an ohmic contact with sufficiently low resistance has not been obtained in practice.

As described above, the improvement of the ohmic contact characteristics with respect to p-type and n-type GaN is mainly achieved by increasing the dopant concentration of the contact layer or reducing the Schottky barrier height generated in the GaN contact layer. An intermediate layer having such a small band gap is formed by Ga
This has been done by providing between N and the contact metal. However, there are physical limitations in increasing the dopant concentration of p-type GaN, and no effective means has been found to overcome this.

It is noted that a large number of Ga-excess GaN surfaces are used in experiments for improving ohmic characteristics of GaN. However, this is not because the Ga-excess GaN surface is considered to be advantageous for improving the ohmic characteristics.
This is due to restrictions on crystal growth of the system. That is, at the crystal growth temperature, the dissociation pressure of N is much higher than the dissociation pressure of Ga, so that N is easily dissociated from GaN, and even if various measures are taken, this cannot be prevented.

Therefore, the obtained GaN is N-deficient (G
a excess). This problem is not only with GaN substrate crystals grown at high temperatures, but also with MOCs with lower growth temperatures.
The same applies to VD (abbreviation for Metal-Organic Chemical Vapor Deposition), MBE (abbreviation for Molecular Beam Epitaxy), and the like. For this reason, it has been considered very difficult to obtain an N-excess GaN layer.

[0013] In addition, the results of analysis performed by the inventor to clarify the problems that occur in the conventional GaN ohmic electrode using Ni as the contact metal will be described.
The p-GaN ohmic electrode shown in FIG.
A layer 11, a Ni film 12 serving as a contact metal, and Au
And a thick Au film 13 forming an Au pad used for wire bonding of fine wires.

The Ni / Au electrode for p-GaN exhibits ohmic characteristics when the two-layered metal film laminated on p-GaN is subjected to heat treatment. As shown in an X-ray photograph (by energy dispersive X-ray spectroscopy), a Ni film 12 ball-ups like a 14 inside a thick Au film 13 to form p-type GaN.
Is observed that 50% or more of the surface is directly covered with the Au film 13. Next, this phenomenon will be specifically described.

FIG. 9A is a characteristic X-ray image of Au from the cross section of the electrode after the excessive heat treatment. If such an excessive heat treatment is performed, Au penetrates into the place where the Ni film 12 was present, and directly joins with the p-GaN, and FIG.
It shows that the location indicated by the arrow as a ball-up is made of a material other than Au.

FIG. 9B shows a characteristic X-ray image of Ni obtained by using the same electrode cross section as a sample. FIG.
In (a), it is clearly shown that the material other than Au shown as the ball-up is made of Ni.

Since Au is one of the metals having a large work function, it seems to be advantageous as an ohmic contact of p-type GaN. However, Au easily penetrates into the GaN crystal and migrates through the crystal. Therefore, a leak path is generated inside the semiconductor device having the ohmic electrode, and the life of the semiconductor device is significantly reduced.

Oxygen penetrates into the Au film 13 from an oxide film or the like on the surface of the semiconductor device, so that the ball-up Ni,
Oxide 14 is converted into a high-resistance oxide, thereby shortening the life of the semiconductor device.

The ball-up of the Ni film, the change to the oxide, and the intrusion of Au into the p-type GaN are not necessarily caused by excessive heat treatment of the electrode, but also when the electrode is normal. It has been clarified by the inventor that if the electrode has a high resistance, the operating temperature rises due to Joule heat during the operation, and a similar phenomenon occurs due to the operation at a high temperature for a long time, thereby reducing the life of the device.

Further, if a shape change or a compound which cannot be explained by a simple diffusion phenomenon between the semiconductor and the contact metal is generated, a large strain is generated at the interface between the two and the brittleness is increased due to the compound generation. A minute crack is generated at the interface, and the ohmic resistance rapidly increases. Therefore, in order to obtain a long-life semiconductor device, it has been found that it is extremely important that no compound is formed between the semiconductor surface and the contact metal.

[0021]

As described above, in a conventional GaN-based semiconductor device, it is particularly difficult to form an ohmic contact of p-GaN, and p-GaN having a high dopant concentration necessary to reduce the ohmic contact is required. There was a problem that a contact layer could not be obtained.

The present invention has been made in order to solve the above-mentioned problems.
By forming an ohmic electrode having perfect ohmic characteristics without making the surface of the contact layer N-excessive and generating a high-resistance inclusion between the contact layer and the contact metal,
It is an object to reduce an operating voltage and a threshold current of an N-based compound semiconductor device.

[0023]

According to the GaN-based semiconductor device having a low-resistance electrode of the present invention, an appropriate contact metal is selected, an appropriate heat treatment condition is determined, and the GaN-based semiconductor device is joined to a p-GaN contact layer. Required N excess GaN
It is intended to obtain a surface.

That is, the type of contact metal to be joined to the p-GaN contact layer is selected so that Ga is easily diffused into the contact metal from the p-GaN surface, and a barrier metal is laminated on the contact metal. G diffusing from the p-GaN surface into the metal electrode
By controlling the a concentration profile and bringing the surface of the p-GaN contact layer into an appropriate N-rich (Ga-deficient) state without generating a high-resistance intermetallic compound at the interface, an electrode structure having good ohmic characteristics can be obtained. It is characterized by obtaining.

More specifically, the semiconductor device having a low-resistance electrode of the present invention has a composition containing at least Ga and N in a III-
V An electrode in which at least three metal films including a compound semiconductor layer, a contact metal bonded to the surface of the compound semiconductor layer, a barrier metal laminated thereon, and a pad metal adjacent thereto are laminated. With
In addition, the surface of the compound semiconductor layer containing Ga and N in the composition is N-excessive.

Here, the III-V compound semiconductor layer containing Ga and N in the composition includes, for example, GaN, Al _x Ga ₁ -xN (0 ≦
_{x ≦ 1), In x Ga} y Al z B 1-xyz N (0 ≦ x,
A GaN-based compound semiconductor layer such as y, z ≦ 1, 0 ≦ x + y + z ≦ 1).

Preferably, the contact metal includes at least one of Hf, Co, V, Cr, Ru, Rh, and Ir. Preferably, the barrier metal is at least Pt, W, Ta, M
o, Re, Os, Tc, and Zr.

[0028]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a semiconductor device having a low-resistance electrode according to an embodiment of the present invention will be described in detail with reference to the drawings. A first embodiment of the present invention will be described with reference to FIG. Note that in the first embodiment, Pt
The analysis result of the inventor about the deterioration mechanism of the Pt / Au electrode using as a contact metal will be described.

The ohmic electrode used for the analysis was p-Ga
It is composed of a Pt contact metal 2 laminated on the N contact layer 1 and a pad metal 3 made of a thick Au film. Since the Pt contact metal 2 forms a barrier against migration of the Au pad metal 3 to the p-type GaN contact layer 1, the lifetime is increased as compared with the conventional Ni / Au electrode of FIG.

The ohmic characteristics of the Pt / Au electrode are optimized by heat treatment at 300 ° C. Heat treatment temperature is 3
If the temperature exceeds 00 ° C., the ohmic characteristics deteriorate. FIG.
The reason will be described with reference to FIG.

FIG. 1B shows the concentration profile of the constituent elements inside the electrode after heat treatment at 300 ° C. or higher. The analysis method uses energy dispersive X-ray spectroscopy as in FIG. 9 and measures the detection intensity of characteristic X-rays of each element in the depth direction of the electrode.

As shown in FIG. 1B, since the Pt contact metal 2 does not act as a diffusion barrier for Ga,
Ga diffuses from the surface of the p-GaN contact layer 1 into the Pt film 2. Ga diffused to the outside and became N excess
-Since the surface of the GaN contact layer 1 becomes a good ohmic contact with the Pt contact metal 2,
At a heat treatment temperature of 300 ° C., the effect of improving the ohmic characteristics appears remarkably.

However, if the heat treatment temperature rises to 300 ° C. or more to cause more Ga diffusion, as shown by the arrow in the Ga concentration profile of FIG.
G at the interface between the contact layer 1 and the Pt contact metal 2
A layer having a very high a concentration is formed. That is, it was found that the high-concentration Ga diffused into the Pt contact metal 2 formed a high-resistance intermetallic compound Pt-Ga with Pt, and the resistance of the electrode portion increased.

Further, even if the heat treatment temperature is appropriate at 300 ° C., this intermetallic compound Pt—Ga grows on the electrode portion by heating at a high temperature for a long time by Joule heat during the operation of the semiconductor device, and the life of the semiconductor device is reduced. Was found to decrease.

Based on these findings, the following electrode structures of the second and third embodiments of the present invention were examined. A second embodiment of the present invention will be described with reference to FIG. The GaN-based semiconductor device according to the second embodiment includes:
About 10 nm thick on the clean p-type GaN contact layer 1
(V) contact metal 4 and a thick pad metal 3 made of Au.

The V contact metal 4 of FIG. 2A does not serve as a good diffusion barrier for Au as compared with the Pt contact metal 2 of FIG. Au diffusion occurs as shown in b).

The V / Au electrode was heated at a heat treatment temperature of 500 ° C.
Shows the best ohmic characteristics, but after the heat treatment at 500 ° C., the V contact metal 4 contains Au, and between the surface of the p-GaN contact layer 1 and the V contact metal 2, FIG. A) shown as an Au peak in
u pile-up occurs. Here, pile-up refers to a phenomenon in which elements carried by diffusion accumulate at the interface of joining of different materials with the passage of time.

As described above, the Au peak piled up at the interface between the p-GaN contact layer 1 and the V contact metal 4 easily penetrates into the p-GaN contact layer 1, Because of high reactivity, p-G
Excessive Ga is extracted from the surface of the aN contact layer 1 and is used as a source to diffuse Ga into the V contact metal 4, so that a diffusion profile consisting of a high concentration of Ga is obtained inside the V contact metal 4.

However, even if the heat treatment temperature is increased to 500 ° C. or higher, no abnormality indicating the formation of an intermetallic compound between V and Ga is found in the Ga diffusion profile inside the V contact metal 4. When the contact metal is V, a high-resistance intermetallic compound such as Pt is not formed with Ga, and the contact metal has a relatively low resistance even if a large amount of Ga ions diffuse. Turned out to be kept.

The peak of Au piled up between the p-GaN contact layer 1 and the V contact metal 4 indicates that Au does not have a brittle property and has a low resistance value.
It was found that the ohmic characteristics did not deteriorate.

Even if the heat treatment temperature is actually raised to 500 ° C. or more, the resistance value of the ohmic electrode made of V / Au according to the second embodiment is lower than that of the conventional Pt / Au ohmic electrode. Is shown. Therefore, as shown later,
The lifetime of a GaN-based semiconductor device having a V / Au electrode is P
The life time can be made longer than that provided with the t / Au electrode. However, also in this case, a large amount of Ga as an impurity penetrates into the contact metal with time,
A deterioration factor such as an increase in ohmic resistance remains.

Next, a third embodiment of the present invention will be described with reference to FIG. The ohmic electrode of the GaN-based semiconductor device according to the third embodiment has a V-contact metal 4 having a thickness of about 10 nm on a clean p-GaN contact layer 1.
And a Pt barrier metal 2 having a thickness of about 50 nm forming an Au diffusion barrier, and an Au pad metal 3.

By heat-treating the three-layer electrode of V / Pt / Au according to the third embodiment to 500 ° C., an ohmic electrode having low resistance and long life can be obtained.
That is, after the heat treatment, the diffusion of Au from the Au pad metal 3 to the V contact metal 4 is caused by the Pt barrier metal 2
Therefore, even after the heat treatment, the V-contact metal 4 remains Au like the V-contact metal 4 in FIG.
Is not included in a large amount. That is, the Pt barrier metal 2 acts as a diffusion barrier for Au.

As described above, since the V contact metal 4 containing no Au has a low bonding property with Ga ions, a large amount of Ga ions cannot be extracted from the surface of GaN, and p-
The surface of the GaN contact layer 1 acts as a controlled diffusion source of Ga into the V contact metal 4. Therefore, by optimizing the heat treatment conditions, an appropriate amount of Ga can be converted to p-GaN.
Diffusion from the surface of the contact layer 1 to the V-contact metal 4 can form an optimum N-excess state required for improving ohmic characteristics on the surface of the p-GaN contact layer 1.

As described above with reference to FIG. 1, since Pt forms an intermetallic compound Pt-Ga between Ga and Pt,
The bonding property with Ga is stronger than that of the contact metal 4. Therefore, the Ga diffused into the V contact metal 4
Piles up between the V contact metal 4 and the Pt barrier metal 2 as shown in FIG. 3 to form a Ga peak indicated by an arrow. Therefore, the concentration profile of Ga inside the V contact metal 4 determined by the law of diffusion is:
It shows a slope opposite to that of FIG.

Thus, the p-GaN contact layer 1
Is changed to an N-excess state, and a V-contact metal 4 having a low Ga content is bonded thereon.
P-G without forming high resistance intermetallic compound at the interface
By forming an ideal ohmic electrode for the aN contact layer, a GaN-based semiconductor device having a low operating voltage and a long life can be obtained.

N-excess p-GaN contact layer 1
The reason why the interface between the surface and the V contact metal 4 shows good ohmic characteristics will be described in more detail with reference to FIG.

As shown in FIG. 4A, if a V contact metal is formed on the surface of a p-GaN contact layer having a composition ratio of Ga and N of 1: 1 before heat treatment, the work function of the V contact metal can be improved. Is relatively small, p-Ga
A large Schottky barrier φ _B1 is formed for injection of holes into the N contact layer.

However, if the surface of the p-GaN contact layer becomes excessive in N after the heat treatment, the surface of the p-GaN becomes
Since a high-density surface state is formed by the a vacancy and the Fermi level of the V-contact metal is pinned to this high-density surface state, the height of the Schottky barrier is as shown in FIG.
A very small value compared to the phi _B1 as shown in the phi _B2 of (b). Therefore, good ohmic characteristics can be obtained with respect to the p-GaN contact layer even though the work function of the V contact metal is relatively small.

Here, the Fermi level means an energy level occupied by conduction electrons in the conduction band, and serves as a reference for the work function. Pinning to a surface state means that in the thermal equilibrium state, the Fermi energy of the contact metal matches the energy of the high-density surface state, and the height of the Schottky barrier does not depend on the work function of the contact metal. To be determined.

Next, the fourth embodiment of the present invention will be described with reference to FIGS.
As an embodiment, an example in which the ohmic electrodes of the second and third embodiments are applied to a GaN-based semiconductor laser device will be described. FIG. 5 shows a multiple quantum well structure (hereinafter referred to as MQ
W; a multi-quantum well)
FIG. 3 is a sectional view of an N-based semiconductor stripe laser.

The GaN-based stripe type semiconductor laser shown in FIG. 5 has a sapphire substrate 101, an n-GaN contact layer 102, and an Al / P layer formed on the contact layer.
an n-type ohmic electrode 103 made of t / Au;
An AlGaN (hereinafter, suffix representing composition is omitted) cladding layer 104, an n-GaN waveguide layer 105,
MQW active layer 106 made of InGaN, p-GaN
A waveguide layer 107, a p-AlGaN cladding layer 108,
p-GaN contact layer 109 and SiO ₂ for current confinement
Film 110 and p-type V / Pt / Au ohmic electrode 1
And 11.

The GaN-based isolated stripe type semiconductor laser shown in FIG. 6 is different from FIG. 5 in that a current block layer 112 composed of an n-GaN layer is used as an internal current confinement layer with a p-AlGaN cladding layer 108 and a p-GaN contact. This is disposed between the layer 109 and the layer 109. The other structure is the same as that of FIG.

The GaN-based semiconductor laser shown in FIG. 7 has a ridge-type stripe structure in which the current confinement is such that the upper portion of the p-AlGaN cladding layer 108 has a mesa structure. The insulating film 110 is a passivation film for protecting the mesa stripe and the like from external contamination. The other structures are the same as those in FIGS. 5 and 6, and a description thereof will be omitted.

In the semiconductor laser having the above-mentioned GaN-based multilayer structure, the V laser according to the second and third embodiments of the present invention is used.
/ Au or V / Pt / Au ohmic electrode is p-Ga
It is used as the ohmic electrode 111 on the N contact layer 109. FIGS. 5 to 7 show the case where V / Pt / Au electrodes are used. Conventionally, the Ni / Au electrode described with reference to FIG. 9 has been mainly used as the p-side ohmic electrode.

Next, based on FIG. 8, as a fifth embodiment of the present invention, a life test result of a GaN-based semiconductor laser having the ohmic electrodes described in the first to third embodiments will be described. A description will be given in comparison with a device having a Ni / Au electrode. In the fifth embodiment, the life characteristics are mainly determined by the structure of the p-side ohmic electrode, and it is understood that the difference between the other laser structures shown in FIGS. 5 to 7 is not particularly related to the life characteristics. Was.

As the ohmic electrode 111 on the p-type side, N
i / Au, Pt / Au, V / Au, and V / Pt / Au
FIG. 8 shows the results of a life test of a GaN-based semiconductor laser using electrodes. The GaN-based semiconductor laser used in the life test had an output of 3 mW at a temperature of 50 ° C., and the life test was performed by performing automatic power control (hereinafter referred to as APC).

Here, APC is a method in which a decrease in laser output is compensated for by an increase in operating current, and an increase in operating current over time is used as a measure of laser output reduction under a constant laser output condition. Therefore, if the operating current sharply increases, it is determined that the laser has failed.

From the life test results shown in FIG. 8, it was found that the laser of the Ni / Au electrode failed in 1500 hours. However, the laser of the Pt / Au electrode requires 4000 hours,
In the V / Au electrode according to the second embodiment of the present invention, 7000
It has been confirmed that the laser having the V / Pt / Au electrode according to the third embodiment of the present invention into which the Pt diffusion barrier is introduced has a lifetime of 10,000 hours or more.

The present invention is not limited to the above embodiment. For example, in the second and third embodiments, the V film is used as the contact metal. However, the same effect is obtained by, for example, Hf, Co, Cr, Pt, Ru, Rh, and Ir, or a multilayer film of these, or It can also be obtained by using an alloy film containing these metal elements. Although a Pt film was used as the diffusion barrier metal, the same effect was obtained by using, for example, W, Ta, Mo, Re, Os, Tc, and Zr, or a multilayer film of these, or an alloy film containing these metal elements. Can also be obtained.

The case where the contact layer serving as the base of the ohmic electrode made of the multilayer metal is made of p-GaN has been described.
Type III-V compound semiconductor layer, for example, Al _x Ga ₁ -xN
(0 ≦ x ≦ 1) 3-element compounds such as, In _x Ga _y Al _z
B _1-xyz N (0 ≦ x, y, z ≦ 1, 0 ≦ x + y + z ≦
The ohmic electrode of the present invention can be similarly used for quaternary compounds such as 1).

Although the GaN-based multi-layered semiconductor laser has been described as an object to which the ohmic electrode of the present invention is applied, the same effect is obtained by using a MES using a GaN-based multi-layered structure.
FET (Metal-Semiconductor Field Effect Transisto
r) etc. can be used for other active and passive elements. In addition, various modifications can be made without departing from the spirit of the present invention.

[0063]

As described above, the V / Au or V of the present invention
If a multi-layer ohmic electrode of / Pt / Au is used,
Conventionally, since a low-resistance ohmic electrode can be formed on a p-GaN contact layer where an excessive voltage is easily generated, a low-voltage operation and long-life GaN-based multilayer structure having a small threshold current for laser emission can be formed. A semiconductor device can be provided.

[Brief description of the drawings]

FIG. 1 is a diagram showing an internal structure of a Pt / Au electrode according to a first embodiment of the present invention, and FIG.
(B) is a view showing a profile of a constituent element after heat treatment.

FIG. 2 is a diagram showing an internal structure of a V / Au electrode according to a second embodiment of the present invention, wherein FIG. (B) is a view showing a profile of a constituent element after heat treatment.

FIG. 3 is a diagram showing the internal structure of a V / Pt / Au electrode according to a third embodiment of the present invention, and (a) is a cross-sectional view thereof.
(B) is a view showing a profile of a constituent element after heat treatment.

4A and 4B are diagrams showing a change in the height of a Schottky barrier with respect to a p-GaN contact layer before and after a heat treatment of a V contact metal according to the present invention. FIG. 4A is a band structure diagram showing a Schottky barrier before a heat treatment. (B) is a band structure diagram showing a Schottky barrier after heat treatment.

FIG. 5 is a diagram showing an example in which the V multilayer electrode of the present invention is applied to a GaN-based stripe laser.

FIG. 6 is a diagram showing an example in which the V multilayer electrode of the present invention is applied to a GaN-based isolated stripe laser.

FIG. 7 is a diagram showing an application example of a V multilayer electrode of the present invention to a GaN-based ridge laser.

FIG. 8 is a diagram showing a comparison between the lifetime of a GaN-based semiconductor laser having a V multilayer electrode of the present invention and the lifetime of a GaN-based semiconductor laser having a conventional electrode.

FIG. 9 is an X-ray photograph showing a change in the internal structure of a conventional Ni / Au electrode after heat treatment, in which (a) shows an Au image. (B) is a diagram showing a Ni image.

[Explanation of symbols]

1, 11: p-GaN contact layer 2: Pt contact metal 3, 13: Au pad metal 4: V contact metal 12: Ni film 14: ball-up Ni 101: sapphire substrate 102: n-GaN contact layer 103: Al / Pt / Au electrode 104 n-AlGaN cladding layer 105 n-GaN waveguide layer 106 InGaN MQW active layer 107 p-GaN waveguide layer 108 p-AlGaN cladding layer 109 p-GaN contact layer 110 SiO ₂ film 111 V / Pt / Au electrode 112 n-GaN current blocking layer

Claims (3)

[Claims] 1. III- containing at least Ga and N in a composition
V At least three metal films including a compound semiconductor layer, a contact metal bonded to the surface of the compound semiconductor layer, a barrier metal laminated on the contact metal, and a pad metal further laminated on the barrier metal. An electrode made of the compound semiconductor layer containing Ga and N in the composition.
A semiconductor device having a low-resistance electrode, which is characterized by being excessive. 2. The method according to claim 1, wherein the contact metal is at least H
2. The semiconductor device having a low-resistance electrode according to claim 1, wherein the semiconductor device includes any one of f, Co, V, Cr, Ru, Rh, and Ir. 3. The method according to claim 1, wherein the barrier metal is at least Pt,
2. The semiconductor device having a low-resistance electrode according to claim 1, wherein the semiconductor device includes any one of W, Ta, Mo, Re, Os, Tc, and Zr.