JP2003031894A - Semiconductor laser and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor laser using a nitride semiconductor capable of easily raising the output and to provide a method for manufacturing the same. SOLUTION: The semiconductor laser comprises a P-type side ohmic electrode 52 brought into ohmic contact with a P-type contact layer 43 in other region except at least one end of a resonator direction A, and a P-type side Schottky electrode 53 brought into Schottky contact with the layer 43 at its end. Thus, at least one end of the direction A is set to a current non-implanting region, a surface area of the electrode 53 is increased, and a contact resistance with the wirings can be decreased. Further, heat generated particularly near resonator end faces 10a, 10b of an active layer 30 can be efficiently radiated. The width of the ends in the resonator direction in which the layer 43 is brought into contact with the electrode 53 is preferred to be 50 μm or less.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor laser provided with an n-type semiconductor layer, an active layer and a p-type semiconductor layer each made of a nitride semiconductor, and a method for manufacturing the same.

[0002]

2. Description of the Related Art In recent years, in optical disk devices, magneto-optical disk devices, etc., there is an increasing demand for higher density recording / reproducing or higher resolution.
BACKGROUND ART Research and development of semiconductor lasers (laser diodes; LDs) capable of emitting light in a short wavelength region such as a blue wavelength region or an ultraviolet region have been actively conducted. Materials suitable for constructing a semiconductor laser capable of emitting light in such a short wavelength range include GaN and A.
Nitride semiconductors represented by lGaN mixed crystal or GaInN mixed crystal are known. In order to realize recording / reproduction of a rewritable disc by a semiconductor laser using this nitride semiconductor, a large optical output of at least about 30 mW is required.

In order to realize high output of light in this type of semiconductor laser, optical damage (catastrophic) that occurs in the vicinity of a pair of end faces opposed to each other in the cavity direction.
Optical Damage (COD) must be suppressed. In this COD, non-radiative recombination of electrons and holes occurs more in the vicinity of the end face where a high-density interface state exists than in the inside, the carrier density decreases, and light is absorbed in the vicinity of the end face. It is known that this is caused by a series of phenomena in which as the temperature rises, the band gap decreases, light absorption occurs, and the temperature further rises.

As one of means for solving such a problem, a p-side ohmic electrode provided on the p-type semiconductor layer for supplying a current to the active layer and a p-side ohmic electrode for wiring the element are provided. There is proposed a gallium nitride-based semiconductor laser in which the length of the p-side Schottky electrode provided on the cavity in the cavity direction is shorter than the cavity length.

[0005]

However, in such a semiconductor laser, since the surface area of the p-side Schottky electrode is small, the contact area with the wiring is small and the contact resistance is large. Therefore, particularly in the case of achieving high output, there are problems that the driving voltage becomes large, the power consumption becomes large, and the amount of heat generation at the contact portion with the wiring becomes large. Further, since the p-side ohmic electrode and the p-side Schottky electrode are not in contact with each other in the vicinity of the end portion in the cavity direction, it is difficult to efficiently dissipate heat generated in the active layer to the outside, and optical damage due to temperature rise occurs. There was also the problem that it would be easier.

The present invention has been made in view of the above problems, and an object thereof is to provide a semiconductor laser using a nitride semiconductor and a method for manufacturing the same, which can easily achieve high output.

[0007]

A semiconductor laser according to the present invention is a semiconductor laser provided with an n-type semiconductor layer, an active layer and a p-type semiconductor layer each made of a nitride semiconductor, and at least one of them in the cavity direction. P in ohmic contact with the p-type semiconductor layer in regions other than the ends
The side ohmic electrode and the p-side Schottky electrode that is in Schottky contact with the p-type semiconductor layer at at least one end in the cavity direction are provided.

A method of manufacturing a semiconductor laser according to the present invention is
A semiconductor laser having an n-type semiconductor layer, an active layer, and a p-type semiconductor layer each made of a nitride semiconductor, wherein the p-type semiconductor layer is formed in a region other than at least one end in the cavity direction. And a step of forming a p-side Schottky electrode in Schottky contact with the p-type semiconductor layer at at least one end in the cavity direction.

In the semiconductor laser according to the present invention, since the p-side Schottky electrode is in Schottky contact with the p-type semiconductor layer at at least one end in the cavity direction, the contact area with the wiring becomes large and the contact resistance is increased. Becomes smaller. Therefore, the driving voltage becomes smaller and the amount of heat generation at the contact portion with the wiring becomes smaller. Further, the heat generated in the active layer, particularly the heat generated at the end portion in the resonator direction, is efficiently released. Therefore, it is possible to increase the output while preventing optical damage to the end portion in the resonator direction.

In the method of manufacturing a semiconductor laser according to the present invention, the p-side ohmic electrode is formed so as to make ohmic contact with the p-type semiconductor layer in the region other than at least one end in the cavity direction. Further, the p-side Schottky electrode is formed so as to make a Schottky contact with the p-type semiconductor layer at at least one end in the cavity direction.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below in detail with reference to the drawings.

[First Embodiment] FIG. 1 shows a structure of a semiconductor laser 10 according to a first embodiment of the present invention. This semiconductor laser 10 has an n-type semiconductor layer 20, which is laminated on one surface of a substrate 11 in order from the substrate 11 side.
It has an active layer 30 and a p-type semiconductor layer 40. The substrate 11 has, for example, sapphire (α-Al ₂ ) having a thickness (hereinafter, simply referred to as thickness) in the stacking direction of about 80 μm.
O ₃ ), and the n-type semiconductor layer 20, the active layer 30, the p-type semiconductor layer 40, etc. are formed on the c-plane of the substrate 11. The n-type semiconductor layer 20, the active layer 30, and the p-type semiconductor layer 40 contain at least one of Group 3B elements in the short-periodic periodic table and at least nitrogen of Group 5B elements in the short-periodic periodic table. And a nitride semiconductor containing

The n-type semiconductor layer 20 has, for example, an n-side contact layer 21, an n-type clad layer 22 and an n-type guide layer 23 which are sequentially stacked from the substrate 11 side. The n-side contact layer 21 has, for example, a thickness of 3 μm, and
It is composed of n-type GaN to which silicon (Si) is added as a type impurity. The n-type cladding layer 22 is, for example,
It has a thickness of 1 μm and is composed of an n-type AlGaN mixed crystal to which silicon is added as an n-type impurity. The n-type guide layer 23 has, for example, a thickness of 0.1 μm, and is made of n-type GaN doped with silicon as an n-type impurity.

The active layer 30 has, for example, a thickness of 30 nm and has different compositions of Ga _x In _{1 -x} N (where x ≧ 0).
It has a multiple quantum well structure in which mixed crystal layers are stacked.

The p-type semiconductor layer 40 is, for example, the active layer 30.
It has a p-type guide layer 41, a p-type clad layer 42, and a p-side contact layer 43 which are sequentially stacked from the side. p
The mold guide layer 41 has, for example, a thickness of 0.1 μm,
It is composed of p-type GaN to which magnesium (Mg) is added as a p-type impurity. The p-type cladding layer 42 is
For example, it has a thickness of 0.8 μm and is composed of a p-type AlGaN mixed crystal to which magnesium is added as a p-type impurity. The p-side contact layer 43 has, for example, a thickness of 0.5 μm and is made of p-type GaN to which magnesium is added as a p-type impurity. A part of the p-type cladding layer 42 and the p-side contact layer 43 are thin strips extending in the cavity direction A, and are configured to perform current constriction.

In this semiconductor laser 10, the n-side contact layer 2 in the direction perpendicular to the cavity direction A is formed.
The width of one of the other n-type cladding layers 22 and n-type guide layers 2
3. It is wider than the active layer 30 and the p-type semiconductor layer 40, and the n-type clad layer 22, the n-type guide layer 23, the active layer 30 and the p-type semiconductor layer 40 are laminated on a part of the n-side contact layer 21. Has been done.

On the surface of the n-side contact layer 21 and the surface of the p-type semiconductor layer 40, for example, silicon dioxide (Si
An insulating film 12 made of O ₂ ) is formed. The insulating film 12 is provided with openings corresponding to the n-side contact layer 21 and the p-side contact layer 43, respectively. n
An n-side electrode 51 is formed on the side contact layer 21 corresponding to this opening. The n-side electrode 51 has, for example, a structure in which titanium (Ti), platinum (Pt), and gold (Au) are sequentially stacked, or a structure in which aluminum (Al), platinum, and gold are sequentially stacked and alloyed by heat treatment. And is in ohmic contact with the n-side contact layer 21.

The insulating film 1 is formed on the p-side contact layer 43.
The p-side ohmic electrode 52 and p corresponding to the second opening.
Side Schottky electrodes 53 are formed respectively. p
The side ohmic electrode 52 is, for example, palladium (Pd),
The p-type semiconductor layer 40 has a structure in which platinum (Pt) and gold are sequentially stacked, and is formed in at least one end portion in the resonator direction A, for example, in other regions except both end portions.
Specifically, it is in ohmic contact with the p-side contact layer 43. The p-side Schottky electrode 53 has a structure in which, for example, titanium, platinum and gold are sequentially stacked. The p-side Schottky electrode 53 is provided so as to cover the entire p-side ohmic electrode 52, and is in ohmic contact with the p-side ohmic electrode 52.

As a result, at least one end of the active layer 30 in the cavity direction A is a current non-injection region, and the current injection region of the active layer 30 functioning as a light emitting portion is in the cavity direction A. It is a portion corresponding to the p-side contact layer 43 in other regions except at least one end. Here, the current non-injection region does not mean a region in which no current flows, but a region in which no current is positively injected. The width of the current non-injection region in the cavity direction A, that is, the p-side ohmic electrode 5
2 is not in contact with the end portion 43a of the p-side contact layer 43
The width of is preferably within 50 μm. If it is larger than that, the contact portion between the p-side ohmic electrode 52 and the p-side contact layer 43 decreases, and the driving voltage increases, and at the same time, the current flows from the p-side ohmic electrode 52 to the p-side contact layer 43 uniformly. This is because the threshold current is increased without being injected.

The p-side Schottky electrode 53 is in Schottky contact with the p-type semiconductor layer 40, specifically the p-side contact layer 43, at least at one end in the cavity direction A. As a result, the area of the p-side Schottky electrode 53 can be increased, and the contact resistance with the wiring (not shown) electrically connected to the external power supply can be reduced. The width of the p-side Schottky electrode 53 in the direction perpendicular to the cavity direction A is preferably wider than the opening of the insulating film 12. This is because the area of the p-side Schottky electrode 53 can be made wider and the contact resistance with the wiring can be made lower. Like the p-side Schottky electrode 53, the width of the p-side ohmic electrode 52 in the direction perpendicular to the cavity direction A may be wider than the opening of the insulating film 12.

In this semiconductor laser 10, the pair of side surfaces facing each other in the cavity direction A is the cavity end surface 10.
a, 10b, and the pair of resonator end faces 10a, 1
A pair of reflecting mirror films (not shown) are respectively formed on 0b. The reflectance is adjusted so that one of the pair of reflecting mirror films has a low reflectance and the other has a high reflectance. As a result, the light generated in the active layer 30 is amplified by traveling back and forth between the pair of reflecting mirror films,
A laser beam is emitted from the low-reflectance mirror film. The p-side ohmic electrode 52 has a p-type in the region other than one end in the cavity direction A.
When it is in ohmic contact with the type semiconductor layer and only one end is the current non-injection region, it is preferable that the side of the current non-injection region is a reflection mirror film having a low reflectance. This is because optical damage can be prevented more effectively.

The semiconductor laser 10 having such a structure
Can be manufactured as follows. Here, a case of manufacturing a plurality of semiconductor lasers 10 will be described as an example.

2 to 4 show the manufacturing process for one semiconductor laser forming region. Note that FIG.
FIGS. 3A and 3B and FIG. 3A show a sectional structure perpendicular to the cavity direction A, and FIGS. 3B and 4 show the p-side contact layer 43 along the cavity direction A. It shows a cross-sectional structure cut so as to include. First, for example, a substrate 11 having a plurality of semiconductor laser forming regions and having a thickness of about 400 μm and made of sapphire is prepared. Then
As shown in FIG. 2 (A), for example, MOCVD (Metal Organic Chemical Vapor) is formed on the c-plane of the substrate 11, for example.
Deposition: n-type contact layer 21 made of n-type GaN, n-type AlGaN by metalorganic chemical vapor deposition)
N-type cladding layer 22 made of mixed crystal, n-type guide layer 23 made of n-type GaN, active layer 3 made of GaInN mixed crystal
0, p-type guide layer 41 made of p-type GaN, p-type AlG
p-type cladding layer 42 made of aN mixed crystal and p-type GaN
The p-side contact layer 43 is sequentially grown.

When MOCVD is performed, the source gas of gallium is, for example, trimethylgallium ((CH ₃ )
₃ Ga), aluminum source gas is, for example, trimethyl aluminum ((CH ₃ ) ₃ Al), and indium source gas is, for example, trimethyl indium ((C
As the source gas for H ₃ ) ₃ In) and nitrogen, for example, ammonia (NH ₃ ) is used. Also, for example, monosilane (SiH ₄ ) is used as the silicon source gas, and bis = cyclopentadienyl magnesium ((C ₅ H ₅ ) ₂ Mg) is used as the magnesium source gas.

After growing the p-side contact layer 43,
For example, a stripe-shaped mask (not shown) made of silicon dioxide is formed on the p-side contact layer 43 by vapor deposition. Next, as shown in FIG. 2B, a part of the p-side contact layer 43 and the p-type cladding layer 42 is selectively etched by RIE (Reactive Ion Etching) using this mask, and p The upper part of the mold cladding layer 42 and the p-side contact layer 43 are formed into a thin strip shape.

After that, the mask not shown is removed, and, for example, the p-side contact layer 43 and the p-type cladding layer 42 are removed.
A mask (not shown) made of silicon dioxide is selectively formed on the above by vapor deposition. Then, as shown in FIG. 3A, the p-type cladding layer 4 is formed using this mask.
2, p-type guide layer 41, active layer 30, n-type guide layer 2
3, The n-type cladding layer 22 and a part of the n-side contact layer 21 are sequentially etched by RIE or the like to expose the n-side contact layer 21 on the surface.

After exposing the n-side contact layer 21,
The mask (not shown) is removed, and the insulating film 12 made of silicon dioxide is formed on the entire surface (that is, on the n-side contact layer 21, the p-type cladding layer 42, and the p-side contact layer 43) by, for example, a vapor deposition method. After the insulating film 12 is formed, the insulating film 12 is selectively removed by etching using, for example, a lithography technique, and the p-side contact layer 43 is formed.
A striped opening corresponding to the above is formed in the insulating film 12.

After forming an opening in the insulating film 12, a resist film (not shown) is formed on the entire surface (that is, on the insulating film 12 and the p-side contact layer 43) to correspond to the formation position of the p-side ohmic electrode 52. A resist pattern (not shown) having openings is prepared. That is, in the resist film (not shown), in the resonator direction A corresponding to the opening of the insulating film 12.
An opening is formed in a region other than at least one end of the opening. After that, the entire surface (that is, on the resist film (not shown) and the exposed p-side contact layer 43)
Then, for example, palladium, platinum, and gold are sequentially vapor-deposited, and a resist film (not shown) is removed (lifted off) together with each metal vapor-deposited thereon. As a result, as shown in FIG. 3B, the p-side ohmic electrode 52 that makes ohmic contact with the p-side contact layer 43 in the region other than at least one end portion in the resonator direction A is formed, and p The end 43a of the side contact layer 43 is exposed.

After forming the p-side ohmic electrode 52,
For example, a resist film (not shown) is formed on the entire surface (that is, on the insulating film 12, the p-side ohmic electrode 52, and the end portion 43a of the p-side contact layer 43), and the n-side electrode 51 and the p-side Schottky electrode 53 are formed. A resist pattern (not shown) having openings corresponding to the positions is prepared. That is, the p-side ohmic electrode 5 is formed on the resist film (not shown).
2 and the opening is formed so that the end portion 43a of the p-side contact layer 43 is exposed, and the opening corresponding to the n-side contact layer 21 is formed. After that, the insulating film 1 is etched by, for example, etching using a resist film (not shown) as a mask.
2 is selectively removed to expose a part of the n-side contact layer 21.

After exposing a part of the n-side contact layer 21, for example, titanium, platinum, and gold are sequentially deposited on the entire surface (that is, on the region exposed by the resist film and the opening (not shown)), and then, not shown. The resist film is removed (lifted off) together with each metal vapor-deposited thereon. Thereby, as shown in FIG. 4, the p-side Schottky electrode 53 and the n-side electrode 51 are formed.

After forming the n-side electrode 51 and the p-side Schottky electrode 53, the substrate 11 is ground to have a thickness of, for example, about 80 μm. Next, the substrate 11 is cleaved in the space area of the p-side ohmic electrode 52 perpendicularly to the resonator direction A and divided. As a result, the resonator end faces 10a and 10b are formed. After cleaving, reflecting mirror films (not shown) are respectively formed on the resonator end faces 10a and 10b. After that, the substrate 11 is divided in parallel with the cavity direction A so as to correspond to the formation region of each semiconductor laser 10. As a result, a plurality of semiconductor lasers 10 shown in FIG. 1 are completed.

The semiconductor laser 10 operates as follows.

In this semiconductor laser 10, the n-side electrode 51
When a predetermined voltage is applied between the p-side Schottky electrode 53 and the p-side Schottky electrode 53, a current is injected into the active layer 30 and electron-hole recombination causes light emission. This light is reflected by a reflecting mirror film (not shown) and reciprocates between them to generate laser oscillation,
It is emitted to the outside as a laser beam. In the present embodiment, since the p-side ohmic electrode 52 makes ohmic contact with the p-side contact layer 43 in the region other than at least one end portion in the resonator direction A, the active layer 30.
At least one end portion in the resonator direction A is a current non-injection region. Therefore, by preventing non-radiative recombination in at least one of the resonator end faces 10a and 10b and the region in the vicinity thereof, an increase in temperature is suppressed and optical damage is prevented.

Further, in this embodiment, the p-side Schottky electrode 53 is provided so as to cover the p-side ohmic electrode 52, and the p-side contact layer 43 and the Schottky contact are provided at least at one end in the resonator direction A. Therefore, the surface area of the p-side Schottky electrode 53 is large. Therefore, the contact resistance with the wiring is reduced, the driving voltage is reduced, and the amount of heat generated in the contact portion with the wiring is also reduced. Further, the heat generated in the active layer 30, particularly the heat generated in the vicinity of the resonator end faces 10a and 10b, is efficiently released, and the optical damage due to the temperature rise is more effectively prevented.

As described above, according to the present embodiment, the p-side ohmic electrode 52 which makes ohmic contact with the p-side contact layer 43 in the region other than at least one end in the resonator direction A, and the end thereof. Since the p-side contact layer 43 and the p-side Schottky electrode 53 in Schottky contact are provided, at least one end of the p-side Schottky electrode 53 serves as a current non-injection region and the surface area of the p-side Schottky electrode 53 is increased. The contact resistance with the wiring can be reduced. Therefore, it is possible to reduce the driving voltage and the power consumption while preventing the optical damage at the end portion, and to reduce the heat generation amount in the contact portion with the wiring. Further, the heat generated in the active layer 30, particularly the heat generated in the vicinity of the resonator end faces 10a and 10b, can be efficiently released, and the optical damage can be prevented more effectively. Therefore, high output can be easily achieved.

Further, according to the method of manufacturing the semiconductor laser of the present embodiment, the n-side electrode 51 and the p-side Schottky electrode 52 are formed in the same process, so that the manufacturing process can be simplified. Therefore, the manufacturing efficiency can be improved.

[Second Embodiment] FIG. 5 shows a structure of a semiconductor laser 60 according to a second embodiment of the present invention. This semiconductor laser 60 has the same configuration, action, and effect as those of the first embodiment except that the insulating film 12 is removed and the p-side ohmic electrode 52 and the p-side Schottky electrode 53 have different shapes. ing. Therefore,
Here, the same components are denoted by the same reference numerals, and detailed description thereof will be omitted.

The p-side ohmic electrode 52 and the p-side Schottky electrode 53 are the same as the p-side contact layer 43 except that the width in the direction perpendicular to the cavity direction A is substantially the same. It has the same configuration as the embodiment.

A semiconductor laser 60 having such a structure
Can be manufactured as follows.

FIG. 6 and FIG. 7 show the manufacturing process for one semiconductor laser forming region. In addition,
6 (A), (B) and FIG. 7 (B) show a sectional structure perpendicular to the resonator direction A, and FIG. 7 (A) shows the p-side contact layer 43 along the resonator direction A. The cross-sectional structure cut so as to include is shown. First, similarly to the first embodiment, the n-type semiconductor layer 2 is formed on the c-plane of the substrate 11, for example.
0, the active layer 30, and the p-type semiconductor layer 40 are sequentially grown. Next, as shown in FIG. 6A, for example, a stripe-shaped metal film pattern 52a made of palladium, platinum, and gold is formed on the p-side contact layer 43 by an evaporation method or the like. The material configuration of the metal film pattern 52a is not limited to this combination as long as it has resistance to etching such as RIE.

Subsequently, as shown in FIG. 6B, using the metal film pattern 52a as a mask, the p-side contact layer 43 and a part of the p-type cladding layer 42 are selectively etched by RIE or the like, and p The upper part of the mold cladding layer 42 and the p-side contact layer 43 are formed into a thin strip shape.

After that, for example, a mask (not shown) made of silicon dioxide is selectively formed on the entire surface (that is, on the p-type cladding layer 42 and the metal film pattern 52a) by a vapor deposition method. Then, as shown in FIG.
Using a mask (not shown), at least one end of the metal film pattern 52a in the cavity direction A is selectively etched with aqua regia, and the p-side ohmic electrode 52 is formed.
And at least one end 43a of the p-side contact layer 43 is exposed.

After forming the p-side ohmic electrode 52,
A mask (not shown) is removed, and, for example, the entire surface (that is,
End 43 of p-type clad layer 42 and p-side contact layer 43
A mask (not shown) made of silicon dioxide is selectively formed on the a and p side ohmic electrodes 52) by vapor deposition. Subsequently, as shown in FIG. 7B, the p-type cladding layer 42 and the p-type guide layer 4 are formed using this mask.
1, active layer 30, n-type guide layer 23, n-type cladding layer 2
2 and a part of the n-side contact layer 21 are sequentially etched by RIE or the like to expose the n-side contact layer 21 on the surface.

After exposing the n-side contact layer 21,
The mask (not shown) is removed, and the entire surface (that is, the n-side contact layer 21, the p-type cladding layer 42, the end portion 43a of the p-side contact layer 43, and the p-side ohmic electrode 52).
Then, a resist film (not shown) is formed, and a resist pattern (not shown) having openings corresponding to the formation positions of the n-side electrode 51 and the p-side Schottky electrode 53 is formed. After that, titanium, platinum, and gold, for example, are sequentially deposited on the entire surface (that is, on the resist film (not shown) and the region exposed by the opening), and the resist film (not shown) is removed together with each metal deposited thereon ( Lift off). Thereby, the n-side electrode 51 and the p-side Schottky electrode 53
To form.

After forming the n-side electrode and the p-side ohmic electrode 52, the substrate 1 is formed in the same manner as in the first embodiment.
1 is ground and cleaved to form a reflecting mirror film (not shown), which is further divided. As a result, a plurality of semiconductor lasers 60 shown in FIG. 5 are completed.

As described above, according to the present embodiment, the p-side contact layer 43 and the p-type cladding layer 42 are selectively removed into a band shape by using the metal film pattern 52a as a mask, and the metal film pattern is formed. Since at least one end of 52a in the cavity direction A is selectively removed to form the p-side ohmic electrode 52, the semiconductor laser 60 according to the present embodiment can be easily manufactured. The manufacturing process can be simplified and the manufacturing efficiency can be improved.

Although the present invention has been described with reference to the embodiments, the present invention is not limited to the above-mentioned embodiments, and various modifications can be made. For example, in the above embodiment, the n-side contact layer 21, the n-type cladding layer 22, the n-type guide layer 23, the active layer 30, the p-type guide layer 41, the p-type cladding layer 42 and the p-side contact layer 43 are formed. I have explained each semiconductor with specific examples,
Each of these layers may be made of another nitride semiconductor.

Further, in the above embodiment, the n-side contact layer 21, the n-type cladding layer 22, the n-type guide layer 23, the active layer 30, the p-type guide layer 41, the p-type cladding layer 42 and the p-side contact layer 43. I tried to stack them sequentially,
The present invention can be similarly applied to semiconductor lasers having other structures. For example, the n-type guide layer 23
The p-type guide layer 41 may not be provided, and a current blocking layer or the like may be provided between the active layer 30 and the p-type guide layer 41. Further, in the above-described embodiment, the current is narrowed by forming a part of the p-type cladding layer 42 and the p-side contact layer 43 into a thin strip shape, but the current may be narrowed by another structure. in addition,
In the above-described embodiment, the ridge waveguide type semiconductor laser in which the gain waveguide type and the refractive index waveguide type are combined has been described as an example. However, the gain waveguide type semiconductor laser and the refractive index waveguide type semiconductor laser are described. The same can be applied to a semiconductor laser.

Furthermore, in the above embodiment, the substrate 11
Was made of sapphire, gallium nitride, silicon carbide (SiC), spinel (MgAl
_It may be made of another material such as ₂ O ₄ ) or gallium arsenide (GaAs).

In addition, in the above embodiment, the n-type semiconductor layer 20, the active layer 30, and the p-type semiconductor layer 40 are MO.
Although the case of forming by the CVD method has been described, MB
It may be formed by another vapor phase growth method such as E method or hydride vapor phase growth method. Note that the hydride vapor phase growth method refers to a vapor phase growth method in which halogen contributes to transport or reaction.

Further, in the above embodiment, the n-side electrode 5
The constituent materials of the 1, p-side ohmic electrode 52 and the p-side Schottky electrode 53 have been described with specific examples, but may be composed of other materials.

[0052]

As described above, according to the semiconductor laser of any one of claims 1 to 3,
A p-side ohmic electrode that makes ohmic contact with the p-type semiconductor layer in the region other than at least one end in the cavity direction, and a p-side that makes Schottky contact with the p-type semiconductor layer in at least one end in the cavity direction. Since the Schottky electrode is provided, at least one end of the Schottky electrode can be a current non-injection region, the surface area of the p-side Schottky electrode can be increased, and the contact resistance with the wiring can be reduced. Therefore, it is possible to reduce the driving voltage and the power consumption while preventing the optical damage at the end portion, and to reduce the heat generation amount in the contact portion with the wiring. Further, the heat generated in the active layer can be efficiently released, and optical damage can be prevented more effectively. Therefore, high output can be easily achieved.

Further, any one of claim 4 and claim 6
According to the method of manufacturing a semiconductor laser as described in the item 1, a step of forming a p-side ohmic electrode in ohmic contact with the p-type semiconductor layer in a region other than at least one end portion in the cavity direction, and a method in the cavity direction. Since the step of forming a p-side Schottky electrode in Schottky contact with the p-type semiconductor layer at at least one end is included, the semiconductor laser of the present invention can be easily manufactured.

Particularly, according to the semiconductor laser manufacturing method of the fifth or sixth aspect, the n-side electrode and the p-side Schottky electrode are formed in the same step, or the p-type semiconductor is formed. Since the metal film pattern is used as a mask in the step of selectively removing a part of the layer and the p-side ohmic electrode is formed by selectively removing a part of the metal film pattern, the manufacturing process is simplified. And production efficiency can be improved.

[Brief description of drawings]

FIG. 1 is a perspective view showing a configuration of a semiconductor laser according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a manufacturing process of the semiconductor laser shown in FIG.

FIG. 3 is a cross-sectional view showing a manufacturing process following FIG.

FIG. 4 is a cross-sectional view showing a manufacturing process following FIG.

FIG. 5 is a perspective view showing a configuration of a semiconductor laser according to a second embodiment of the present invention.

FIG. 6 is a cross-sectional view showing a manufacturing process of the semiconductor laser shown in FIG.

FIG. 7 is a cross-sectional view showing a manufacturing process following FIG.

[Explanation of symbols]

10, 60 ... Semiconductor laser, 10a, 10b ... Resonator end face, 11 ... Substrate, 12 ... Insulating film, 20 ... N-type semiconductor layer,
21 ... N-side contact layer, 22 ... N-type cladding layer, 23
... n-type guide layer, 30 ... active layer, 40 ... p-type semiconductor layer,
41 ... P-type guide layer, 42 ... P-type clad layer, 43 ... P
Side contact layer, 43a ... End portion, 51 ... N-side electrode, 52
... p-side ohmic electrode, 52a ... metal film pattern, 53
… P-side Schottky electrode.

Continued front page    (72) Inventor Satoshi Hino             2 Soni at 53-53 Shirotori, Shiroishi City, Miyagi Prefecture             -In Shiraishi Semiconductor Co., Ltd. (72) Inventor Shiro Uchida             2 Soni at 53-53 Shirotori, Shiroishi City, Miyagi Prefecture             -In Shiraishi Semiconductor Co., Ltd. F-term (reference) 5F073 AA13 AA45 AA61 AA74 AA87                       CA07 CB05 CB22 DA05 DA25                       DA35 EA24

Claims (6)

[Claims] 1. A semiconductor laser comprising an n-type semiconductor layer, an active layer, and a p-type semiconductor layer each made of a nitride semiconductor, wherein the p-type semiconductor layer is formed in a region other than at least one end in the cavity direction. P in ohmic contact with the semiconductor layer
A semiconductor laser comprising a side ohmic electrode and a p-side Schottky electrode which is in Schottky contact with the p-type semiconductor layer at least at one end in the cavity direction. 2. The width of the end portion in the resonator direction is 5
The semiconductor laser according to claim 1, which is within 0 μm. 3. The semiconductor laser according to claim 1, wherein the p-side Schottky electrode is provided so as to cover the p-side ohmic electrode. 4. A method of manufacturing a semiconductor laser comprising an n-type semiconductor layer, an active layer and a p-type semiconductor layer, each of which is made of a nitride semiconductor, in a region other than at least one end in the cavity direction. including a step of forming a p-side ohmic electrode in ohmic contact with the p-type semiconductor layer, and a step of forming a p-side Schottky electrode in Schottky contact with the p-type semiconductor layer at least at one end in the cavity direction. A method for manufacturing a semiconductor laser, comprising: 5. The method further comprises the step of forming an n-side electrode in ohmic contact with the n-type semiconductor layer, and the n-side electrode and the p-side Schottky electrode are formed in the same step. Item 5. A method for manufacturing a semiconductor laser according to item 4. 6. A step of forming a metal film pattern on the p-type semiconductor layer and selectively removing a part of the p-type semiconductor layer using the metal film pattern as a mask, and the metal film pattern in the resonator direction. 5. A method of manufacturing a semiconductor laser according to claim 4, further comprising the step of selectively removing at least one end portion to form a p-side ohmic electrode.