JP2003198062A - Semiconductor laser device and method of manufacturing semiconductor laser device - Google Patents

Abstract

(57) Abstract: Provided are a semiconductor laser device having a structure excellent in reproducibility in device manufacturing and a method for manufacturing a semiconductor laser device. The semiconductor laser device has a structure in which an active layer extending along a crystal plane inclined with respect to a main surface of a substrate is sandwiched between a first conductivity type semiconductor layer and a second conductivity type semiconductor layer. The end surface substantially perpendicular to the crystal plane is set as the resonance surface, and the light emitting region is set as a partial region in the inclined surface of the active layer. Variation in emission wavelength can be suppressed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor laser device in which a semiconductor layer such as a compound semiconductor layer is selectively grown on a substrate and a method for manufacturing the semiconductor laser device.
In particular, the present invention relates to a semiconductor laser device formed by using a compound semiconductor layer such as a GaN-based semiconductor layer and a method for manufacturing the semiconductor laser device.

[0002]

2. Description of the Related Art As a method of manufacturing a semiconductor laser device,
A technique for forming a semiconductor laser device or a light emitting diode by selective growth in which a selective mask is formed on a sapphire substrate and a nitride semiconductor layer such as gallium nitride is grown from an opening formed in the selective mask is known. .
Generally, when growing gallium nitride, a sapphire substrate is often used. However, due to the lattice mismatch between the sapphire substrate and the gallium nitride to be grown, high-density dislocations may be present in the crystal. Therefore, the technique of forming the low temperature buffer layer on the substrate is one means for suppressing the defects generated in the crystal to be grown, and in order to reduce the crystal defects, Japanese Patent Laid-Open No. 10-312971 discloses that It combines selective lateral crystal growth (ELO: epitaxial lateral overgrowth). Further, as a method of forming a gallium nitride-based semiconductor laser, a technique of forming a laminated structure with an inclined surface by selective growth is also known, and such a technique is described in, for example, JP-A-11-31840. It

In addition, a light emitting diode of each color of blue, green and red and a semiconductor laser are combined to form each pixel, and each pixel is arranged in a matrix and driven independently to form an image display device. In addition, it is also possible to use as a white light emitting device or a lighting device by simultaneously emitting light from the light emitting elements of blue, green and red. In particular, a light emitting device using a nitride semiconductor has a band gap energy of about 1.9 eV to about 6.2 eV, and a full-color display is possible with one material. Therefore, research on a multicolor light emitting device is under way. . In the present specification, nitride means B, Al, Ga, In, Ta as I.
Group II refers to compounds containing N in Group V, 1% of the total
In some cases, it may include impurities of less than 1 × 10 ²⁰ cm ³ or less.

[0004]

First, in order to reduce threading dislocations from the substrate, in the technique of lateral selective crystal growth and the crystal growth method of forming a facet structure in the growth region, the threading from the substrate is The dislocations can be laterally bent by the facet structure portion or the like, and the crystal defects can be significantly reduced. However, after that, in order to form a light emitting region such as an active layer, selective crystal growth in the lateral direction is sufficiently performed or a facet structure is embedded, and the number of steps is increased, and the manufacturing process is increased. There is a problem that it takes a long time.

Further, in the gallium nitride based semiconductor laser and the manufacturing method thereof described in the above-mentioned Japanese Patent Laid-Open No. 11-31840, a conductive selection mask is formed substantially at the center of the opening of the insulating selection mask. A laminated structure having a triangular cross section that grows by selective growth is obtained. However, the laminated structure having a triangular cross section is mainly used only as a high resistance region for concentrating a current in the active layer at the center, and an S plane (1-101 plane) appears on the inclined surface. The S-plane itself is excellent in reproducibility of its production, but conversely, the region serving as the active layer is limited to the vicinity of the central conductive selection mask sandwiched by the laminated structure having a triangular cross section, and the important activity is required. It is difficult to control the film quality of the layers, which causes a problem that the reproducibility of the entire device deteriorates.

Further, for example, Japanese Patent Laid-Open No. 2000-183460.
In a semiconductor light emitting device using another inclined surface by selective growth, such as the semiconductor device described in Japanese Patent Publication, by making the surface forming the active layer an inclined surface, the active layer becomes non-parallel to the substrate, Therefore, it is supposed that the noise caused by the returning light can be reduced. However, in general, when an inclined surface formed by selective growth is used, the composition of crystals tends to be slightly deviated at a position close to the substrate and a position far from the substrate even within the same inclined plane. It is easy to make the emission wavelength longer. Therefore, in a device such as a semiconductor laser element that needs to have an emission wavelength within a predetermined range, excellent reproducibility in relation to the emission wavelength is required in the process.

In view of the above technical problems, it is an object of the present invention to provide a semiconductor laser device having a structure excellent in reproducibility in manufacturing the device and a method for manufacturing the semiconductor laser device.

[0008]

In a semiconductor laser device according to the present invention, an active layer extending along a crystal plane inclined with respect to a main surface of a substrate is composed of a first conductivity type semiconductor layer and a second conductivity type semiconductor layer. It is characterized in that it has a sandwiching structure, an end face that is substantially perpendicular to the crystal plane is a resonance plane, and a region that emits light is a partial region within the inclined plane of the active layer.

According to the semiconductor laser device of the present invention, the active layer extending along the crystal plane inclined with respect to the main surface of the substrate is sandwiched between the first conductive type semiconductor layer and the second conductive type semiconductor layer. By supplying a required current to the first conductive type semiconductor layer and the second conductive type semiconductor layer, light emission occurs in the active layer. Laser oscillation is possible because the end face of the active layer, which is substantially perpendicular to the crystal plane, is the resonance face, but the light emitting region in the active layer is limited to a partial region that is a part of the inclined plane. By doing so, it is possible to suppress variations in the emission wavelength.

Further, in the semiconductor laser device of the present invention, the active layer extending along the crystal plane inclined with respect to the main surface of the substrate is sandwiched between the first conductive type semiconductor layer and the second conductive type semiconductor layer,
The active layer, the first conductive type semiconductor layer, and the second conductive type semiconductor layer have a structure formed in a substantially triangular shape or a substantially trapezoidal shape in a cross section substantially perpendicular to the crystal plane, It is characterized in that the substantially vertical end surface is a resonance surface, and the light emitting region is a partial region in the inclined surface of the active layer.

Similar to the above-mentioned semiconductor laser device, it is possible to suppress variations in emission wavelength by limiting the light emitting region in the active layer to a partial region which is a part of the inclined surface. However, the active layer,
A semiconductor formed by selective growth by forming the first conductive type semiconductor layer and the second conductive type semiconductor layer into a substantially triangular shape or a substantially trapezoidal shape in a cross section substantially perpendicular to the crystal plane. The layer can be used as it is to form a partial region that emits light.

A method of manufacturing a semiconductor laser device according to the present invention comprises a step of forming a first conductivity type semiconductor layer having a crystal plane inclined with respect to a principal surface of a substrate on a substrate by selective growth, and the first conductivity type semiconductor. Forming an active layer on the layer, forming a second conductivity type semiconductor layer on the active layer, and forming a second conductivity type semiconductor on a part of an inclined surface on the second conductivity type semiconductor layer. Forming an electrode layer in contact with the layer.

By using the selective growth, it is possible to form a crystal plane inclined with respect to the principal surface of the substrate, and to form the active layer in the first layer.
By laminating on the conductive type semiconductor layer, an active layer having a crystal plane inclined with respect to the main surface of the substrate can be formed. After the second conductive type semiconductor layer is formed on the active layer, an electrode layer in contact with the second conductive type semiconductor layer is formed on a part of the inclined surface, so that the light emitting region of the active layer is inclined. The semiconductor laser device can be limited to a partial region, and variations in the emission wavelength of the semiconductor laser device can be suppressed, and a device having excellent reproducibility can be manufactured.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION The semiconductor laser device of the present invention comprises:
It has a structure in which an active layer extending along a crystal plane inclined with respect to a main surface of a substrate is sandwiched by a first conductive type semiconductor layer and a second conductive type semiconductor layer, and an end face substantially perpendicular to the crystal plane is a resonance plane. The light emitting region is a partial region in the inclined surface of the active layer.

Used in the semiconductor laser device according to the present invention
As a substrate to be used, a wurtzite type compound semiconductor layer is formed.
There is no particular limitation as long as it can be achieved, and various kinds can be used.
Can be used. For example, it can be used as a substrate
Sapphire (Al_TwoO _Three, Surface A, surface R, surface C
Mu. ), SiC (including 6H, 4H, and 3C), Ga
N, Si, ZnS, ZnO, AlN, LiMgO, Li
GaO_Two, GaAs, MgAl_TwoO_Four, InAlGaN
And the like, and preferably these materials
Is a hexagonal substrate or a cubic substrate, and more
A hexagonal crystal substrate is preferred. For example, the sapphire group
When using a plate, gallium nitride (GaN) -based compound
C, which is widely used when growing semiconductor materials
A sapphire substrate whose main surface is a surface can be used.
In this case, the C plane as the main surface of the substrate is in the range of 5 to 6 degrees.
It includes the plane orientation tilted at. For manufacturing semiconductor devices
It is also possible to use widely used silicon substrates etc.
It is possible. The substrate itself supports the semiconductor thin film being manufactured.
It is used for various purposes and is peeled off when the device is completed.
A laser that can be used as a device structure and has a completed substrate
The element structure used for the element may be used.

The lower layer of the selective mask for selective growth may be the substrate itself, but an undergrown layer such as a buffer layer may be included to obtain good crystallinity at the time of selection. A compound semiconductor layer can be selected as the underlying growth layer, and a wurtzite type compound semiconductor is preferably selected because a facet structure is formed in a later step. Further, as the compound semiconductor layer, BeMgZnCd, which is a nitride semiconductor having a wurtzite crystal structure, is used.
S-based compound semiconductors and BeMgZnCdO-based compound semiconductors are preferable. As the crystal layer made of a nitride semiconductor, for example, a Group III-based compound semiconductor can be used, and a gallium nitride (GaN) -based compound semiconductor,
Aluminum nitride (AlN) -based compound semiconductors, indium nitride (InN) -based compound semiconductors, indium gallium nitride (InGaN) -based compound semiconductors, and aluminum gallium nitride (AlGaN) -based compound semiconductors can be preferably formed, and in particular gallium nitride-based Compound semiconductors are preferred. As an example, an undoped GaN layer may be formed on a sapphire substrate, and then a Si-doped GaN layer may be formed. In the present invention, InGa
N, AlGaN, GaN, etc. do not necessarily mean nitride semiconductors of only ternary mixed crystals and only binary mixed crystals. For example, in InGaN, a trace amount of Al and other impurities within a range that does not change the action of InGaN. Needless to say, the scope of the present invention includes the above. Further, the surface substantially equivalent to the S-plane includes a plane orientation tilted in the range of 5 to 6 degrees with respect to the S-plane. Here, in the present specification,
A nitride refers to a compound in which B, Al, Ga, In, and Ta are group III and N is included in group V, and may include impurities within 1% or 1 × 10 ²⁰ cm ³ or less of the whole.

As a method of growing this compound semiconductor layer,
Various vapor phase epitaxy methods can be mentioned, for example, vapor phase epitaxy methods such as organometallic compound vapor phase epitaxy method (MOCVD (MOVPE) method) and molecular beam epitaxy method (MBE method),
A hydride vapor phase epitaxy method (HVPE method) can be used. Among them, according to the MOVPE method, a material having good crystallinity can be obtained quickly. In the MOVPE method, TMG (trimethylgallium) and TEG (triethylgallium) as Ga sources, TMA (trimethylaluminum) and TEA (triethylaluminum) as Al sources, and TMI (trimethylindium) and TEI (triethylindium) as In sources. ) And other alkyl metal compounds are often used, and as the nitrogen source, gases such as ammonia and hydrazine are used. As the impurity source, silane gas is used for Si, germane gas is used for Ge, Cp2Mg (cyclopentadienyl magnesium) is used for Mg, and DEZ (diethyl zinc) is used for Zn. In the MOVPE method, these gases are supplied to the surface of the substrate heated to, for example, 600 ° C. or higher to decompose the gas, thereby
The nAlGaN-based compound semiconductor can be epitaxially grown.

In the semiconductor laser device of the present invention,
On the surface of the compound semiconductor layer to be the underlying growth layer for crystal growth, for example, a selection mask having an opening opening in a stripe shape is formed, and a ridge line parallel to the long side of the opening opening in a stripe shape is formed. Then, a semiconductor layer is formed by selective growth. The mask is a growth inhibiting film formed directly on the main surface of the substrate or on a buffer layer or other layers formed on the substrate. For example, a mask material made of an insulating film such as a silicon oxide film or a silicon nitride film is used. It The shape of the opening of this mask is a stripe shape as an example, but it may be another shape capable of obtaining a resonance surface, for example, a curved shape, a circular shape, an elliptical shape, a triangular shape, a pentagonal shape. Alternatively, it may be a polygonal shape such as a hexagonal shape, or a composite thereof. Moreover, it is possible to form a plurality of openings as in a normal semiconductor process.

After forming such a mask for selective growth, a semiconductor layer is formed by selective crystal growth. As an example, the semiconductor layer is formed so as to have a ridge parallel to the long side of the opening which is opened in a stripe shape. This semiconductor layer is formed in a substantially triangular shape in a cross section substantially perpendicular to an inclined surface described later. When the conditions for selective growth are changed, the cross section is formed into a substantially trapezoidal shape.

Crystal growth in this selective growth can be performed by the same method as the method for forming the compound semiconductor layer described above. Specific examples of the growth method include various vapor phase growth methods, for example, a vapor phase growth method such as a metal organic compound vapor phase growth method (MOCVD (MOVPE) method) and a molecular beam epitaxy method (MBE method). A growth method or a hydride vapor phase epitaxy method (HVPE method) can be used.
In the MOVPE method, TMG (trimethylgallium) and TEG (triethylgallium) are used as Ga sources, and TMA (trimethylaluminum) and TE are used as Al sources.
As A (triethylaluminum) and In source,
Alkyl metal compounds such as TMI (trimethylindium) and TEI (triethylindium) are often used, and gases such as ammonia and hydrazine are used as nitrogen sources. As the impurity source, Si is silane gas, Ge is germane gas, Mg is Cp2Mg (cyclopentadienyl magnesium),
The same applies to the case where a gas such as DEZ (diethyl zinc) is used for Zn.

In the semiconductor laser device according to the present invention, in order to form a crystal plane inclined with respect to the main surface of the substrate, the semiconductor is formed by selective growth so as to have a ridge line parallel to the long side of the stripe-shaped opening. A layer is formed.
The pair of crystal planes of the semiconductor layer that sandwich the ridgeline are preferably planes selected from {1-101} planes or {11-22} planes or planes substantially equivalent to each of these planes. desirable. The pair of crystal planes are crystal planes that are inclined with the ridge line in between. For example, by setting the main surface of the substrate or the substrate to be the C + plane, the S plane or a plane substantially equivalent to the S plane, or {11- 22} plane or {11-2
It is possible to easily form a surface substantially equivalent to the 2} surface. In the case where the selective growth is performed, the S-plane and the {11-22} plane are C-planes which are inclined planes inclined with respect to the main surface of the substrate.
It is a stable surface that can be seen when selectively growing on the + surface, and is a surface that is relatively easy to obtain. Similar to the C + plane and the C- plane existing in the C plane, the S + plane includes the S + plane and the S- plane, but in the present specification, unless otherwise specified, C + plane is present.
The S + plane is grown on the plane GaN, and this is described as the S plane. Regarding the S surface, the S + surface is the stable surface. The surface index of the C + surface is (0001).

Regarding the S-plane, when a crystal layer is formed using a gallium nitride-based compound semiconductor, the number of bonds from Ga to N is 2 or 3 on the S-plane, which is the second largest after the C-plane. Here, since the C-plane cannot be practically obtained on the C + plane, the number of bonds on the S-plane becomes the largest.
For example, when a nitride is grown on a sapphire substrate having a C + plane as the main surface, the surface of the wurtzite type nitride is generally C
Although it becomes the + plane, the S plane can be stably formed by utilizing selective growth, and the N bond, which tends to be easily detached on the plane parallel to the C + plane, is bonded from Ga by one bond. On the other hand, on the inclined S-plane, at least one pound is used for joining. Therefore, V /
The III ratio is increased, which is advantageous for improving the crystallinity of the laminated structure. Further, when grown in a direction different from that of the substrate, dislocations extending upward from the substrate may be bent, which is also advantageous in reducing defects.

The longitudinal direction of the stripe-shaped opening of the selective growth mask is [11-20] direction or [1-100].
In the case of the direction, the semiconductor layer can be easily formed to have a ridge line parallel to the longitudinal direction of the opening. In addition, an opening formed in a stripe shape having a longitudinal direction that is inclined at an angle of 0.2 degrees or more and 20 degrees or less from either the [11-20] direction or the [1-100] direction is used for selective growth. It can also be used on the occasion. In this way, when the direction is tilted by the required angle, the crystal steps tend to be aligned over the entire surface of a certain crystal, and electrodes are formed in the portions where the crystal steps are aligned, so that The variation can be greatly reduced. If the direction in which the longitudinal direction of the opening is displaced from either the [11-20] direction or the [1-100] direction is less than 0.2 degrees, there is almost no displacement in the [11-20] direction. Alternatively, they only show the same tendency of crystallinity as the [1-100] direction itself. Further, when an opening having a longitudinal direction inclined by an angle of more than 20 degrees is used, the influence of other crystal steps may be exposed to the crystal plane.

In such a semiconductor layer, a first conductivity type semiconductor layer, an active layer, and a second conductivity type semiconductor layer are laminated on inclined surfaces formed on both sides of the ridge. The first conductivity type semiconductor layer may be continuously formed with the lower semiconductor layer. In the first conductive type semiconductor layer, the active layer, and the second conductive type semiconductor layer stacked on the inclined surface, the first conductive type is p type or n type, and the second conductive type is the opposite conductive type. is there. For example, in the case where the crystal layer forming the S-plane is composed of a silicon-doped gallium nitride-based compound semiconductor layer, the n-type semiconductor layer is composed of a silicon-doped gallium-nitride-based compound semiconductor layer, and an InGaN layer is formed thereon as an active layer. Then, a magnesium-doped gallium nitride-based compound semiconductor layer is further formed thereon as a p-type semiconductor layer to form a double hetero structure. A structure in which an InGaN layer, which is an active layer, is sandwiched between AlGaN layers or only one side is
It is also possible to adopt a structure in which an lGaN layer is formed. The active layer may be composed of a single bulk active layer, but a quantum well having a single quantum well (SQW) structure, a double quantum well (DQW) structure, a multiple quantum well (MQW) structure, or the like. The structure may be formed. A barrier layer is additionally used in the quantum well structure for the purpose of separating the quantum well. When the active layer is an InGaN layer, the structure is particularly easy to manufacture in the manufacturing process, and the light emitting characteristics of the device can be improved. Furthermore, this InGaN layer is particularly easy to crystallize and has good crystallinity when grown on the S-plane, which has a structure in which nitrogen atoms are hard to be desorbed, and the luminous efficiency can be improved. Note that a nitride semiconductor has a property of becoming n-type even if it is not doped due to nitrogen vacancies formed in the crystal. However, by doping donor impurities such as Si, Ge, and Se during crystal growth, It can be a preferred n-type. In order to make the nitride semiconductor p-type, Mg, Zn, C, Be, Ca, B in the crystal
Although it can be obtained by doping an acceptor impurity such as a, in order to obtain a p-layer having a high carrier concentration, after doping the acceptor impurity, annealing is performed at 400 ° C. or higher in an inert gas atmosphere such as nitrogen or argon. However, there is also a method of activation by electron beam irradiation or the like, and a method of activation by microwave irradiation, light irradiation or the like.

The first conductive type semiconductor layer, the active layer, and the second conductive type semiconductor layer extend in a plane parallel to the inclined surface, and are formed in the plane parallel to the inclined surface. Can be easily performed if the crystal is continuously grown where the inclined surface is formed. The first conductivity type clad layer can be made of the same material and have the same conductivity type as the crystal layer forming the S-plane, and it should be formed while continuously adjusting the concentration after forming the crystal layer forming the S-plane. Alternatively, as another example, a structure in which a part of the crystal layer of the S-plane functions as the first conductivity type semiconductor layer may be used.

First conductivity type semiconductor layer and second layer sandwiching the active layer
An electrode is directly or indirectly connected to the conductive type semiconductor layer. In the semiconductor laser device according to the present invention, the light emitting region is set to a partial region within the inclined surface of the active layer. The partial area does not mean that it is formed over the entire area in the in-plane direction of the inclined surface, but indicates an area that is formed only in a partial area. Such a partial region may be formed at one location in the direction of the inclined surface, or may be formed at a plurality of locations in the direction of the inclined surface. Part of the region is a region that substantially contributes to light emission, and it is possible to narrow the current by forming electrodes narrowly or to concentrate the current by using an insulating film as described below. .

The width in the in-plane direction of such a partial region is
The variation of the emission wavelength of the semiconductor laser device is about 10
It is desirable to set it within the range of nm or less. In this way, the variation of the emission wavelength of the semiconductor laser device is about 10 nm.
The reason for setting the width in the following range is that the half value width is 20 nm according to the experimental data conducted by the present inventors.
There is a fact that the active layer having a spectrum within the range is likely to oscillate, and in that case, the peak wavelength width in which the peak wavelength is allowed in the electrode stripe is the half-value width as a degree.
This is because it can be inferred that it is within 0 nm.

According to an empirical rule, such setting of the width is as follows.
In the gallium nitride-based compound semiconductor layer, the partial region has a width of about 3 μm or less in the in-plane direction, preferably 2 μm or less, and more preferably 1 μm or less. That is, the range that can have the above-mentioned wavelength distribution of 10 nm is shown in FIG. 14 from the relationship between the height from the bottom of a typical pyramid and the emission peak wavelength according to the experiment conducted by the present inventors. Be done. FIG. 14 is a characteristic diagram in which the horizontal axis represents the length from the bottom (μm) and the vertical axis represents the peak wavelength (nm). The length from the bottom is the length along the slope and corresponds to the height. According to FIG. 14, if the peak shift is about 10 nm, the height width is about 3 μm at a position where the length from the bottom is relatively long, that is, at a position apart from the bottom to some extent. The result is that the variation in the emission wavelength of the laser element is reduced.

As a structure of a partial region, it is possible to form an electrode for supplying a current to the active layer so as to have a predetermined width in the direction of the inclined surface, or a semiconductor of the first conductivity type sandwiching the active layer. It is also possible to form at least one of the layer and the second conductivity type semiconductor layer so as to have a predetermined width in the direction of the inclined plane, or to form the active layer so as to have a predetermined width in the direction of the inclined plane. Is. As a method of narrowing the width of the electrode for supplying a current to the active layer, it is possible to narrow the width of the electrode layer or the first and second conductivity type semiconductor layers by photolithography. In order to effectively narrow the width, an insulating film may be formed in a stripe-shaped opening for narrowing the current.

Here, each electrode is formed for each element, but one of the p-electrode and the n-electrode can be shared between a plurality of laser elements. In order to reduce the contact resistance, a required contact layer may be formed and then an electrode may be formed on the contact layer. Generally, each electrode is formed by depositing a multi-layered metal film by vapor deposition or the like, but it can be finely processed by lift-off or the like using photolithography in order to divide each element. Each electrode may be formed on one surface of the selective crystal growth layer or the substrate, or electrodes may be formed on both sides to wire the electrodes at a higher density. Further, the electrodes that are independently driven may be formed by finely processing the same material, but it is also possible to use electrode materials of different materials for each region.

In the semiconductor laser device of the present invention, a resonator is formed on the end face of the stripe-shaped crystal growth portion or the like. As is well known, a resonator can be formed by cleaving a crystal, and for example, a resonator plane can be formed by cleaving a plane substantially perpendicular to the longitudinal direction of a striped opening. it can. Even if the resonance surface is not formed by cleavage, the resonance surface may be formed by an etching method or the like.

A display device can be constructed by forming a plurality of semiconductor laser elements of the present invention so as to be arranged. In a display device in which a plurality of such semiconductor laser elements are arranged, the light emitting elements can be arranged at a high density, and the easiness of manufacturing can be improved by sharing the electrodes. Further, it is not limited to a display device that emits light of a single color, and a display device that emits light of multiple colors can be configured.

The present invention will be described in more detail below with reference to each embodiment. The semiconductor laser device of the present invention can be modified and changed without departing from the spirit of the invention, and the present invention is not limited to the following embodiments.

[First Embodiment] FIG. 1 is a cross-sectional view of essential parts of a gallium nitride-based compound semiconductor laser device of the present embodiment. A selective mask 12 made of, for example, a silicon oxide film is formed on a substrate 11 whose main surface is a laminated body of a sapphire substrate and a base growth layer. Specifically, the base 11 is a structure in which, for example, an undoped GaN layer and a silicon-doped GaN layer are stacked on a sapphire substrate whose main surface is the C surface. An AlN layer or the like may be formed as the buffer layer. An opening 13 having a stripe shape is formed in the selection mask 12 by hydrofluoric acid-based etching after forming a resist mask. In this embodiment, the opening 1
In order to achieve crystal growth with ridges in the longitudinal direction of 3 [1
-100] direction or [11-20] direction.

From the elongated strip-shaped opening 13, silicon-doped Ga is used as a first conductivity type semiconductor layer by selective growth.
The N layer 14 is formed. In this embodiment, the silicon-doped GaN layer 14 has a substantially triangular cross section, and since it grows from the elongated strip-shaped opening 13, the direction perpendicular to the illustrated cross section is the longitudinal direction. Resonance planes are formed by cleavage or etching at both ends (not shown) in the longitudinal direction, and laser oscillation becomes possible. Silicon-doped G
In the aN layer 14, the plane formed by the hypotenuse having a substantially triangular cross section serves as a crystal plane inclined with respect to the main surface of the substrate. During the growth of the silicon-doped GaN layer 14, its growth temperature is set to 980 ° C., for example.

On the silicon-doped GaN layer 14, I
n _0.05 Ga _0.95 N layer 15 is formed, for example, a thickness of 10nm as a guide layer, its _{an In 0.05} Ga
In _0.2 Ga as an active layer is formed on the _0.95 N layer 15.
_{The 0.8} N layer 16 is formed to have a film thickness of, for example, 3 nm.
On the n _0.2 Ga _0.8 N layer 16 as a guide layer, In
_{0. The 05} Ga _0.95 N layer 17 is formed with a film thickness of 10 nm, for example. These In _{0. 05} Ga _0.95 N layer 1
5, In _0.2 Ga _0.8 N layer 16, and In _0.05
The Ga _0.95 N layer 17 is formed so as to be stacked on the inclined surfaces on both sides across the ridge line of the silicon-doped GaN layer 14 corresponding to the apex of the substantially triangular cross section.

In _0.05 Ga as a guide layer
_A magnesium-doped GaN layer 18 is formed as a second conductivity type semiconductor layer on the _0.95 N layer 17. The magnesium-doped GaN layer 18 is a layer functioning as a second conductivity type semiconductor layer and is a p-type compound semiconductor layer.
An insulating film 21 such as a silicon oxide film is formed on the magnesium-doped GaN layer 18. This insulating film 21
Is formed so as to cover the semiconductor layer having a triangular cross section,
An opening 20 is formed by opening a part of the insulating film 21 on the inclined surface.
Is formed. The opening 20 is extended in the horizontal direction and faces the semiconductor layer at the height where the opening 20 exists. The width on the slope of the opening 20 is, for example, 1 to 3 μm.
It is set as thin as about m.

A p-side electrode layer 19 is formed in the region where the opening 20 is formed. The p-side electrode layer 19 is, for example, Ni / P
It has a laminated structure of t / Au or Ni (Pd) / Pt / Au. After the p-side electrode layer 19 is formed on the entire surface, it is formed into a thin strip-shaped pattern by a method such as etching or lift-off. P partially formed on this inclined surface
The side electrode layer 19 is deposited on the interface of the magnesium-doped GaN layer 18 through the opening 20 that is thinly opened to, for example, about 1 to 3 μm as described above, and has a predetermined height of the semiconductor layer having a triangular cross section. An electric current is concentratedly supplied to the portion to make the region to emit light a partial region limited in the width direction of the slope.

Next to the semiconductor layer having a triangular cross section, the n-side electrode layer 22 is formed by opening the selection mask 12 and the insulating film 21. The n-side electrode layer 22 is made of, for example, Ti / Al / P.
It has a t / Au electrode structure and is electrically connected to the silicon-doped GaN layer 14, which is the first conductivity type semiconductor layer, via the substrate 11.

FIG. 2 is a schematic view conceptually showing a partial region in the semiconductor laser device of this embodiment. A semiconductor layer 28 having a triangular prism shape is arranged so that the horizontal direction is the longitudinal direction, and both end faces 25, 25 rising vertically serve as the laser resonance plane. A partial region 27 serving as a light emitting region is formed in the middle of the inclined surface 26 in the height direction. That is, in the semiconductor laser device according to the present embodiment, the partial region 27 is provided over the partial width W ₁ instead of the entire region width R of the inclined surface 26.
Is formed. Therefore, the light generated in the partial area 27 is
The variation in wavelength is suppressed, and a laser element having a narrow half width and excellent reproducibility can be obtained when resonating on the resonance surface. The width R of the entire area of the inclined surface 26 is within a range of, for example, about 5 μm to 50 μm.

Here, a method of manufacturing the semiconductor laser device according to the present embodiment will be described with reference to FIGS. First, as shown in FIG. 3, a selective mask 32 made of a silicon oxide film is formed on a substrate 31 which is a laminated body of a sapphire substrate and a base growth layer. The base 31 is
For example, on a sapphire substrate whose main surface is the C surface,
For example, undoped GaN layer and silicon-doped GaN
It is a structure in which layers are laminated. The selection mask 32 has openings 33 formed in stripes with the horizontal direction as the longitudinal direction.
Is formed. This horizontal direction is, for example, the [1-100] direction or the [11-20] direction.

Next, as shown in FIGS. 4 and 5, a silicon-doped GaN layer 34 functioning as a first conductivity type semiconductor layer is formed by selective growth in which an elongated strip-shaped opening 33 is formed in the selection mask 32. It FIG. 5 corresponds to the cross-sectional view taken along the line VV of FIG. 4 and is a process cross-sectional view of the same process.
By this selective growth, a silicon-doped GaN layer 34 having a substantially triangular cross section is formed. The inclined surfaces formed on both sides of the ridge of the GaN layer 34 are, for example, S-plane or {11-
22} plane, which is a crystal plane that is stably formed during selective growth.

Silicon-doped GaN having a substantially triangular cross section
After forming the layer 34, as shown in FIG.
The n _0.05 Ga _0.95 N layer 35 has a film thickness of 10 nm, for example.
In is formed, the on _In 0.05 _{Ga 0.95} N layer 35 is formed by the _In 0.2 _{Ga 0.8} N layer 36 as an active layer thickness, for example 3 nm, the _In 0.2 _{Ga 0. 8} N
On _0.05 Ga _0.95 as a guide layer on the layer 36
The N layer 37 is formed to have a film thickness of 10 nm, for example. A magnesium-doped GaN layer 38 is formed as a second conductivity type semiconductor layer on the In _0.05 Ga _0.95 N layer 37 as a guide layer. These In _0.05 Ga _0.95
N layer 35, In _0.2 Ga _0.8 N layer 36, In
_{Since the 0.05} Ga _0.95 N layer 37 and the magnesium-doped GaN layer 38 are thin films and are laminated, they reflect inclined surfaces such as the S-plane of the magnesium-doped GaN layer 38, and both sides of the ridge line are reflected. Is formed by forming inclined surfaces, respectively.

After stacking these semiconductor layers, as shown in FIG. 7, the entire surface is covered with an insulating film 39 such as a silicon oxide film or a silicon nitride film. The insulating film 39 is finely processed by photolithography or the like so as to open a part of the slope, and the opening 40 is formed by the fine processing. At the bottom of the opening 40, the surface of the magnesium-doped GaN layer 38 is exposed in stripes.
The width of the opening 40 is about 3 μm or less, preferably 2 μm or less, more preferably 1 μm.
It is set to the following width.

Next, as shown in FIG. 8, the p-side electrode layer 41 is formed.
Are formed in the region where the opening 40 is formed. The p-side electrode layer 41 is made of, for example, Ni / Pt / Au or Ni (Pd) /
It has a laminated structure of Pt / Au. Although not shown in the drawings, an n-side electrode layer is formed below, and a cleavage plane or the like is used to form a resonance plane on an end face substantially perpendicular to the crystal plane. The steps of forming the n-side electrode layer and the resonance surface may be repeated. By flowing a required current, a current is supplied from the p-side electrode layer 41 formed in a stripe shape, and light emission occurs only in a narrow region of the crystal plane that is tilted to reflect the p-side electrode layer 41.

In such a manufacturing method, since the narrow opening 40 formed in the insulating film 39 functions as a current constriction portion, it is possible to form a laser element while suppressing variations in emission wavelength. It is possible to manufacture a semiconductor laser device having a stable emission wavelength with good reproducibility.

In the present embodiment, the opening 40 is formed by photolithography in order to form a partial region for limiting the light emission region in the direction of the inclined plane.
Although the p-side electrode layer 41 is described as being formed with a narrow width, the thickness of the insulating film 39 is increased to form an opening having a high aspect ratio, and the p-side electrode layer is lifted off due to a step in the opening. It is also possible to form 41 with a narrow width. Further, in the present embodiment, the electrode is described as being continuous in the horizontal direction, but it may have a structure in which the electrode or the active layer is intermittently present in the horizontal direction.

[Second Embodiment] FIG. 9 is a sectional view showing the device structure of a semiconductor laser device according to the second embodiment. The present embodiment is an example in which two p-side electrode layers are formed in the inclined surface, and has an element structure capable of controlling a plurality of emission wavelengths.

A selective mask 52 made of, for example, a silicon oxide film is formed on a base body 51, which is a laminated body of a sapphire substrate and a base growth layer, whose main surface is a substrate. Specifically, the base 51 is a structure in which, for example, an undoped GaN layer and a silicon-doped GaN layer are stacked on a sapphire substrate whose main surface is the C surface. An AlN layer or the like may be formed as the buffer layer. In the selection mask 52, a striped opening 53 is formed by hydrofluoric acid etching after forming a resist mask. Also in this embodiment,
Similar to the above-described embodiment, the longitudinal direction of the opening 53 is the [1-100] direction or the [11-20] direction in order to obtain the crystal growth having the ridge.

From the elongated strip-shaped opening 53, silicon-doped Ga is used as a first conductivity type semiconductor layer by selective growth.
The N layer 54 is formed. In this embodiment, as in the above-described embodiments, the silicon-doped GaN layer 54 has a substantially triangular cross section, and in order to grow from the elongated strip-shaped opening 53, the direction perpendicular to the illustrated cross section is the longitudinal direction. To do.
Resonance planes are formed by cleavage or etching at both ends (not shown) in the longitudinal direction, and laser oscillation becomes possible. In the silicon-doped GaN layer 54, the plane formed by the hypotenuse having a substantially triangular cross section serves as a crystal plane inclined with respect to the main surface of the substrate. Silicon-doped GaN layer 54
The growth temperature is set to 980 ° C., for example.

On the silicon-doped GaN layer 54, I
n _0.05 Ga _0.95 N layer 55 is formed, for example, a thickness of 10nm as a guide layer, its _{an In 0.05} Ga
In _0.2 Ga as an active layer is formed on the _0.95 N layer 55.
_{The 0.8} N layer 56 is formed to have a film thickness of, for example, 3 nm.
On the n _0.2 Ga _0.8 N layer 56 as a guide layer In
_{0. The 05} Ga _0.95 N layer 57 is formed to have a film thickness of 10 nm, for example. These In _{0. 05} Ga _0.95 N layer 5
5, In _0.2 Ga _0.8 N layer 56, and In _0.05
The Ga _0.95 N layer 57 is formed so as to be laminated on the inclined surfaces on both sides across the ridge of the silicon-doped GaN layer 54 corresponding to the apex of the substantially triangular cross section.

In _0.05 Ga as a guide layer
_A magnesium-doped GaN layer 58 is formed on the _0.95 N layer 57 as a second conductivity type semiconductor layer. The magnesium-doped GaN layer 58 is a layer functioning as a second conductivity type semiconductor layer and is a p-type compound semiconductor layer.
An insulating film 61 such as a silicon oxide film is formed on the magnesium-doped GaN layer 58. This insulating film 61
Is formed so as to cover the semiconductor layer having a triangular cross section. Openings 66 and 67 are formed by opening two locations on the inclined surface of the insulating film 61. The openings 66 and 67 are extended in the horizontal direction, respectively, and the semiconductor layer is exposed at the openings 66 and 67. The width of the openings 66, 67 on the slope is set to be thin, for example, about 1 to 3 μm.

P-side electrode layers 64 and 65 are formed in the regions where the openings 66 and 67 are formed. p-side electrode layers 64, 65
Is, for example, Ni / Pt / Au or Ni (Pd) / Pt /
It has a laminated structure of Au. These p-side electrode layers 64, 65
After being formed on the entire surface, it is formed into a thin strip-shaped pattern by a technique such as etching or lift-off. The p-side electrode layers 64 and 65 partially formed on the inclined surface have the openings 6 that are thinly opened to, for example, about 1 to 3 μm as described above.
6 and 67 are applied to the interface of the magnesium-doped GaN layer 58, and a current is concentratedly supplied to a predetermined height portion of the semiconductor layer having a triangular cross section, and the region to emit light is formed in the width direction of the slope. The partial areas 68 and 69 are defined by. p
The side electrode layers 64 and 65 can be formed by patterning films having the same laminated structure by a photolithography technique, and electrode layers having different structures and materials may be sequentially formed and finely processed.

An n-side electrode layer 62 is formed in the opening 63 that opens the selection mask 52 and the insulating film 61 beside the semiconductor layer having a triangular cross section. The n-side electrode layer 62 has, for example, a Ti / Al / Pt / Au electrode structure, and the base 51 is formed on the silicon-doped GaN layer 54 that is the first conductivity type semiconductor layer.
Electrically connected via.

In the semiconductor laser device of this embodiment having the structure shown in FIG. 9, two electrode layers 64 and 65 are formed in the crystal plane inclined with respect to the principal surface of the substrate, and generally in the inclined plane. Is shifted to the longer wavelength side as the emission wavelength is closer to the apex, so that the emission wavelength is different between the partial region 68 corresponding to the p-side electrode layer 64 and the partial region 69 corresponding to the p-side electrode layer 65. Light emission of two wavelengths is possible within the same device. In addition, since the narrow openings 66 and 67 formed in the insulating film 61 function as current confinement portions, it is possible to form the laser element while suppressing variations in the emission wavelength, and stabilize the emission wavelength. A semiconductor laser device can be manufactured with good reproducibility.

[Third Embodiment] FIG. 10 is a sectional view showing the device structure of a semiconductor laser device according to the third embodiment. The present embodiment is an example in which a p-side electrode layer is formed on each of two inclined surfaces facing each other with a ridge line in between.

A selective mask 72 made of, for example, a silicon oxide film is formed on a base body 71, which is a laminated body of a sapphire substrate and an underlying growth layer, whose main surface is a substrate. The base 71 is a structure in which, for example, an undoped GaN layer and a silicon-doped GaN layer are stacked on a sapphire substrate whose main surface is the C surface. An AlN layer or the like may be formed as the buffer layer. An opening 73 having a stripe shape is formed in the selection mask 72 by hydrofluoric acid etching after forming a resist mask. Also in the present embodiment, the longitudinal direction of the opening 73 is, for example, the [1-100] direction or the [11-20] direction in order to obtain the crystal growth having the ridge line, as in the above-described embodiments.

From the elongated strip-shaped opening 73, silicon-doped Ga is used as a first conductivity type semiconductor layer by selective growth.
The N layer 74 is formed. In this embodiment as well, as in the above-described embodiments, the silicon-doped GaN layer 74 has a substantially triangular cross section and grows from the elongated strip-shaped opening 73. Therefore, the direction perpendicular to the illustrated cross section is the longitudinal direction. To do. Resonance planes are formed by cleavage or etching at both ends (not shown) in the longitudinal direction, and laser oscillation becomes possible. In the silicon-doped GaN layer 74, the plane formed by the hypotenuse having a substantially triangular cross section serves as a crystal plane inclined with respect to the main surface of the substrate. During the growth of the silicon-doped GaN layer 74, its growth temperature is set to 980 ° C., for example.

On the silicon-doped GaN layer 74, I
n _0.05 Ga _0.95 N layer 75 is formed, for example, a thickness of 10nm as a guide layer, its _{an In 0.05} Ga
In _0.2 Ga as an active layer is formed on the _0.95 N layer 75.
_{The 0.8} N layer 76 is formed to have a film thickness of, for example, 3 nm.
On the n _0.2 Ga _0.8 N layer 76 as a guide layer In
_{0. The 05} Ga _0.95 N layer 77 is formed with a film thickness of 10 nm, for example. These In _{0. 05} Ga _0.95 N layer 7
5, In _0.2 Ga _0.8 N layer 76, and In _0.05
The Ga _0.95 N layer 77 is formed so as to be stacked on the inclined surfaces on both sides across the ridge of the silicon-doped GaN layer 74 corresponding to the apex of the substantially triangular cross section.

In _0.05 Ga as a guide layer
_A magnesium-doped GaN layer 78 is formed as a second conductivity type semiconductor layer on the _0.95 N layer 77. The magnesium-doped GaN layer 78 functions as a second conductivity type semiconductor layer and is a p-type compound semiconductor layer.
An insulating film 81 such as a silicon oxide film is formed on the magnesium-doped GaN layer 78. This insulating film 81
Is formed so as to cover the semiconductor layer having a triangular cross section.

A part of the insulating film 81 on the inclined surface is opened, and openings 86 and 87 are formed on both opposed inclined surfaces.
These openings 86 and 87 are extended horizontally,
The semiconductor layer at the height where the openings 86 and 87 exist is exposed. The width on the slope of the openings 86, 87 is, for example, 1
The thickness is set to about 3 μm.

P-side electrode layers 84 and 85 are formed in the regions where the openings 86 and 87 are formed. p-side electrode layers 84, 85
Is, for example, Ni / Pt / Au or Ni (Pd) / Pt /
It has a laminated structure of Au. These p-side electrode layers 84, 85
After being formed on the entire surface, it is formed into a thin strip-shaped pattern by a technique such as etching or lift-off. The p-side electrode layers 84 and 85 partially formed on the inclined surface have the openings 8 that are thinly opened to, for example, about 1 to 3 μm as described above.
6 and 87 are applied to the interface of the magnesium-doped GaN layer 78, and the current is concentratedly supplied to a predetermined height portion of the semiconductor layer having a triangular cross section, and the region to emit light is formed in the width direction of the slope. The partial regions 89 and 88 are defined by. p
The side electrode layers 84 and 85 can be formed by patterning films having the same laminated structure by a photolithography technique, and electrode layers having different structures and materials may be sequentially formed and finely processed.

Next to the semiconductor layer having a triangular cross section, an n-side electrode layer 82 is formed in an opening 83 that opens the selection mask 72 and the insulating film 81. The n-side electrode layer 82 has, for example, a Ti / Al / Pt / Au electrode structure, and the base 71 is formed on the silicon-doped GaN layer 74 which is the first conductivity type semiconductor layer.
Electrically connected via.

In the semiconductor laser device of the present embodiment having the structure shown in FIG. 10, the p-side electrode layer 84 is formed in each of the two crystal planes that are inclined with respect to the principal surface of the substrate and are provided on both sides of the ridge.
85 is formed, for example, when the p-side electrode layers 84 and 85 are formed by using photolithography or the like, the distance between the electrodes can be set, which is advantageous in fine processing. In addition, the narrow openings 86, 87 formed in the insulating film 81.
Function as a current constriction portion, so that the laser element can be formed while suppressing variations in the emission wavelength, and a semiconductor laser element having a stable emission wavelength can be manufactured with good reproducibility.

By changing the heights of the openings 86 and 87 so that one is high and the other is low, an element structure capable of controlling a plurality of emission wavelengths is provided. It is also possible to form a plurality of pieces, such as two pieces on each side of the crystal plane inclined with the ridge line in between.

[Fourth Embodiment] FIG. 11 is a sectional view showing the device structure of a semiconductor laser device according to the fourth embodiment. The present embodiment is an example in which a magnesium-doped GaN layer is formed on each of two inclined surfaces facing each other with a ridge line in between.

A selective mask 92 made of, for example, a silicon oxide film is formed on a base body 91 whose main surface is a laminated body of a sapphire substrate and a base growth layer. The base 91 is a structure in which, for example, an undoped GaN layer and a silicon-doped GaN layer are stacked on a sapphire substrate whose main surface is the C surface. An AlN layer or the like may be formed as the buffer layer. An opening 93 having a stripe shape is formed in the selection mask 92 by hydrofluoric acid etching after forming a resist mask. Also in the present embodiment, the longitudinal direction of the opening 93 is, for example, the [1-100] direction or the [11-20] direction in order to obtain the crystal growth having the ridge line, as in the above-described embodiments.

From the elongated strip-shaped opening 93, silicon-doped Ga is formed as a first conductivity type semiconductor layer by selective growth.
The N layer 94 is formed. Also in this embodiment, as in the above-described embodiments, the silicon-doped GaN layer 94 has a substantially triangular cross section and grows from the elongated strip-shaped opening 93. Therefore, the direction perpendicular to the illustrated cross section is the longitudinal direction. To do. Resonance planes are formed by cleavage or etching at both ends (not shown) in the longitudinal direction, and laser oscillation becomes possible. In the silicon-doped GaN layer 94, the plane formed by the hypotenuse having a substantially triangular cross section serves as a crystal plane that is inclined with respect to the main surface of the substrate. During the growth of the silicon-doped GaN layer 94, its growth temperature is set to 980 ° C., for example.

On the silicon-doped GaN layer 94, I
n _0.05 Ga _0.95 N layer 95 is formed, for example, a thickness of 10nm as a guide layer, its _{an In 0.05} Ga
In _0.2 Ga as an active layer is formed on the _0.95 N layer 95.
_{The 0.8} N layer 96 is formed to have a film thickness of 3 nm, for example.
On the n _0.2 Ga _0.8 N layer 96 as a guide layer, In
_{0. The 05} Ga _0.95 N layer 97 is formed with a film thickness of 10 nm, for example. These In _{0. 05} Ga _0.95 N layer 9
5, In _0.2 Ga _0.8 N layer 96, and In _0.05
The Ga _0.95 N layer 97 is formed so as to be stacked on the inclined surfaces on both sides across the ridge line of the silicon-doped GaN layer 94 corresponding to the apex of the substantially triangular cross section.

In _0.05 Ga as a guide layer
_A magnesium-doped GaN layer 98 is formed as a second conductivity type semiconductor layer on the _0.95 N layer 97. In the present embodiment, the magnesium-doped GaN layer 98 is formed so as to cover only a part of the inclined surface instead of the whole area. A doped GaN layer 98 is formed. An insulating film 99 such as a silicon oxide film is formed in a region of the In _0.05 Ga _0.95 N layer 97 where the magnesium-doped GaN layer 98 is not formed. This insulating film 99 is formed so as to cover the semiconductor layer having a triangular cross section with a portion other than the magnesium-doped GaN layer 98. Here, the width on the slope of the magnesium-doped GaN layer 98 is set to be thin, for example, about 1 to 3 μm, and the magnesium-doped GaN layer 98 is formed into a thin strip pattern by etching or the like.

A p-side electrode layer 100 is formed on the magnesium-doped GaN layer 98 and the insulating film 99. The p-side electrode layer 100 is made of, for example, Ni / Pt / Au or Ni (P
d) / Pt / Au laminated structure. After the p-side electrode layer 100 is formed on the entire surface, it is formed so as to be electrically connected to at least the magnesium-doped GaN layer 98 by a method such as etching or lift-off. Since the magnesium-doped GaN layer 98 is already formed in a thin strip shape with a thickness of, for example, about 1 to 3 μm as described above, the p-side electrode layer 100 can be formed in a relatively wide area.

Next to the semiconductor layer having a triangular cross section, the n-side electrode layer 102 is formed in the opening 103 that opens the selection mask 92 and the insulating film 104. This n-side electrode layer 102
Has a Ti / Al / Pt / Au electrode structure, for example,
It is electrically connected to a silicon-doped GaN layer 94, which is a conductive semiconductor layer, via a base 91.

In the semiconductor laser device of the present embodiment having the structure shown in FIG. 11, the magnesium-doped GaN layer 98 having a narrow line width is formed in each of two crystal planes which are inclined with respect to the main surface of the substrate and are provided on both sides of the ridge. Since the insulating film 99 is formed so as to fill the periphery of the magnesium-doped GaN layer 98, even if the p-side electrode layer 100 is formed in a relatively wide region, it is a partial region that should emit light reliably. Can be formed, and when the p-side electrode layer 100 is formed by photolithography or the like, fine processing becomes easy. In addition, since the narrow magnesium-doped GaN layer 98 sandwiched between the insulating films 99 functions as a current constriction portion, it is possible to form a laser element while suppressing variations in emission wavelengths, respectively. A semiconductor laser device having a stable wavelength can be manufactured with good reproducibility.

In the present embodiment, the magnesium-doped GaN layer 98 is formed on both sides of the ridge, but it may be formed on one side. It is also possible to form a plurality of magnesium-doped GaN layers 98 in each inclined plane.

[Fifth Embodiment] FIG. 12 is a sectional view showing the device structure of a semiconductor laser device according to the fifth embodiment. This embodiment is an example in which an active layer having a narrow line width is formed on each of two inclined surfaces facing each other with a ridge line in between.

A selective mask 112 made of, for example, a silicon oxide film is formed on a substrate 111, which is a laminated body of a sapphire substrate and a base growth layer, having a main surface of the substrate. Base 111
Is a structure in which, for example, an undoped GaN layer and a silicon-doped GaN layer are stacked on a sapphire substrate whose main surface is the C plane. An AlN layer or the like may be formed as the buffer layer. In the selection mask 112, a striped opening 113 is formed by hydrofluoric acid etching after forming a resist mask. Also in the present embodiment, as in the above-described embodiments, in order to obtain the crystal growth with the ridge line in the longitudinal direction of the opening 113, for example, [1-10
0] direction or [11-20] direction.

From the elongated strip-shaped opening 113, silicon-doped G is formed as a first conductivity type semiconductor layer by selective growth.
The aN layer 114 is formed. Also in this embodiment, as in the above-described embodiments, the silicon-doped GaN layer 114 is used.
Has a substantially triangular cross section and grows from the elongated strip-shaped opening 113, so the direction perpendicular to the cross section is the longitudinal direction. Resonance planes are formed by cleavage or etching at both ends (not shown) in the longitudinal direction, and laser oscillation becomes possible. In the silicon-doped GaN layer 114, the plane formed by the hypotenuse having a substantially triangular cross section serves as a crystal plane that is inclined with respect to the main surface of the substrate. Silicon-doped GaN
When the layer 114 is grown, its growth temperature is, for example, 980.
Set to ° C.

On the silicon-doped GaN layer 114,
In _0.05 Ga _0.95 N layer 115 is formed, for example, a thickness of 10nm as a guide layer, its _{an In 0.05} Ga
_0. In _0.2 Ga as an active layer on the ₉₅ N layer 115.
_{The 0.8} N layer 116 is formed to have a film thickness of 3 nm, for example. In the present embodiment, the In _0.2 Ga _0.8 N layer 116 is formed in a thin strip-shaped pattern, and the upper and lower regions thereof are low-conductivity low-conductive layers 1 such as an undoped GaN layer.
17 is formed. It is also possible to form an insulating layer instead of the low conductive layer 117.

Low-conductivity layer 117 and In _0.2 Ga _0.8
In _0.05 Ga is formed as a guide layer on the N layer 116.
_{The 0.95} N layer 118 is formed to have a film thickness of 10 nm, for example. On the In _0.05 Ga _0.95 N layer 118,
Magnesium-doped GaN as the second conductivity type semiconductor layer
The layer 119 is formed and the magnesium-doped GaN layer 1 is formed.
A p-side electrode layer 120 is formed on 19. The p-side electrode layer 120 is, for example, Ni / Pt / Au or Ni (Pd) /
It has a laminated structure of Pt / Au. In ₀ to be the active layer
_{． Since the 2} Ga _0.8 N layer 116 is already formed in a thin strip shape as described above, the p-side electrode layer 120 can be formed in a relatively wide area.

Next to the semiconductor layer having a triangular cross section, an n-side electrode layer 122 is formed in an opening 123 that opens the selection mask 112 and the insulating film 124. This n-side electrode layer 12
2 has, for example, a Ti / Al / Pt / Au electrode structure, and is a silicon-doped GaN layer 11 which is a first conductivity type semiconductor layer.
4 is electrically connected via the base 111.

In the semiconductor laser device of the present embodiment having the structure shown in FIG. 12, the active layer of In.sub.0, which is a thin line width, is formed in each of two crystal planes which are inclined with respect to the main surface of the substrate and are provided on both sides of the ridge _{. 2} Ga _0.8 N layer 116 is formed and p
Even if the side electrode layer 120 is formed in a relatively wide area, it is possible to surely form a partial region that should emit light, and it is possible to easily form a fine region when forming the p-side electrode layer 120 using photolithography or the like. It can be processed. In addition, In _0.2 Ga having a narrow width formed by being sandwiched between the low-conductivity layers 117.
_{Since the 0.8} N layer 116 functions as an active layer, a laser element can be formed while suppressing variations in emission wavelength, and a semiconductor laser element having a stable emission wavelength can be manufactured with good reproducibility. .

In the present embodiment, In _0.2 Ga is used.
_{Although the 0.8} N layer 116 is formed on both sides of the ridge, it may be formed on one side. It is also possible to form a plurality of In _0.2 Ga _0.8 N layers 116 in each inclined plane.

[Sixth Embodiment] FIG. 13 is a cross-sectional view of essential parts of a gallium nitride-based compound semiconductor laser device of the present embodiment. A selective mask 132 made of, for example, a silicon oxide film is formed on a base 131, which is a laminated body of a sapphire substrate and a base growth layer, whose main surface is a substrate. Specifically, the base 131 is a structure in which, for example, an undoped GaN layer and a silicon-doped GaN layer are stacked on a sapphire substrate whose main surface is the C surface. An AlN layer or the like may be formed as the buffer layer. An opening 133 having a stripe shape is formed in the selection mask 132 by hydrofluoric acid etching after forming a resist mask. In the present embodiment, the longitudinal direction of the opening 133 is in the [1-100] direction or [11-20] direction in order to achieve crystal growth with ridges.
Direction.

From the elongated strip-shaped opening 133, silicon-doped G is formed as a first conductivity type semiconductor layer by selective growth.
The aN layer 134 is formed. In this embodiment, the silicon-doped GaN layer 134 has a substantially trapezoidal cross section,
In order to grow from the elongated strip-shaped opening 133, the direction perpendicular to the illustrated cross section is the longitudinal direction. The silicon-doped GaN layer 134 having a substantially trapezoidal cross section has a flat upper surface of, for example, C
The inclined surfaces on both sides are, for example, S surfaces. Resonance planes are formed by cleavage or etching at both ends (not shown) in the longitudinal direction, and laser oscillation becomes possible. In the silicon-doped GaN layer 134, the plane formed by the hypotenuse having a substantially trapezoidal cross section is a crystal plane inclined with respect to the main surface of the substrate. Silicon-doped GaN layer 134
The growth temperature is set to 980 ° C., for example.

On the silicon-doped GaN layer 134,
In _0.05 Ga _0.95 N layer 135 is formed, for example, a thickness of 10nm as a guide layer, its _{an In 0.05} Ga
_0. In _0.2 Ga as an active layer on the ₉₅ N layer 135.
_{The 0.8} N layer 136 is formed to have a film thickness of 3 nm, for example, and the In _0.05 Ga _0.95 N layer 137 as a guide layer is formed on the In _0.2 Ga _0.8 N layer 136 to have a film thickness of 10 nm, for example.
nm. These In _0.05 Ga _0.95 N
Layer 135, In _0.2 Ga _0.8 N layer 136, and In
_{The 0.05} Ga _0.95 N layer 137 is formed so as to be stacked on the inclined surfaces on both sides of the silicon-doped GaN layer 134 which is the apex of the substantially trapezoidal cross section and the upper surface parallel to the main surface of the substrate.

In _0.05 Ga as a guide layer
_A magnesium-doped GaN layer 138 is formed as a second conductivity type semiconductor layer on the _0.95 N layer 137. The magnesium-doped GaN layer 138 is a layer functioning as a second conductivity type semiconductor layer and is a p-type compound semiconductor layer. An insulating film 139 such as a silicon oxide film is formed on the magnesium-doped GaN layer 138. The insulating film 139 is formed so as to cover the semiconductor layer having a trapezoidal cross section, and an opening 140 is formed by opening a part on the inclined surface of the insulating film 139. The opening 140 extends in the horizontal direction, and faces the semiconductor layer at the height where the opening 140 exists. The width of the opening 140 on the slope is set to be thin, for example, about 1 to 3 μm.

A p-side electrode layer 141 is formed in the region where the opening 140 is formed. The p-side electrode layer 141 is, for example, N
It has a laminated structure of i / Pt / Au or Ni (Pd) / Pt / Au. After the p-side electrode layer 141 is formed on the entire surface, it is formed into a thin strip pattern by a method such as etching or lift-off. The p-side electrode layer 141 partially formed on this inclined surface is, for example, 1 to 3 as described above.
It should be deposited on the interface of the magnesium-doped GaN layer 138 through an opening 140 that is thinly opened to about μm, and should supply current intensively to a predetermined height portion of a semiconductor layer having a trapezoidal cross section and emit light. The region is a partial region limited in the width direction of the slope.

Next to the semiconductor layer having a trapezoidal cross section, a selection mask 132 and an insulating film 139 are opened, and the n-side electrode layer 14 is formed.
2 is formed. The n-side electrode layer 142 is formed of, for example, Ti /
It has an Al / Pt / Au electrode structure and is electrically connected to the silicon-doped GaN layer 134 that is the first conductivity type semiconductor layer through the base 131.

In such a semiconductor laser device, since the narrow opening 140 formed in the insulating film 139 functions as a current constriction part, it is possible to form a laser device while suppressing variations in emission wavelength. Therefore, it is possible to manufacture a semiconductor laser device having a stable emission wavelength with good reproducibility. Note that the p-side electrode layer 141 can be additionally formed on the other inclined surface, and a plurality of electrode layers can be provided on each inclined surface having the trapezoidal cross section. In these examples, the electrode portion is partially thermally activated (a mask is formed and only the mask opening is activated), or hydrogen ions are implanted in a portion other than the stripe portion so that a current flows only in the stripe. As a result, the current injection portion can be formed.

[0090]

According to the semiconductor laser device of the present invention,
Since the narrow electrode layer, semiconductor layer, active layer, etc. function as a partial region in the crystal plane tilted with respect to the main surface of the substrate, it is possible to form a laser element while suppressing variations in emission wavelength. Therefore, a semiconductor laser device having a stable emission wavelength can be manufactured with good reproducibility. Further, according to the semiconductor laser device of the present invention, since the crystal plane tilted with respect to the main surface of the substrate is used for light emission, it is possible to increase the current density while suppressing crystal dislocations, and to provide a semiconductor laser device with high brightness. It can be manufactured.

[Brief description of drawings]

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

FIG. 2 is a schematic diagram for explaining a partial region of the semiconductor laser device according to the first embodiment of the present invention.

FIG. 3 is a process perspective sectional view in the method for manufacturing a semiconductor laser device according to the first embodiment of the present invention, which is a process perspective sectional view up to a process of forming an opening.

FIG. 4 is a perspective cross-sectional view of steps in the method for manufacturing a semiconductor laser device according to the first embodiment of the present invention, which is a perspective perspective view of steps up to the step of forming a silicon-doped GaN layer.

FIG. 5 is a process perspective sectional view in the method for manufacturing a semiconductor laser device according to the first embodiment of the present invention, showing V of FIG.
FIG. 6 is a cross-sectional view taken along the line −V and is a process perspective cross-sectional view up to the process of forming a silicon-doped GaN layer.

FIG. 6 is a process perspective sectional view in the method for manufacturing a semiconductor laser device according to the first embodiment of the present invention, which is a process perspective sectional view up to the process of forming a magnesium-doped GaN layer.

FIG. 7 is a process perspective sectional view in the method for manufacturing a semiconductor laser device according to the first embodiment of the present invention, which is a process perspective sectional view up to a process of forming an opening.

FIG. 8 is a process perspective sectional view in the method for manufacturing a semiconductor laser device according to the first embodiment of the present invention, which is a process perspective sectional view up to the process of forming a p-side electrode layer.

FIG. 9 is a sectional view showing an element structure of a semiconductor laser element according to a second embodiment of the present invention.

FIG. 10 is a sectional view showing a device structure of a semiconductor laser device according to a third embodiment of the present invention.

FIG. 11 is a sectional view showing an element structure of a semiconductor laser element according to a fourth embodiment of the present invention.

FIG. 12 is a sectional view showing an element structure of a semiconductor laser element according to a fifth embodiment of the present invention.

FIG. 13 is a sectional view showing an element structure of a semiconductor laser element according to a sixth embodiment of the present invention.

FIG. 14 is a characteristic diagram showing the relationship between the wavelength and the length from the bottom of the semiconductor laser device according to the present invention.

[Explanation of symbols]

11, 31, 51, 71, 91, 111, 131 Bases 12, 32, 52, 72, 92, 112, 132 Selection masks 13, 33, 53, 73, 93, 113, 133 Openings 14, 34, 54, 74, 94, 114, 134 Silicon-doped GaN layers 15, 35, 55, 75, 95, 115, 135 In
_0.05 Ga _0.95 N layer 16, 36, 56, 76, 96, 116, 136 I
n _0.2 Ga _0.8 N layer 17, 37, 57, 77, 97, 118, 137 I
n _0.05 Ga _0.95 N layer 18, 38, 58, 78, 98, 119, 138 Magnesium-doped GaN layer 19, 41, 64, 65, 84, 85, 100, 12
0, 141 p-side electrode layers 22, 42, 62, 82, 102, 122, 142 n
Side electrode layer

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Takeshi Biwa             6-735 Kita-Shinagawa, Shinagawa-ku, Tokyo Soni             -Inside the corporation (72) Inventor Toyoji Ohata             6-735 Kita-Shinagawa, Shinagawa-ku, Tokyo Soni             -Inside the corporation F term (reference) 5F045 AA02 AA04 AA05 AB17 AC08                       AC09 AC12 AD10 AF02 AF03                       AF04 AF05 AF06 AF09 BB02                       BB03 BB12 BB16 CA12 DA61                       DB02                 5F073 AA04 AA11 AA55 AA61 AB05                       AB06 BA09 CA07 CB05 CB06                       DA05 DA23 EA29

Claims (18)

[Claims] 1. A structure having an active layer extending along a crystal plane inclined with respect to a main surface of a substrate, sandwiched by a first conductive type semiconductor layer and a second conductive type semiconductor layer, and substantially perpendicular to the crystal plane. Is a resonance surface, and the light emitting region is a partial region within the inclined surface of the active layer. 2. The semiconductor laser device according to claim 1, wherein the crystal plane inclined with respect to the main surface of the substrate is formed by selective growth from the substrate. 3. The width of the partial region in the in-plane direction has a variation in the emission wavelength of the semiconductor laser device of about 10 nm.
2. The range is set as follows:
The semiconductor laser device described. 4. The semiconductor laser device according to claim 1, wherein the partial region has a width of about 3 μm or less in the in-plane direction. 5. The partial region is formed by forming an electrode for supplying a current to the active layer so as to have a predetermined width in a direction within an inclined plane. Semiconductor laser device. 6. The semiconductor laser device according to claim 5, wherein the electrode is formed in a portion where an insulating film is opened in a stripe shape. 7. The partial region is formed such that at least one of the first conductive type semiconductor layer and the second conductive type semiconductor layer sandwiching the active layer has a predetermined width in a direction within an inclined plane. The semiconductor laser device according to claim 1, wherein the semiconductor laser device is composed of: 8. The semiconductor laser device according to claim 1, wherein the partial region is formed by forming the active layer so as to have a predetermined width in a tilt direction within a tilt plane. 9. The semiconductor laser device according to claim 1, wherein the partial region is formed at one location in a direction within an inclined surface. 10. The semiconductor laser device according to claim 1, wherein the partial region is formed at a plurality of positions in a direction within an inclined surface. 11. An active layer extending along a crystal plane inclined with respect to a main surface of a substrate is sandwiched by a first conductive type semiconductor layer and a second conductive type semiconductor layer, and the active layer and the first conductive type semiconductor are sandwiched. A layer and the second conductivity type semiconductor layer are formed in a substantially triangular shape in a cross section substantially perpendicular to the crystal plane, and an end surface substantially perpendicular to the crystal plane is a resonance plane, and a region emitting light is A semiconductor laser device, characterized in that it is a partial region within an inclined plane of the active layer. 12. The semiconductor laser device according to claim 11, wherein the partial region is formed on one inclined surface of the substantially triangular shape. 13. The semiconductor laser device according to claim 11, wherein the partial region is formed on both inclined surfaces of the substantially triangular shape. 14. An active layer extending along a crystal plane inclined with respect to a main surface of a substrate is sandwiched between a first conductive type semiconductor layer and a second conductive type semiconductor layer, and the active layer and the first conductive type semiconductor are sandwiched. A layer and the second conductivity type semiconductor layer are formed in a substantially trapezoidal shape in a cross section substantially perpendicular to the crystal plane, an end surface substantially perpendicular to the crystal plane is a resonance surface, and a region for emitting light is A semiconductor laser device, characterized in that it is a partial region within an inclined plane of the active layer. 15. A step of forming, on a substrate, a first conductivity type semiconductor layer having a crystal plane inclined with respect to a main surface of the substrate by selective growth, and a step of forming an active layer on the first conductivity type semiconductor layer. And a step of forming a second conductive type semiconductor layer on the active layer, and a step of forming an electrode layer in contact with the second conductive type semiconductor layer on a part of an inclined surface on the second conductive type semiconductor layer. A method for manufacturing a semiconductor laser device, comprising: 16. The method of manufacturing a semiconductor laser device according to claim 15, further comprising the step of forming an insulating film having an opening in the part before forming the electrode layer. 17. The semiconductor laser device according to claim 15, wherein the electrode layer is formed on the entire surface and then removed except for a region that is partially in contact with the second conductivity type semiconductor layer. Production method. 18. The semiconductor laser device of claim 15, wherein the second conductive type semiconductor layer is formed on the entire surface and then removed except for a region which is partially in contact with the electrode layer. Production method.