JPH0637395A - Semiconductor laser device - Google Patents

Abstract

PURPOSE:To provide a surface emission type semiconductor laser device which has approximately the same light output-current characteristics as a semiconductor laser device formed by cleaving, can take out a light free from aberration and shading along a direction accurately perpendicular to the surface of a semiconductor substrate and facilitates two-dimensional integration. CONSTITUTION:At least a first conductivity type cladding layer 2, an active layer 3 and a second conductivity type cladding layer 4 are provided on a semiconductor substrate 1. Crystal growth surfaces which have 45 deg. angles from the main surface 1S of the semiconductor substrate 1 are provided as reflective mirror surfaces 12A and 12B against the end surfaces 11A and 11B of a resonator formed by vertical etching.

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, and more particularly to a so-called surface emitting semiconductor laser device for extracting laser light in a direction perpendicular to the surface of a semiconductor substrate.

[0002]

2. Description of the Related Art Semiconductor lasers have been widely put to practical use as light sources for optical disks, optical fiber communications, etc., and further improved in characteristics such as higher coherence and higher output, and monolithically integrated with functional devices such as optical modulators. Is being promoted. In recent years, in particular, in consideration of application to parallel optical information processing in optical computers or the like, or large-capacity parallel optical transmission, realization of large-scale two-dimensional integration is desired. However, it is extremely difficult to monolithically integrate a semiconductor laser having a conventional configuration because a performance test cannot be performed without element isolation.

For example, when the light emitting end face is formed by vertical etching or the like, the laser light is emitted in parallel with the surface of the substrate, so that two-dimensional integration cannot be performed as it is, and the emitted light is shielded by the surface of the substrate. There is a problem that so-called vignetting occurs such as reflection on the surface of the substrate and interference.

On the other hand, as a semiconductor laser which can be two-dimensionally integrated, a surface emitting laser which emits laser light in a direction perpendicular to the substrate surface has been receiving attention. As such a surface-emitting laser, for example, a reflecting mirror surface that makes an angle of 45 ° with the substrate is provided facing the light emitting end surface of a normal semiconductor laser, and the laser light is reflected by the reflecting mirror surface with respect to the substrate surface. The structure is taken out in the vertical direction. In order to form such a surface emitting laser as a monolithic structure, anisotropic dry etching is generally used, for example, in a direction perpendicular to the substrate with respect to a semiconductor layer formed on the substrate. 2 from an angle of about 2 °
By carrying out anisotropic etching once, the surface emitting laser and the reflecting mirror surface can be formed to obtain a surface emitting laser.

For example, when an InP-based semiconductor laser is formed, the mass transport method (Z. Liau et.al Appl.Ph
ys.Lett.46 (1985) p.115), ion beam assisted etching (IBAE) method for GaAs (THWindho
rn et.al Appl.Phys.Lett.48 (1986) p.1675), chemical etching method (AJSpringThorpe Appl.Phys.Lett.31 (1977)
p.524) or reactive ion beam etching (RIB
E) There is a report formed using the method (T. Yuasa et.al CLEO '88wo6 4/27) and the like. In these lasers, for example, as described in the report using the above-mentioned IBAE method, the threshold value is higher than that in a laser using a normal cleavage plane,
There is a problem that the output is inferior.

That is, in the case of these methods, it is difficult to form a reflecting mirror surface by anisotropic etching from an oblique direction with flatness on the order of an atomic layer, and it is difficult to form an inclination angle with high precision. There is an inconvenience that deviation of the emission angle of V from the vertical direction or aberration occurs.

On the other hand, for example, a reflective surface, a clad layer, an active layer, a clad layer and a reflective surface are sequentially laminated on the substrate,
There has been proposed a vertical cavity surface emitting laser in which a resonator is formed in a direction perpendicular to a substrate surface and laser light is emitted in a vertical direction. In the semiconductor laser having such a laminated structure, since the resonator is formed in the vertical direction, it is not possible to obtain a sufficient gain with a large cavity (gain region length), and at present, a sufficiently high optical output cannot be obtained. , Has not been put to practical use.

On the other hand, as a semiconductor laser having a low threshold current, an SDH (Separated Double Hetero junction) which can be formed by a single epitaxial growth operation.
tion) A semiconductor laser is disclosed in Japanese Patent Application Laid-Open No.
Japanese Patent Application No. 1-183987, JP-A-2-174287
No. Patent application etc.

As shown in FIG. 12 which is an enlarged schematic cross-sectional view of an example of this SDH type semiconductor laser, first, GaAs of the first conductivity type, for example, n type, and one main surface 1S of which is a {100} crystal face is used. On the main surface 1S of the semiconductor substrate 21 made of
For example, stripe-shaped mesa protrusions or ridges 22 extending in the <011> crystal axis direction orthogonal to the paper surface of FIG. 12 are formed by sandwiching both sides of the ridges 22 with grooves 22A. On the surface 21S, a first conductivity type, for example, n-type AlGaAs is successively formed on the surface 21S by a normal methyl-based MOCVD (Chemical Vapor Deposition) method.
And the like, an active layer 24 made of GaAs or AlGaAs having a low impurity concentration or undoped, a first cladding layer 25 made of second conductivity type, for example, p-type AlGaAs, and n-type AlGaAs.
And the second conduction type, for example, n.
The second clad layer 27 made of AlGaAs or the like, for example, each semiconductor layer of the p-type cap layer 29 is formed by one epitaxial growth operation.

At this time, as described above, the crystal plane of the main surface 21S of the substrate 21 and the crystal orientation in which the ridge 22 extends are selected, and further, the width and height of the ridge 22, that is, the depth of the grooves 22A on both sides thereof, Further, the n-type clad layer 23 and the active layer 2
4. By selecting the thickness of the p-type first cladding layer 25, etc., the slopes 28A are formed so that the layers 23, 24 and 25 are separated from each other on the ridge 22 and the groove 22A.
And 28B can be formed.

This is because, in the MOCVD method using a methyl-based organic metal as a source gas, once the {111} B crystal plane is generated, it is difficult for epitaxial growth to occur on this plane. The reason is that the epitaxial growth layer 30 having a triangular cross section divided by the inclined surfaces 28A and 28B and extending in the direction orthogonal to the paper surface of FIG. 8 is formed.

In this case, the current blocking layer 26 is divided by the epitaxial growth layer 30 into both sides with the epitaxial growth layer 30 sandwiched therebetween, and both end faces generated by this division are just in the vicinity of both end faces of the active layer 24, that is, slopes 28A and 28B. It is made to butt to cover the end face that faces.

In this way, the active layer 23 in the epitaxial growth layer 30 on the ridge 22 is formed so as to be sandwiched by the current blocking layers 26 having a smaller refractive index than that, and a laterally confined light emitting operation region is formed. The presence of the current blocking layer 26 causes the n-type cladding layer 23 and the p-type first epitaxial layer 30 to be formed on both outer sides of the stripe-shaped epitaxial growth layer 30.
Clad layer 25, blocking layer 26, and p-type second clad layer 27 form an np-n-p thyristor for blocking current therethrough, which causes the active layer on the ridge 22 to be blocked. The current is concentrated on 24 to reduce the threshold current.

However, even in the low threshold semiconductor laser having such an SDH type structure, the surface emitting type structure for extracting the laser light in the direction perpendicular to the substrate has not been embodied, and the surface emitting type structure can be used for two-dimensional integration. Realization is desired.

[0015]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems in a surface emitting laser that extracts laser light in a direction perpendicular to the main surface of a substrate, that is, a semiconductor laser device by cleavage. It has the same optical output-current characteristics, and the aberration is accurately perpendicular to the surface of the semiconductor substrate.
A semiconductor laser device capable of extracting light without vignetting and capable of two-dimensional integration.

[0016]

The semiconductor laser of the present invention comprises:
As shown in FIG. 1 which is an enlarged schematic perspective view of an example thereof, at least a first conductivity type cladding layer 2 is formed on a semiconductor substrate 1.
And an active layer 3 and a second-conductivity-type clad layer 4, facing the cavity end faces 11A and 11B formed by vertical etching, and having a thickness of approximately 4 with respect to the main surface of the semiconductor substrate 1.
Reflective mirror surfaces 12A and 12 are used as crystal growth surfaces forming an angle of 5 °.
Configure as B.

In the semiconductor laser device described with reference to FIG. 1, the present invention has a main surface of the semiconductor substrate 1 of {10.
0} crystal plane, and the resonator length direction indicated by arrow A is <01
0> The crystal growth {110} crystal plane is formed as the reflecting mirror surfaces 12A and 12B by selecting the crystal axis direction.

Alternatively, according to the present invention, the reflecting mirror surfaces 12A and 12B composed of {110} crystal planes are formed on the semiconductor substrate 1 in {10}.
0} crystal plane is defined as a crystal plane grown by an edge portion 7E of a growth inhibiting layer 7 that inhibits crystal growth, and the edge portion 7E of the growth inhibiting layer 7 has a <001> crystal axis. Direction, and is formed so as to project in the <010> crystal axis direction.

Further, according to the present invention, as shown in FIG. 3 which is a schematic enlarged perspective view of an example thereof, the semiconductor substrate 1 is moved from the {100} crystal plane by about 9 in the <0-11> crystal axis direction indicated by the arrow C. .7
° off-substrate tilted,
Approximately 9.7 ° from the 1> crystal axis direction to the <100> crystal axis direction.
The crystal growth {111} B crystal planes are formed as the reflecting mirror surfaces 12A and 12B by selecting the inclined direction.

Further, the semiconductor laser device of the present invention has a schematic enlarged perspective view of an example thereof, as shown in FIG. 4, in which at least a first conductivity type cladding layer 2 and an active layer 3 are provided on a semiconductor substrate 1. , A second conductivity type cladding layer 4 and
Resonator end faces 11A and 11 formed by vertical etching
The semiconductor substrate 1 has a first reflecting mirror surface 18 formed by vertical etching for extracting the laser light emitted from B in a direction along the main surface of the semiconductor substrate 1. Has a second reflecting mirror surface 19 composed of a crystal growth surface taken out in a direction perpendicular to the main surface of the.

Further, according to the present invention, in the above-mentioned semiconductor laser device, the semiconductor substrate 1 is formed from the {100} crystal plane to <0-1.
1> It is composed of an off substrate tilted by about 9.7 ° to the crystal axis direction, the resonator length direction is selected as the <011> crystal axis direction, and the first reflecting mirror surface 18 is set at about 45 ° from the resonator length direction. The crystal growth {111} B crystal plane is formed as the second reflecting mirror surface 19.

Furthermore, the present invention is configured by providing the ridge 20 extending in the <011> crystal axis direction on the semiconductor substrate 1 in the semiconductor laser device shown in FIG.

Further, the semiconductor laser device of the present invention has a semiconductor substrate 1 as shown in FIG.
Of the principal plane of the {100} crystal plane, the resonator length direction is selected as the <011> crystal axis direction, and the first reflecting mirror surface 18 forms approximately 22.5 ° from the resonator length direction. That is, it is provided so as to form an angle of 67.5 ° with respect to the resonator end surface 11A or 11B (not shown), and the crystal growth {110} crystal plane is configured as the second reflecting mirror surface 19.

Furthermore, the present invention is constructed by providing a ridge extending in the <011> crystal axis direction on the semiconductor substrate in the semiconductor laser device shown in FIG.

[0025]

According to the present invention, the cavity facets are formed by vertical etching or crystal growth, and in particular, the reflecting mirror surfaces 12A and 12B which are spontaneously obtained by crystal growth and which form substantially 45 ° with respect to the substrate are utilized. Then, a semiconductor laser device capable of efficiently extracting emitted light in a direction perpendicular to the semiconductor substrate 1 is provided.

That is, according to the present invention, as shown in FIG. 1, the main surface of the semiconductor substrate 1 is a {100} crystal plane and the resonator length direction is selected as the <010> crystal axis direction. In the structure, when the crystal is grown by the MOCVD method or the like, the {110} crystal plane is spontaneously generated from the edges on the cavity end faces 11A and 11B. This will be described below.

As shown in FIG. 6A, the semiconductor substrate 1 {1
After the resist 33 extending in the <001> crystal axis direction is formed on the main surface 1S composed of the (00) crystal planes by pattern exposure or the like, GaAs, AlGaAs, InP, InAlG is formed by MOCVD, MBE or low pressure MOCVD.
When crystal growth of the semiconductor layer 34 such as aP is performed, the resist 3
Once the {110} crystal plane spontaneously occurs from the edge of No. 3, the growth rate is relatively slow on this {110} crystal plane. Therefore, as shown in FIG. 6B, it extends from the edge of the resist 33. As a result, a {110} crystal plane forming an angle of 45 ° with the main surface 1S is formed. Further, not limited to the resist, if a ridge or a groove, an opening covered with a mask, or the like is formed as a pattern extending in the <001> crystal axis direction similarly to the resist 33 described above, the main surface 1S is spontaneously generated similarly. {110} crystal planes that form an angle of 45 ° with respect to, for example, a slope 35A composed of the (1-10) plane and a slope 35B composed of the (110) plane.
It was revealed as a result of the diligent study by the present inventors that the formation of the above phenomenon occurs.

Therefore, as shown in FIG.
By constructing the 0} crystal planes as the reflecting mirror surfaces 12A and 12B, the laser light emitted from the active layer 3 is generated as shown in FIG.
Can be taken out in the <100> crystal axis direction indicated by arrow B, that is, in the direction substantially perpendicular to the substrate 1.

In this case, since the surface is a crystal growth surface, the flatness of the surface and the controllability of the angle are better than in the case where the reflecting mirror surface is formed by the conventional dry or wet etching such as the above-mentioned RIBE method or IBAE method. Is remarkably excellent, and since it can be formed under the growth conditions similar to those of ordinary semiconductor lasers, it is extremely versatile and simple.

According to the present invention, in the above-mentioned structure, the growth blocking layer 7 for blocking the crystal growth is provided on the resonator end faces 11A and 11B as shown in FIG.
E is provided so as to extend in the <001> crystal axis direction so as to project in the <010> crystal axis direction, and the surfaces on which crystals are grown from this edge portion 7E are used as reflecting mirror surfaces 12A and 12B. , 11B and reflecting mirror surfaces 12A, 12
B can be made to face each other while being separated from each other, and the light emitted from the resonator end faces 11A and 11B can be reflected by the reflecting mirror surface 12
After being reflected by A and 12B, vignetting due to the growth blocking layer 7 and the like can be surely avoided, and laser light can be efficiently extracted in a direction perpendicular to the substrate 1.

In another embodiment of the present invention, as shown in FIG. 3, the semiconductor substrate 1 is indicated by an arrow C from the {100} crystal plane <0-.
11> It is composed of an off-substrate tilted by about 9.7 ° with respect to the crystal axis direction, and the resonator length direction is <10-11 from the crystal axis direction.
0> It is selected in a direction inclined by about 9.7 ° with respect to the crystal axis direction. In this case as well, the crystal face is grown by the MOCVD method or the like so that the cavity facets 11A and 11B are
{111} B will spontaneously occur at the position opposite to. The {111} B crystal plane forms an angle of about 54.7 ° with respect to the {100} crystal plane, and in this case, the substrate 1 is oriented from the {100} crystal plane to the <0-11> crystal axis by about 9.
Since the off substrate tilted by 7 ° is used, {111}
The B crystal plane forms an angle of about 45 ° with the main surface 1S of the substrate 1. Therefore, by configuring the {111} B crystal planes as the reflecting mirror surfaces 12A and 12B, the laser light can be extracted in a direction substantially perpendicular to the main surface 1S of the substrate 1 as shown by an arrow D.

Furthermore, according to the present invention, as shown in FIGS. 4 and 5, at least a first conductivity type cladding layer 2, an active layer 3, and a second conductivity type cladding layer 4 are provided on a semiconductor substrate 1. A first reflection mirror surface 18 formed by vertical etching for extracting laser light emitted from the cavity end faces 11A and 11B formed by vertical etching in a direction along the main surface of the semiconductor substrate 1. The second growth plane 19 has a crystal growth surface for extracting the light reflected from the first reflection mirror surface 18 in a direction perpendicular to the main surface of the semiconductor substrate 1, and thereby the laser light is efficiently emitted in the vertical direction. Can be taken out.

In such a semiconductor laser device, the semiconductor substrate 1 is formed from the {100} crystal plane to <0-11>.
The off-substrate tilted by about 9.7 ° in the crystal axis direction is provided, and the first reflecting mirror surface 18 is provided at an angle of about 45 ° from the cavity length direction.
The laser light is accurately extracted in the vertical direction by forming the spontaneously generated {111} B crystal plane forming an angle of 45 ° with respect to the substrate 1 as the second reflecting mirror surface 19 along the horizontal direction along the line. be able to.

In another embodiment of the present invention, a ridge 22 extending in the <011> crystal axis direction is formed on the substrate 1,
Since each semiconductor layer is epitaxially grown on this, a semiconductor laser having an SDH type structure in which the active layer is laterally confined as described above with reference to FIG. It is possible to obtain a surface-emitting laser device that has been optimized.

Alternatively, in the present invention, the main surface of the semiconductor substrate 11 is composed of {100} crystal faces, and the first reflecting mirror surface 18 is provided at an angle of approximately 22.5 ° from the cavity length direction. , The laser light is extracted along the main surface 1S of the substrate 1 in a direction forming an angle of about 45 ° from the cavity length direction,
Further, since the crystal growth {110} crystal plane spontaneously formed along the direction forming an angle of about 45 ° from the cavity length direction is configured as the second reflecting mirror surface 19, the main surface 1S of the substrate 1 is formed. With the second reflecting mirror surface 19 forming an angle of 45 ° with respect to, laser light can be extracted in a direction perpendicular to the substrate 1.

In yet another embodiment of the present invention, the substrate 1
Since the ridge 22 extending in the <011> crystal axis direction is formed on the upper surface of the ridge 22, the semiconductor light emitting device of SDH type having the lower threshold value is similarly used to reduce the surface emission. A laser device can be obtained.

As described above, in the present invention, since a large number of semiconductor laser devices can be obtained without cleavage, two-dimensional integration is possible, and an oblique reflecting mirror surface for extracting laser light in the vertical direction is provided. Since the structure can be formed spontaneously by crystal growth, it is possible to accurately extract light without aberration and vignetting in the direction perpendicular to the surface of the semiconductor substrate.

[0038]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Each example of the semiconductor laser device of the present invention will be described in detail below with reference to the drawings.

First, with reference to FIG. 1, an example of the present invention will be described together with a manufacturing method for easy understanding. In this example, after forming a current blocking layer on the active layer via the cladding layer, the effective refractive index near the waveguide region is removed by etching away the waveguide region near the current blocking layer. A case where a so-called SAN (Self-Aligned Narrow stripe) type configuration in which light is confined at the same time as current confinement is adopted is shown.

In FIG. 1, 1 is a semiconductor substrate made of, for example, n-type GaAs of the first conductivity type, and 1S is its {10.
A major surface of the (0) crystal planes is, for example, a (100) crystal plane, 2 is a first-conductivity-type cladding layer made of, for example, n-type AlGaAs, 3 is an active layer made of, for example, intrinsic GaAs, and 4 and 6 are, for example. Second type consisting of p-type AlGaAs
The conductivity type cladding layer, 5 is a first conductivity type current blocking layer made of, for example, n type GaAs, 7 is a growth blocking layer made of SiN _x, etc., and 8 is, for example, p type GaA formed by re-growth.
A second-conductivity-type crystal growth layer, which is made of s and grows at an angle of 45 ° with respect to the main surface 1S of the substrate 1, and 9 denotes an electrode in ohmic contact with the crystal growth layer 7. In this case, the resonator end faces 11A and 11B are formed by vertical etching such as RIE so that the resonator extends in, for example, the [010] crystal axis direction of the <010> crystal axis direction indicated by the arrow A in FIG. It becomes, and opposes this {1
Substrate 1 having, for example, a (110) crystal plane of a 10} crystal plane
The crystal growth surface forming an angle of 45 ° with respect to the main surface 1S of
2A and 12B. Reference numeral 10 is a highly reflective film made of a metal or dielectric multilayer film deposited on one of the reflecting mirror surfaces 12A.

An example of the manufacturing process of such a semiconductor laser device will be described with reference to FIGS. First, as shown in FIG. 7A, a semiconductor substrate 1 made of GaAs or the like of the first conductivity type, in this case, n-type, is prepared, and is sequentially formed on the main surface 1S made of {100} crystal faces of the substrate 1 by, for example, MOCVD method. The first conductive clad layer 2 made of n-type AlGaAs, the active layer 3 made of intrinsic GaAs, and the p-type AlG
Second-conductivity-type cladding layer 4 made of aAs or the like, n-type AlG
The current blocking layer 5 made of aAs or the like is sequentially formed, for example, by MOCVD.
Grow by law.

Then, after that, a resist mask (not shown) is formed on the portion to be the waveguide region 50, and as shown in FIG. 7B, a part of the current blocking layer 5 is removed by wet etching or the like. In this case, the removal portion of the blocking layer 5 is patterned as a pattern extending in the direction orthogonal to the paper surface indicated by the arrow A in FIG. 7B so as to extend in the <010> crystal axis direction. Then, a second conduction type cladding layer 6 made of, for example, p-type AlGaAs is epitaxially grown on the entire surface so as to cover the same by MOCVD or the like. By doing so, current confinement is made in the removed portion of the current blocking layer 5, and the refractive index of this neighboring region is larger than that of the other portions, so that light is confined.

FIG. 7C is a sectional view taken along line aa in FIG. 7B.
As shown in FIG. 5, vertical etching perpendicular to the main surface 1S of the substrate 1 is performed by anisotropic etching such as RIE with a predetermined resonator length L _c to a depth reaching the substrate 1, and an arrow A
A resonator extending in the <010> crystal axis direction is formed. Reference numerals 11A and 11B denote resonator end faces formed by vertical etching.

After this, a protective material film made of, for example, SiN _x is deposited over the entire surface, and then vertical etching is performed over the entire surface by RIE or the like to form the second conductivity type clad layer 6 and the main surface of the substrate 1. The protective material on 1S is removed, leaving only the side wall, and as shown in FIG. 8A, a protective film 15 is formed on the resonator end faces 11A and 11B by deposition. Further, on the protective film 15 and the second-conductivity-type cladding layer 6, a p-type G
After depositing the material layer made of aAs or the like, the cap layer 16 is deposited by applying photolithography.

Next, the entire surface is covered with SiO ₂ so as to cover it.
After depositing a dielectric layer such as Si ₃ N ₄ or the like by a plasma chemical deposition method or the like, RIE is performed in a direction perpendicular to the main surface 1S of the substrate 1.
Etching is performed anisotropically to leave the sidewalls alone, and form the growth blocking layer 7 so as to cover the resonator end faces 11A and 11B and the protective film 15 thereon. Then, as shown in FIG. 8B, the cap layer 16 on the second conductivity type cladding layer 6 is removed by selective etching.

After that, according to, for example, an atmospheric pressure MOCVD method such as an MOCVD method, an MBE method or a low pressure MOCVD method, a normal growth condition, that is, a growth temperature of 780 ° C. or more, a V / III ratio (atoms of a group V element and a group III element) (The number ratio) is 20 or more, and the second-conductivity-type crystal growth layer 8 is made of, for example, p-type GaAs.
Is epitaxially grown, and as shown in FIG. 8C, it is composed of {110} crystal planes facing the cavity end faces 11A and 11B formed by vertical etching and forming an angle of about 45 ° with the main surface of the semiconductor substrate. Reflecting mirror surfaces 12A and 12
Form B. This is the main surface 1 of the substrate 1 as described above.
By properly selecting S and the cavity length direction, the growth rate is extremely slow on this {110} crystal plane.
It is obtained spontaneously. In this case, when the cavity length direction to the left in the diagram indicated by the arrow A is the [010] crystal axis direction, the reflecting mirror surface 12A is the (1-10) crystal surface,
The reflecting mirror surface 12B becomes a (110) crystal plane.

As described above, in the present invention, the reflecting mirror surface 1
Since 2A and 12B can be used as the crystal growth surface, the flatness of the surface and the controllability of the angle can be remarkably improved as compared with the conventional case. Further, in this case, since it is possible to form under the same temperature condition as that of a normal semiconductor laser and the growth condition such as V / III ratio without adopting a method which is relatively difficult to grow such as diffusion due to extremely high temperature, It is extremely advantageous in terms of versatility and simplicity.

Then, as shown in FIG. 1, an electrode 9 which is ohmic-connected to the upper surface of the crystal growth layer 8 on the active layer 3 and the back surface of the substrate 1 (not shown) is deposited, and one of the reflections is reflected, for example. Highly reflective film 10 made of a dielectric or the like on the mirror surface 12A
Then, the semiconductor laser device of the present invention can be obtained.

When a current is injected into such a laser device, a resonator is formed between the two vertical end faces 11A and 11B to cause laser oscillation, and the main surface 1S of the substrate 1 is temporarily cut.
The light emitted in parallel with is the mirror surface 12A of 45 °.
And 12B, the light is reflected in the direction perpendicular to the substrate 1, and surface emission is realized.

Further, in this case, since the SAN type structure is adopted, the current is confined and the light is confined in the lateral direction, so that the surface emitting laser having a lower threshold value can be obtained.

In this case, the example of the SAN type structure has been described. In addition, as shown in FIG. 9, a striped guide layer 41 extending in the cavity length direction is provided on the active layer 3 so as to cover it. The present invention can also be applied to a semiconductor laser device having a so-called Rib type structure in which the second conductivity type cladding layer 4, the current blocking layer 5 and the like are sequentially applied to the semiconductor laser device. 9, parts corresponding to those in FIG. 1 are designated by the same reference numerals, and duplicate description will be omitted. Even in this case, it is possible to obtain a surface emitting laser having a lowered threshold value.

Next, another example of the present invention will be described in detail with reference to FIG. In this case, the edge portion 7E of the growth blocking layer 7 on the base side is shown in the cavity length direction, that is, the arrow C <00.
1> Provided so as to extend in the crystal axis direction and project in the <010> crystal axis direction indicated by arrow A. An example of this manufacturing method will be described with reference to FIGS. 2 and 10A-
In C, parts corresponding to those in FIGS. 1 and 8A to 8C are denoted by the same reference numerals, and duplicate description will be omitted.

First, as shown in FIG. 10A, the semiconductor substrate 1
After forming the respective layers 2 to 6 and the protective film 15 in the same manner as the example described above in the perspective view of FIG. 1 and the process diagrams of FIGS. 8A to 8C, as shown in FIG. 10B, SiO ₂ , Si ₃
The growth stop layer 7 made of a dielectric material such as N ₄ is patterned so that the edge portion 7E on the base side projects in the cavity length direction as described above. Then, when the second-conductivity-type crystal growth layer 8 is epitaxially grown thereafter, no growth occurs on the growth blocking layer 7, and the growth layer 8 is formed extending from the edge portion 7E of the growth blocking layer 7. In this case, the growth layer 8 is also formed on the second conduction type clad layer 6 so as to extend from the inner edge of the top of the growth blocking layer 7.

In this case, the reflecting mirror surfaces 12A and 12B which are 45 ° in crystal growth with the substrate 1 are formed farther from the growth blocking layer 7 than in the example of FIG. The laser light reflected by the reflecting mirror surfaces 12A and 12B in the direction perpendicular to the substrate 1 can efficiently emit surface light without vignetting due to the growth blocking layer 7.

Also in this case, the reflecting mirror surface 12A
And 12B are formed by crystal growth, have good flatness and angle controllability, and their growth conditions are almost the same as those of ordinary semiconductor lasers. Therefore, the surface emitting semiconductor laser is excellent in versatility and simplicity. The device can be obtained.

In the example described with reference to FIGS. 1 and 2, the growth stop layer 7 has a thickness of λ / λ with respect to the wavelength λ of the laser light in order to efficiently emit the laser light to the outside.
It is desirable to select around 2.

Further, in the above-mentioned respective examples, when laser light is emitted from both end faces of the resonator to obtain a laser of two light fluxes, the resonator length, the thickness of the growth blocking layer 7, the length of the edge portion 7E, etc. are appropriate. By selecting, the interval of each laser beam can be arbitrarily formed with good controllability.

Further, in these examples, as described above, the crystal growth layer 8 on the active layer 3 has the reflecting mirror surfaces 12A and 1A.
Similarly to the growth layer 8 forming 2B, the growth is performed while forming a {110} crystal plane forming 45 ° with the substrate 1. By utilizing this, as shown in FIG. 11, for example, the active layer extends in the <010> crystal axis direction parallel to the main surface of the semiconductor substrate 1 and the height of the active layer is higher than that of the active layer 3 described above. By forming the formed semiconductor laser (not shown) on the same substrate, a laser beam with two light fluxes is obtained as shown by arrows La and Lb, and emitted light from other semiconductor lasers formed on both sides of the laser beam is obtained. By emitting Lc and Ld in the vertical direction on the reflecting mirror surfaces 12C and 12D on the active layer 3 described above, a four-beam multi-beam surface emitting semiconductor laser can be obtained.

Next, another example of the present invention will be described in detail with reference to FIG. In FIG. 3, parts corresponding to those in FIG. 1 are designated by the same reference numerals, and redundant description will be omitted.

In this case, as the semiconductor substrate 1, {10
Using an off-substrate tilted by about 9.7 ° from the <0-11> crystal plane to the <0-11> crystal axis direction, the cavity length direction is set to 90 ° with the {100} crystal plane from the <0-11> crystal axis direction. Make up <10
0> It can be formed by selecting a direction inclined by about 9.7 ° with respect to the crystal axis direction and having, for example, the same material composition and constitution as the example shown in FIG. In this case, as the reflecting mirror surfaces 12A and 12B, similarly, crystal growth {11
For example, the (11-1) crystal plane and the (1-1) crystal plane of the 1} B crystal plane
1) It is grown and formed as a crystal plane. The {111} B crystal plane forms an angle of approximately 54.7 ° with respect to the {100} crystal plane, and in this case, an off-substrate that forms an angle of 9.7 ° with respect to the {100} crystal plane is used. , The reflecting mirror surfaces 12A and 12B are approximately 45 with respect to the main surface 1S of the substrate 1, respectively.
° It can be installed so that

Therefore, also in this case, the laser oscillation is generated by the injection of the current, and the light once emitted parallel to the main surface 1S of the substrate 1 is reflected by the reflecting mirror surfaces 12A and 12B forming 45 ° with respect to the substrate 1. Surface emission can be realized by reflecting the light in a direction perpendicular to the substrate 1.

Next, another example of the present invention will be described in detail with reference to FIG. In this example, the case where the present invention is applied to the semiconductor laser having the SDH type structure described in FIG. 12 is shown.

In this case, from the {100} crystal plane, <0-1
1> Extending from the <011> crystal axis direction to the <100> crystal axis direction by 9.7 ° on the main surface 1S of the substrate 1 made of an off substrate tilted by about 9.7 degrees in the crystal axis direction. Ridge 22 is provided, and a first conduction type clad layer 2 made of n-type AlGaAs, an active layer 3 made of intrinsic GaAs, and a second conduction type clad layer 4 made of p-type AlGaAs are sequentially formed on the ridge 22. For example, it is deposited by MOCVD. At this time, once the {111} B crystal plane is formed along the edge of the ridge 22, epitaxial growth is unlikely to occur on this plane, so that the layers 2, 3 and 4 are formed on the ridge 22 and in the grooves on both sides. It is possible to obtain a low threshold semiconductor laser in which the lateral end face of the active layer 3 is formed by being divided into slopes composed of {111} B crystal planes, and the lateral end faces of the active layer 3 are buried by the cladding layer 4. .

In this case, as shown in FIG. 4, the cavity facets 11A and 11B are formed by vertical etching such as RIE with a predetermined cavity length L _c , and the cavity length direction, that is, arrow F indicates <. 011> One side surface 11C along the crystal axis direction, and both end surfaces 11A and 11B
Similarly, the first reflecting mirror surface 18 forming an angle of 45 ° is formed by vertical etching, and anisotropic etching such as RIE is applied by applying photolithography or the like so that the upper surface of the first reflecting mirror surface 18 becomes a substantially M-shaped pattern. Patterning is formed.

Furthermore, similarly to the above-mentioned examples of FIGS. 1 and 3, a growth blocking layer 7 made of SiO ₂ , Si ₃ N ₄ or the like is further formed thereon.
Are formed by overall surface deposition, anisotropic etching, selective etching, or the like. At this time, the growth stop layer 7 is deposited on the resonator end faces 11A and 11B, the side face 11C, and the first reflecting mirror surface 18, and at the same time, the resonator end faces 11A and 11B.
And the first reflecting mirror surface 18 and the main surface 1S of the substrate 1
Patterning is performed so that it is also deposited on the bottom surface parallel to the substrate 1. The growth blocking layer 7 exposes the crystal plane extending in the <011> crystal axis direction indicated by arrow F on the substrate 1.

After that, a second layer made of p-type GaAs or the like is used.
The conduction type crystal growth layer 8 is again epitaxially grown by the MOCVD method or the MBE method. Also in this case, once the {111} B crystal plane is formed along the growth inhibition layer 7 extending along the <011> crystal axis direction, epitaxial growth is unlikely to occur on this plane.
The second reflecting mirror surface 19 of the 11} B crystal plane, which is the (1-11) crystal plane in this case, is spontaneously formed along the resonator side surface 11C so as to face the first reflecting mirror surface 18. It Also in this case, the substrate 1 is {100}
Since the off substrate tilted by 9.7 degrees from the crystal plane in the <0-11> crystal axis direction is used, the second reflecting mirror surface 19 composed of the {111} B crystal plane is formed on the main surface 1S of the substrate 1. It is formed to form an angle of 45 degrees.

In such a structure, although not shown, an electrode for ohmic connection is provided in the upper part of the light emitting region sandwiched between the two resonator end faces 11A and 11B and in the rear face of the substrate 1 to supply current thereto. The laser light shown by the arrow L ₁ emitted from the end surface 11A is oscillated by the first reflecting mirror surface 18 and the main surface 1S of the substrate 1
The second reflecting mirror 19 along and taken out in the direction indicated by the arrow L ₂ constituting the resonator length direction and 45 °, forming a further 45 ° the light to the main surface 1S of the substrate 1 are shown by arrows L _O Thus, the surface emitting laser can be obtained by taking out in the direction perpendicular to the substrate 1.

Next, another example of the present invention will be described in detail with reference to FIG. 5, parts corresponding to those in FIG. 4 are designated by the same reference numerals, and redundant description will be omitted. In this example, the main surface 1S of the semiconductor substrate 1 is composed of {100} crystal faces, the resonator length direction is selected as the <011> crystal axis direction, and the ridge 22 extending in the resonator length direction is formed. A case where an SDH type low threshold semiconductor laser is formed on the lever is shown.

Then, the first reflecting mirror surface 18 is formed to form an angle of approximately 22.5 ° from the resonator length direction, that is, the angle α formed with one resonator end surface 11A is set to 67.5 °, and this resonator end surface is formed. 11A and 11B are simultaneously formed by vertical etching, and at the same time, a side surface 11C along the cavity length direction is formed by vertical etching along the cavity length direction.

In this case, the end faces 11A and 11B,
While covering the first reflecting mirror surface 18 and the side surface 11C, it is sandwiched between the end surface 11A and the first reflecting mirror surface 18, and is covered with Si ₃ N ₄ , SiO ₂ or the like so as to cover a part of the bottom surface portion along the main surface 1S. The growth preventing layer 7 is formed, and in particular, patterning is performed so that one edge portion 7S thereof is along the <001> crystal axis direction indicated by the arrow F on the bottom surface portion.

In such a structure, when, for example, p-type AlGaAs or the like is epitaxially grown by MOCVD or MBE, the substrate 1 is spontaneously formed along the edge 7S as in the example shown in FIG. The {110} crystal plane forming an angle of 45 ° with respect to the main surface 1S of the above is formed as the second reflecting mirror surface 19, so that the light L ₁ emitted from the resonator end faces 11A and 11B can be converted into the first As shown by an arrow L ₂ by the reflecting surface 18, after being reflected in a direction forming about 22.5 ° from the cavity length direction, by the second reflecting mirror surface 19 forming 45 ° with respect to the main surface 1S of the substrate 1. It can be taken out in a direction perpendicular to the substrate 1 as indicated by an arrow L _O.

In each of these examples, a laser device can be manufactured without cleaving, and laser light free from aberration and vignetting can be taken out in a direction perpendicular to the surface of the substrate. Therefore, the characteristics of the laser can be measured before the substrate is divided into each element, and the inspection time and the mounting cost can be reduced. Further, the shape of the element can be reduced. That is, the shape of about 300 × 300 μm ² was obtained by cleavage, but in the present invention, the minimum per element is 10 × 10.
It is possible to obtain a high-density two-dimensionally integrated surface-emitting laser because it can be formed in a minute shape of about μm ² .

In the semiconductor laser device according to each of the above-mentioned examples, an optical output of 10 mW or more per element can be obtained, a large output can be obtained as compared with the vertical cavity surface emitting laser, and the cleavage can be achieved. It was possible to obtain the same optical output-current characteristics as the semiconductor laser device formed by.

It is needless to say that the present invention is not limited to the constitution described in each of the above-mentioned embodiments, and various other material constitutions can be adopted. For example, the composition of each layer is the above-mentioned AlGaAs / GaAs. Of course, the present invention can be applied to various semiconductor laser devices such as a visible light type InAlGaP / InGaP / GaAs system and a long wavelength type InGaAsP / InP type material.

[0075]

As described above, according to the present invention, since the crystal growth reflecting mirror surface is used, it is possible to obtain the same optical output-current characteristic as that of the semiconductor laser device formed by cleavage, and the reflecting mirror surface Since the angle controllability is excellent, it is possible to take out laser light without aberration and vignetting in a direction perpendicular to the semiconductor substrate accurately. According to the present invention as described above, the semiconductor laser device can be two-dimensionally integrated.

Further, since the semiconductor laser device of the present invention can be formed under normal growth conditions without, for example, high temperature growth, it is extremely advantageous in versatility and simplicity.

Further, in particular, the semiconductor laser has a SAN type structure, a Rib type structure, or an extension direction of the cavity length,
A low threshold surface emitting laser device can be obtained by appropriately selecting growth conditions and the like to form an SDH type structure.

[Brief description of drawings]

FIG. 1 is an enlarged schematic perspective view of an example of a semiconductor laser device of the present invention.

FIG. 2 is an enlarged schematic perspective view of another example of the semiconductor laser device of the present invention.

FIG. 3 is an enlarged schematic perspective view of another example of the semiconductor laser device of the present invention.

FIG. 4 is an enlarged schematic perspective view of another example of the semiconductor laser device of the present invention.

FIG. 5 is an enlarged schematic perspective view of another example of the semiconductor laser device of the present invention.

FIG. 6 is an explanatory diagram of a growth mode of a reflecting mirror surface.

FIG. 7 is a manufacturing process diagram of an example of a semiconductor laser device of the present invention.

FIG. 8 is a manufacturing process diagram of an example of a semiconductor laser device of the present invention.

FIG. 9 is an enlarged schematic perspective view of another example of the semiconductor laser device of the present invention.

FIG. 10 is a manufacturing process diagram of another example of the semiconductor laser device of the present invention.

FIG. 11 is a schematic enlarged perspective view of another example of the semiconductor laser device of the present invention.

FIG. 12 is an enlarged schematic perspective view of an example of a conventional semiconductor laser device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Semiconductor substrate 2 1st conduction type clad layer 3 Active layer 4 2nd conduction type clad layer 5 Current blocking layer 6 2nd conduction type cladding layer 7 Growth inhibition layer 8 2nd conduction type crystal growth layer 9 Electrode 10 High reflection film 11A Resonator end surface 11B Resonator end surface 12A Reflective mirror surface 12B Reflective mirror surface 15 Protective film 18 First reflective mirror surface 19 Second reflective mirror surface

Front page continuation (72) Inventor Yoshifumi Mori 6-735 Kitashinagawa, Shinagawa-ku, Tokyo Sony Corporation

Claims (9)

[Claims] 1. A semiconductor substrate having at least a first-conductivity-type cladding layer, an active layer, and a second-conductivity-type cladding layer, and facing a cavity end face formed by vertical etching. The semiconductor laser device is characterized in that the crystal growth surface forming an angle of about 45 ° with the main surface of the semiconductor substrate is a reflecting mirror surface. 2. The main surface of the semiconductor substrate is composed of a {100} crystal plane, the cavity length direction is selected to be the <010> crystal axis direction, and the crystal growth {110} crystal surface is a reflection mirror surface. The semiconductor laser device according to claim 1, wherein: 3. The reflecting mirror surface composed of the {110} crystal plane is grown from an edge portion of a growth blocking layer for preventing crystal growth formed on the main surface composed of the {100} crystal surface of the semiconductor substrate. It is a crystal plane, and the edge portion of the growth inhibiting layer is <0.
The semiconductor laser device according to claim 2, wherein the semiconductor laser device is formed so as to extend in the <01> crystal axis direction and project in the <010> crystal axis direction. 4. The semiconductor substrate comprises an off-substrate tilted from the {100} crystal plane in the <0-11> crystal axis direction by about 9.7 °, and the cavity length direction is from the <0-11> crystal axis direction. 2. The semiconductor laser device according to claim 1, wherein the crystal growth {111} B crystal plane is selected as a direction inclined by about 9.7 [deg.] With respect to the <100> crystal axis direction and is a reflecting mirror surface. 5. A semiconductor substrate having at least a first-conductivity-type cladding layer, an active layer, and a second-conductivity-type cladding layer, which is emitted from a cavity end facet formed by vertical etching. Has a first reflecting mirror surface formed by vertical etching for extracting the laser light in a direction along the main surface of the semiconductor substrate, and reflecting light from the first reflecting mirror surface to the main surface of the semiconductor substrate. Second, consisting of crystal growth planes taken out in the vertical direction
A semiconductor laser device having a reflecting mirror surface of. 6. The semiconductor substrate is an off-substrate tilted from the {100} crystal plane in the <0-11> crystal axis direction by about 9.7 °, and the first reflecting mirror surface is approximately 45 from the cavity length direction. 5. The semiconductor laser device according to claim 4, wherein the crystal growth {111} B crystal plane is provided as a second reflection mirror surface. 7. The semiconductor laser device according to claim 5, wherein a ridge extending in the <011> crystal axis direction is provided on the semiconductor substrate. 8. The main surface of the semiconductor substrate is composed of a {100} crystal plane, and the first reflecting mirror surface is approximately 22.5 ° from the cavity length direction.
5. The semiconductor laser device according to claim 4, wherein the crystal growth {110} crystal plane serves as the second reflecting mirror surface. 9. The semiconductor laser device according to claim 7, wherein a ridge extending in the <011> crystal axis direction is provided on the semiconductor substrate.