JP2000294877A - High output semiconductor laser and manufacture of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor laser applicable to a rewritable optical disk necessitating a laser light source with a high light output, and increased in a kink light output, and decreased in operating currents by keeping heating due to injecting currents low at the time of laser oscillation, and a method for manufacturing this semiconductor laser. SOLUTION: A mesa 112 is formed under the condition of a proper etching gas pressure and a proper substrate temperature by dry etching so that a double heterostructure constituted of at least an active layer 104 and clad layers 103 and 107 interposing this active layer 104 cam be formed on a substrate 102 constituted of a zincblende type compound semiconductor whose substrate facial azimuth is inclined from 001. Also, mesa-shaped stripes for operating light closure to a horizontal direction are formed, and the cross section shapes vertical to the stripe directions of the mesa are made symmetrical when viewed with the substrate below so that a semiconductor laser without any sagging at the mesa fringe can be manufactured.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor laser used as a light source required for a pickup of an optical disk device, other electronic devices, information processing devices, and the like, and a method of manufacturing the same.

[0002]

2. Description of the Related Art The following two examples of fabricating a semiconductor laser by forming a mesa by dry etching on a substrate inclined in the [110] direction from a (001) plane are shown below.
The present invention relates to an aInP red semiconductor laser.

The first example is a prototype produced by Tada et al., Which is described in Electronics Letters, Vol. 30, page 2035. FIG. 7 shows a cross-sectional structure diagram thereof. In this example, the GaAs substrate is manufactured using a GaAs substrate whose plane orientation is inclined by 6 ° in the [110] direction from the (001) plane. By removing the damaged layer by wet etching after dry etching, operation reliability equivalent to that obtained by forming a mesa only by wet etching is obtained. Also, as compared to the case of only wet etching, a mesa shape that is nearly symmetrical is realized, but since the wet etching is performed after the dry etching, the shape is slightly trapezoidal, and a droop is seen at the mesa bottom.

[0004] A second example is Kidoguchi et al., Japanese Journal of Applied Physics 36
Vol. 1892, and its cross-sectional structure is shown in FIG. In the example, the substrate plane orientation is from the (001) plane,
It is manufactured using a GaAs substrate inclined in the [110] direction, but the substrate plane orientation is not specified. By removing the damaged layer by wet etching after dry etching, operation reliability at an optical output of 25 mW is obtained. Although a symmetrical mesa shape is also realized, since the wet etching is performed after the dry etching, the shape is slightly trapezoidal, and a droop is seen at the mesa hem.

Further, Tada et al. Previously produced a prototype laser having a structure as shown in FIG. 9B and presented it at the 58th Annual Conference of the Japan Society of Applied Physics (4a-Zc-6). In this example, the plane orientation is (115) A (1 in the [110] direction from the (001) plane.
A mesa is formed by wet etching using a GaAs substrate having a tilt of 5.8 °, thereby realizing operation reliability at a temperature of 70 ° C and an optical output of 30 mW. Plane orientation (115) A compared to plane orientation (001)
(15.8 ° tilt from (001) plane to [110] direction)
The advantages of using the GaAs substrate are that the threshold current value can be reduced by suppressing the step bunching, and that the oscillation wavelength can be easily shortened by the natural superlattice disorder.

Further, an InP-based semiconductor laser, AlGaAs
In s-based lasers, there are many examples of mesa formation using dry etching.
No. 106704 discloses an example of an embedded hetero type,
For the s system, an example of a ridge stripe type is disclosed in JP-A-4-127764. In these systems, a tilted substrate is usually rarely used, and the plane orientation is (00).
This is because the above-mentioned problems of step bunching and natural superlattice do not become noticeable even when the substrate 1) is used.

Incidentally, some InP-based semiconductor lasers include (0
In some cases, a substrate inclined about 2 ° from the (01) plane is used, but these are all in the stripe direction [−11].
0] direction.

[0008]

The problem is that the kink light output of the semiconductor laser is reduced. When the kink light output is reduced, it cannot be applied to a rewritable optical disk or the like that requires a laser light source having a high light output.

The reason why the kink light output decreases is that the waveguide strike
The mesa shape in the cross section perpendicular to the
That is, it is asymmetrical when viewed. Or
Even if left-right symmetric, the mesa side surface orientation and substrate orientation
The angle to be formed is less than 80 °, or there is nobody in the mesa hem
Then, the kink light output decreases. Usually, the mesa formation is made of SiO _Two
Using a film or the like as a mask, semiconductors are
This is done by etching, but it is often
In this case, the chemically stable (111) plane is the side surface.

Therefore, the plane orientation changes from (001) to [1].
When a mesa is formed by wet etching to provide a stripe oriented in the [−110] direction on a tilted substrate inclined in the [10] direction, the size of the angle formed between the substrate surface and the mesa side surface differs between the left and right sides. It will be. Also, at this time, the side of the mesa having a shallower angle tends to have a wavy shape like a tail of the mesa. The tendency described above increases as the substrate tilt accuracy increases. In particular, when the inclination angle is 1
When the angle is 5 ° or more, the problems of the asymmetry of the mesa shape and the drooping of the mesa foot become remarkable, and both cause the kink light output of the semiconductor laser to decrease.

In particular, a buried hetero semiconductor laser
Since the active layer is included in the mesa, the etching depth at the time of forming the mesa is large and the difference between the upper bottom and the lower bottom of the trapezoidal mesa is larger than that of the ridge stripe type laser. Therefore, when the wet etching method is applied to the formation of a mesa of a buried hetero semiconductor laser, there is a problem that the above-described kink light output is low even when the substrate tilt angle is small as compared with the ridge stripe type.

Another problem is that, when the cross-sectional shape of the mesa when the substrate is viewed downward is a trapezoidal shape in which the upper base is smaller than the lower base, the electric resistance near the upper base becomes large, and the current injection As a result, heat generation at the time increases, so that a laser operation current value at a high temperature increases. This tendency becomes more remarkable as the etching depth increases. This is also inconvenient for application to an optical disc.

The present invention has been made in view of the above circumstances, and has as its object to provide a semiconductor laser having a high kink light output which can be applied to a rewritable optical disk or the like which requires a laser light source having a high light output. And a method of manufacturing the same. It is another object of the present invention to provide a semiconductor laser having a low operating current by suppressing heat generation due to an injection current at the time of laser oscillation, and a method of manufacturing the same.

[0014]

A semiconductor laser according to the present invention comprises at least an active layer and an active layer formed on a substrate made of a zinc blende type compound semiconductor and having a substrate orientation inclined from (001) to [110]. A double-hetero structure composed of sandwiched cladding layers, a mesa-shaped stripe for horizontally and horizontally confining light, the stripe being oriented in the [-110] direction, and the mesa stripe being The cross-sectional shape perpendicular to the direction is symmetrical when viewed with the substrate facing down, and there is no droop at the mesa hem.

Further, another semiconductor laser according to the present invention comprises a zinc blende type compound semiconductor and has a substrate plane orientation of (001).
From the plane in the [110] direction by more than 15 degrees,
(11n) On a substrate in the A (1 ≦ n ≦ 5) direction, the substrate has a double hetero structure composed of at least an active layer and a clad layer sandwiching the active layer, and has a mesa-like shape for performing horizontal and horizontal light confinement. It has a stripe, and the stripe is oriented in the [-110] direction, and the cross-sectional shape of the mesa perpendicular to the stripe direction is symmetrical when viewed with the substrate facing down, and the mesa has a wavy shape. The feature is that there is no.

Further, another semiconductor laser according to the present invention is characterized in that, in addition to the above features, the angle formed by the plane orientation of the mesa side surface and the substrate plane orientation is 80 ° or more.

According to another aspect of the present invention, there is provided a semiconductor laser having any one of the above-mentioned features, wherein the active layer or the cladding layer is a GaInP layer, an AlGaInP layer, or a GaInP layer.
And a quantum well layer made of AlGaInP.

In the method of manufacturing a semiconductor laser according to the present invention, when a mesa is formed by etching an AlGaInP semiconductor by a dry etching method, the substrate temperature is set at 150 ° C.
C. or higher, and the etching gas pressure is set to 1 × 10 ⁻⁴ torr or more and 5 × 10 ⁻³ torr or less.

Generally, the kink light output is larger when the width of the waveguide stripe is smaller. This is because, when the width of the waveguide stripe is small, the influence of a higher-order mode in the horizontal and horizontal directions, which is a cause of kink, can be suppressed.

FIG. 13 is a graph showing the relationship between the stripe width and the kink light output of ridge stripe type semiconductor lasers having various mesa shapes. 1301, 1
The curves 302, 1303 and 1304 are respectively shown in FIG.
This is a semiconductor laser having the structure shown in FIGS. 10, 9A and 9B. FIG. 1 shows that the substrate plane orientation is from the (001) plane.
The present invention has a symmetric rectangular mesa formed by mesa formation by dry etching to provide a stripe oriented in the [-110] direction on a (115) plane orientation substrate inclined at 15.8 ° in the [110] direction. FIG. 10 shows a structure having a symmetric trapezoidal mesa in which a mesa is formed by wet etching to provide a stripe oriented in the [−110] direction on a substrate having a substrate orientation of (001).
FIG. 9A shows that the substrate plane orientation is [11] from the (001) plane.
A structure having an asymmetric trapezoidal mesa in which a mesa is formed by wet etching in order to provide a stripe oriented in the [−110] direction on a substrate inclined by 10 ° to the [0] direction, FIG. Is [1] from the (001) plane.
[-110] on a substrate inclined at 15.8 ° in the [10] direction
9A is a structure having an asymmetric trapezoidal mesa in which a mesa is formed by wet etching in order to provide an oriented stripe. The structure of FIG. 9B has a greater asymmetry than the structure of FIG. 9A.

The stripe width in this case is the width of the mesa bottom as shown in each figure. Each structure has a thickness of about 1.5 μm for both p and n cladding layers, and the active layers are GaInP and A
It has a quadrupole well structure made of lGaInP, and the thickness of the well layer and the amount of lattice distortion are adjusted so that the oscillation wavelength becomes about 660 nm. As can be seen from the graph, the kink light output is 13
01, 1302, 1303, and 1304. The degree of the kink light output decrease due to asymmetry is 1303.
It can be seen that the tendency is larger at 1304 than at 1304, and the tendency becomes stronger when the inclination angle is 15 ° or more.

FIG. 15 shows operating current values when the optical output during continuous oscillation of the semiconductor laser having each structure is 30 mW. As can be seen from the table, the operating current value is 130
1 is the smallest. This is because the width of the upper part of the mesa is wide,
This is because the electric resistance is reduced, and heat generation during current injection is suppressed.

Next, FIG. 14 is a graph showing the relationship between the stripe width and the kink light output of the buried hetero semiconductor laser having various mesa shapes. 1401,
The curves 1402 and 1403 correspond to FIGS.
1. Semiconductor laser having the structure of FIG. FIG. 3 shows that the substrate orientation is 1 in the [110] direction from the (001) plane.
[−11] on a (115) plane substrate inclined at 5.8 °
0] structure of the present invention having a symmetrical rectangular mesa formed by dry etching to provide a stripe oriented in the direction [0]. FIG.
A structure having a symmetric trapezoidal mesa in which a mesa is formed by wet etching in order to provide a stripe oriented in the [−110] direction on a substrate having a substrate orientation of FIG. In order to provide a stripe oriented in the [−110] direction on a substrate inclined by 10 ° to the [] direction, the substrate has an asymmetric trapezoidal mesa in which a mesa is formed by wet etching. An asymmetric trapezoidal mesa formed by mesa formation by wet etching in order to provide a stripe oriented in the [−110] direction on a substrate whose substrate plane orientation is inclined 15.8 ° in the [110] direction from the (001) plane. Cannot be manufactured for the reason described in the section of the embodiment.

The stripe width in this case is the width of the active layer as shown in each figure. Each structure has a thickness of about 1.5 μm for both p and n cladding layers, and the active layers are GaInP and A
It has a quadrupole well structure made of lGaInP, and the thickness of the well layer and the amount of lattice distortion are adjusted so that the oscillation wavelength becomes about 660 nm. As can be seen from the graph, the kink light output is 14
01, 1402, and 1403 in that order. Further, the degree of the kink light output decrease due to asymmetry is large at 1403, and it can be seen that the tendency becomes stronger when the inclination angle is 10 ° or more.

Next, FIG. 16 shows the operating current values when the optical output during continuous oscillation of the semiconductor laser having each structure is 30 mW. As can be seen from the table, the operating current value is 140
1 is the smallest. This is because the width of the upper part of the mesa is wide,
This is because the electric resistance is reduced, and heat generation during current injection is suppressed.

As described above, it is understood that the kink light output of the semiconductor laser can be increased and the operating current value can be reduced by forming the rectangular symmetric mesa by using the dry etching. The rectangular symmetric mesa structure is particularly effective in an AlGaInP red semiconductor laser used as a light source for an optical disk. This is because the semiconductor laser has a low kink light output and a large increase in operating current due to heat generation, as compared with an AlGaAs-based semiconductor laser used as an excitation light source for optical fiber communication or the like.

[0027]

Next, embodiments of the present invention will be described with reference to the drawings. FIG. 4 is a cross-sectional view of a manufacturing process of the ridge stripe type semiconductor laser according to the present invention as viewed from a direction perpendicular to the waveguide stripe.

First, vapor-phase organometallic crystal growth (MOVP
By the method E), the substrate orientation is changed from the (001) plane to [11].
0] direction n-type GaAs substrate 102 inclined at 15.8 °
On top, an n-type (Al _0.7 Ga _0.3 ) _0.5 In _0.5 P cladding layer 103 (1.5 μm in thickness), GaInP (7 nm in thickness)
And quadrupole well active layer 104 of (Al _0.7 Ga _0.3 ) _0.5 In _0.5 P (4 nm thick), p-type (Al _0.7 G
a _0.3 ) _0.5 In _0.5 P clad layer 107 (1.5 μm thick)
m), p-type GaInP hetero buffer layer 108 (thickness: 20 n)
m), p-type GaAs cap layer 109 (0.3 μm thick)
m), and then a SiO ₂ film is formed on the entire surface of the substrate by a thermal CVD method.
3.5 μm wide SiO facing the [-110] direction
_Two stripes 113 are formed (a).

Then, using the SiO ₂ stripe 113 as a mask, an active layer 1 is formed by chlorine plasma at a substrate temperature of 200 ° C. and a gas pressure of 5 × 10 ^-4 torr using a RIBE apparatus.
The semiconductor is dry-etched to a depth of 0.3 μm above 04 to form a mesa (b).

Next, the n-type AlIn is selectively formed on the mesa side by MOVPE using the SiO ₂ stripe 113 as a mask.
P block layer 105 (thickness 0.3 μm), n-type GaAs
It is buried with the block layer 106 (0.5 μm in thickness) (c).

Next, the SiO ₂ stripes 113 are removed with buffered hydrofluoric acid, and a p-type GaAs contact layer 110 is again laminated on the entire surface of the substrate by the MOVPE method. Then, the p-side electrode 111 and the n-side electrode 101 are formed by a vapor deposition method. (D).

Finally, the laser substrate is set to a width of 300 μm and a resonator length of 600 μm so that the waveguide stripe is the center line.
Cleavage into the individual chips of m completes the structure shown in FIG.

When the characteristics of the semiconductor laser fabricated in this manner were evaluated, the kink light output was 50 mW when the stripe width was 3.5 μm, and the operating current value during continuous oscillation at 15 mW was 55 mA. By the way, a similar board,
The kink light output of the semiconductor laser having the layer structure and the stripe width and the mesa formation by the wet etching (the structure of FIG. 9) and the operating current value at the time of the continuous oscillation of 15 mW were 30 mW and 60 mA, respectively.

FIG. 5 shows a buried hetero type semiconductor laser according to the present invention.
View the manufacturing process of the laser from the direction perpendicular to the waveguide stripe.
FIG. First, vapor phase metalorganic crystal growth (MO
By the VPE) method, the substrate orientation is changed from the (001) plane to
N-type GaAs substrate 20 inclined at 10 ° in [110] direction
2, an n-type (Al_0.7Ga_0.3)_0.5In_0.5P clad
Layer 203 (thickness 1.5 μm), GaInP (thickness 7 n)
m) and (Al_0.7Ga_0.3) _0.5In_0.5P (4 nm thick)
Quadrupole well active layer 204 made of p-type (Al_{0. 7}G
a_0.3)_0.5In_0.5P cladding layer 207 (thickness 1.5μ)
m), p-type GaInP hetero buffer layer 208 (thickness: 20 n)
m), p-type GaAs cap layer 209 (0.3 μm thick)
m) are laminated, and then the SiO_TwoFilm to substrate
After film formation on the entire surface, by photolithography method
3 μm wide SiO facing the [-110] direction_TwoS
A tripe 213 is formed (a).

Next, using the SiO ₂ stripes 213 as a mask, the active layer 2 is formed by chlorine plasma at a substrate temperature of 200 ° C. and a gas pressure of 5 × 10 ^-4 torr using a RIBE apparatus.
The semiconductor is dry-etched to a depth of 0.3 μm below 04 to form a mesa (b).

Next, the p-type AlIn is selectively formed on the mesa side by MOVPE using the SiO ₂ stripes 213 as a mask.
It is buried with an AlInP block layer 205 (thickness 0.3 μm) and an n-type GaAs block layer 206 (thickness 0.5 μm) each composed of one layer of P and n-type AlInP (c).

Next, the SiO ₂ stripes 213 are removed with buffered hydrofluoric acid, and the p-type GaAs contact layer 210 is again laminated on the entire surface of the substrate by the MOVPE method. (D).

Finally, the laser substrate is set to have a width of 300 μm and a resonator length of 600 μm so that the waveguide stripe is the center line.
Cleavage into the individual chips of m completes the structure shown in FIG.

When the characteristics of the semiconductor laser manufactured in this manner were evaluated, the kink light output was 60 mW when the stripe width was 3 μm, and the operating current value during continuous oscillation of 15 mW was 50 mA. Incidentally, the kink light output of a semiconductor laser (structure of FIG. 12) having the same substrate, layer structure and stripe width and formed by mesa by wet etching, and the operating current value at the time of continuous oscillation of 15 mW are 4 respectively.
0 mW and 60 mA.

FIG. 6 shows a buried hetero type semiconductor laser according to the present invention.
View the manufacturing process of the laser from the direction perpendicular to the waveguide stripe.
FIG. First, vapor phase metalorganic crystal growth (MO
By the VPE) method, the substrate orientation is changed from the (001) plane to
N-type GaAs substrate inclined at 15.8 ° in [110] direction
An n-type (Al_0.7Ga_0.3)_0.5In_0.5P class
Pad layer 303 (thickness 1.5 μm), GaInP (thickness 7
nm) and (Al_0.7Ga_{0 .3})_0.5In_0.5P (4n thickness
m), a quadrupole well active layer 304, p-type (Al
_0.7Ga_0.3)_0.5In_0.5P cladding layer 307 (thickness 1.
5 μm), p-type GaInP hetero buffer layer 308 (thickness 2
0 nm), p-type GaAs cap layer 309 (thickness 0.3).
μm), and then the SiO 2 is deposited by thermal CVD._TwoMembrane based
After forming a film on the entire surface of the plate, by photolithography
3 μm wide SiO facing the [-110] direction_TwoS
A tripe 313 is formed (a).

Next, using the SiO ₂ stripe 313 as a mask, the active layer 3 is formed by chlorine plasma at a substrate temperature of 200 ° C. and a gas pressure of 5 × 10 ^-4 torr using a RIBE apparatus.
The semiconductor is dry-etched to a depth of 0.3 μm below 04 to form a mesa (b).

Next, the p-type AlIn is selectively formed on the side of the mesa by MOVPE using the SiO ₂ stripe 313 as a mask.
It is buried with an AlInP block layer 305 (thickness 0.3 μm) and an n-type GaAs block layer 306 (thickness 0.5 μm) each composed of one layer of P and n-type AlInP (c).

Next, the SiO ₂ stripes 313 are removed with buffered hydrofluoric acid, and the p-type GaAs contact layer 310 is again laminated on the entire surface of the substrate by the MOVPE method. Then, the p-side electrode 311 and the n-side electrode 301 are deposited by the vapor deposition method. (D).

Finally, the laser substrate is set to have a width of 300 μm and a cavity length of 600 μm so that the waveguide stripe is the center line.
Cleavage into the individual chips of m completes the structure shown in FIG.

When the characteristics of the semiconductor laser fabricated in this manner were evaluated, the kink light output was 60 mW when the stripe width was 3 μm, and the operating current value during continuous oscillation of 15 mW was 50 mA. By the way, it was found that when a semiconductor laser having the same layer structure and stripe width was to be formed by forming a mesa by wet etching, the SiO ₂ stripe was lifted off by the side etching of the upper bottom portion of the mesa, and it was impossible to manufacture the semiconductor laser.

[0046]

As described above, according to the present invention, a semiconductor laser having a high kink light output which can be applied to a rewritable optical disk or the like which requires a laser light source having a high light output can be obtained. Further, according to the present invention, a semiconductor laser having a low operating current can be obtained by suppressing heat generation due to an injection current during laser oscillation.

[Brief description of the drawings]

FIG. 1 is a structural diagram of a first embodiment of the present invention.

FIG. 2 is a structural diagram of a second embodiment of the present invention.

FIG. 3 is a structural diagram of a third embodiment of the present invention.

FIG. 4 is a manufacturing process diagram of the first embodiment of the present invention.

FIG. 5 is a manufacturing process diagram of the second embodiment of the present invention.

FIG. 6 is a manufacturing process diagram of the third embodiment of the present invention.

FIG. 7 is a structural view of a conventional embodiment.

FIG. 8 is a structural diagram of a conventional embodiment.

FIG. 9 is a structural view of a conventional embodiment.

FIG. 10 is a structural view of a conventional embodiment.

FIG. 11 is a structural view of a conventional embodiment.

FIG. 12 is a structural view of a conventional embodiment.

FIG. 13 is a graph comparing the characteristics of the first embodiment of the present invention with those of the conventional embodiment.

FIG. 14 is a graph comparing the characteristics of the second embodiment of the present invention with those of the conventional embodiment.

FIG. 15 is a table in which the characteristics of the first embodiment of the present invention are compared with those of the conventional embodiment.

FIG. 16 is a table comparing characteristics of the second embodiment of the present invention with those of the conventional embodiment.

[Explanation of symbols]

101. n-side electrode 102. n-type GaAs substrate 103. n-type AlGaInP cladding layer 104.4 quantum well active layer 105. n-type AlInP block layer 106. n-type GaAs block layer 107. p-type AlGaInP cladding layer 108. p-type GaInP hetero buffer layer 109. p-type GaAs cap layer 110. p-type GaAs contact layer 111. p-side electrode 112. Mesa 113. SiO ₂ stripe 201. n-side electrode 202. n-type GaAs substrate 203. n-type AlGaInP cladding layer 204.4 quantum well active layer 205. AlInP block layer 206. n-type GaAs block layer 207. p-type AlGaInP cladding layer 208. 209. p-type GaInP hetero buffer layer p-type GaAs cap layer 210. p-type GaAs contact layer 211. p-side electrode 213. SiO ₂ stripe 301. n-side electrode 302. n-type GaAs substrate 303. n-type AlGaInP cladding layer 304.4 quantum well active layer 305. AlInP block layer 306. n-type GaAs block layer 307. p-type AlGaInP cladding layer 308. p-type GaInP hetero buffer layer 309. p-type GaAs cap layer 310. p-type GaAs contact layer 311. p-side electrode 312. Mesa 313. SiO ₂ stripe

Claims (17)

[Claims] 1. A double hetero structure comprising at least an active layer and a clad layer sandwiching the active layer on a substrate made of a zinc blende compound semiconductor and having a substrate plane orientation inclined from the (001) direction to the [110] direction. And a mesa-shaped stripe for horizontal and horizontal light confinement, wherein the stripe is oriented in the [-110] direction, and a cross-sectional shape of the mesa is perpendicular to the stripe direction with the substrate facing down. A ridge stripe type semiconductor laser characterized by being symmetrical when viewed from the side, and having no droop at the mesa bottom. 2. A substrate made of a zinc-blende compound semiconductor, in which the orientation of the substrate is inclined by 15 ° or more from the (001) plane to the [110] direction, or in the (11n) A (1 ≦ n ≦ 5) direction. A substrate has a double hetero structure including at least an active layer and a cladding layer sandwiching the active layer, and has a mesa-shaped stripe for confining light in a horizontal lateral direction, and the stripe has a [-110] direction. And a ridge stripe type semiconductor laser characterized in that the cross-sectional shape perpendicular to the stripe direction of the mesa is bilaterally symmetric when viewed with the substrate facing down, and there is no droop at the mesa bottom. 3. The semiconductor laser according to claim 1, wherein the angle between the plane direction of the mesa side surface and the plane direction of the substrate is 80 ° or more. 4. The semiconductor laser according to claim 2, wherein the angle between the plane direction of the mesa side surface and the plane direction of the substrate is 80 ° or more. 5. A double hetero structure comprising at least an active layer and a clad layer sandwiching the active layer on a substrate made of a zinc blende type compound semiconductor and having a substrate plane orientation inclined from the (001) direction to the [110] direction. And a mesa-shaped stripe for horizontal and horizontal light confinement, wherein the stripe is oriented in the [-110] direction, and a cross-sectional shape of the mesa is perpendicular to the stripe direction with the substrate facing down. A buried hetero type semiconductor laser characterized by being symmetrical when viewed from the side, and having no droop at the mesa tail. 6. A substrate made of a zinc-blende compound semiconductor, in which the orientation of the substrate is inclined at least 15 ° from the (001) direction to the [110] direction, or is in the (11n) A (1 ≦ n ≦ 5) direction. A substrate has a double hetero structure including at least an active layer and a cladding layer sandwiching the active layer, and has a mesa-shaped stripe for confining light in a horizontal lateral direction, and the stripe has a [-110] direction. And a cross section perpendicular to the stripe direction of the mesa is bilaterally symmetric when viewed with the substrate facing down, and there is no droop at the bottom of the mesa. 7. The semiconductor laser according to claim 5, wherein the angle between the plane direction of the mesa side surface and the plane direction of the substrate is 80 ° or more. 8. The semiconductor laser according to claim 6, wherein an angle formed between the plane direction of the mesa side surface and the plane direction of the substrate is 80 ° or more. 9. The method according to claim 1, wherein the active layer or the cladding layer is GaInP.
Layer, AlGaInP layer, or GaInP and AlGaIn
2. A quantum well layer comprising a P quantum well layer.
4. The semiconductor laser according to claim 1. 10. The method according to claim 1, wherein the active layer or the cladding layer is GaInP.
Layer, AlGaInP layer, or GaInP and AlGaIn
3. A quantum well layer comprising a P quantum well layer.
4. The semiconductor laser according to claim 1. 11. An active layer or a cladding layer comprising GaInP
Layer, AlGaInP layer, or GaInP and AlGaIn
4. A quantum well layer comprising P.
4. The semiconductor laser according to claim 1. 12. An active layer or a cladding layer comprising GaInP
Layer, AlGaInP layer, or GaInP and AlGaIn
5. A quantum well layer comprising P.
4. The semiconductor laser according to claim 1. 13. An active layer or a cladding layer comprising GaInP
Layer, AlGaInP layer, or GaInP and AlGaIn
6. A quantum well layer comprising P.
4. The semiconductor laser according to claim 1. 14. An active layer or a cladding layer comprising GaInP
Layer, AlGaInP layer, or GaInP and AlGaIn
7. A quantum well layer comprising a P quantum well layer.
4. The semiconductor laser according to claim 1. 15. An active layer or a cladding layer comprising GaInP
Layer, AlGaInP layer, or GaInP and AlGaIn
8. The semiconductor device according to claim 7, further comprising a quantum well layer made of P.
4. The semiconductor laser according to claim 1. 16. An active layer or a cladding layer comprising GaInP
Layer, AlGaInP layer, or GaInP and AlGaIn
9. A quantum well layer comprising P.
4. The semiconductor laser according to claim 1. 17. A method for manufacturing a semiconductor laser according to claim 1, wherein the mesa is formed by etching an AlGaInP semiconductor by a dry etching method. Gas pressure of 1 × 10 ⁻⁴ torr or more and 5 × 10 ⁻³ torr
A method of manufacturing a semiconductor laser, characterized by the following.