JPH04218993A - Semiconductor laser and its manufacture - Google Patents

Abstract

PURPOSE:To lower the oscillation threshold by making small the astigmatic difference of a semiconductor laser, which is made of material such as A GaInP, and whose lateral mode is controlled. CONSTITUTION:This is equipped, on an n-type GaAs substrate 101, with an n-type A GaInP clad layer 102, an active layer 103, and a p-type A GaInP clad layer 104. Furthermore, thereon, an A InP shut-in layer 106 is formed, which has a stripe-shaped aperture and whose refractive index is smaller than that of the p-type A GaInP clad layer 104. Further, thereon, a p-type A GaAs upper clad layer 109 is made, whose band gap is wider and refractive index is lower than those of the ptype A GaInP clad layer 104.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor laser made of a material such as AlGaInP and having a controlled transverse mode, and a method for manufacturing the same.

0002

2. Description of the Related Art Semiconductor lasers that emit light at a wavelength of visible light of 700 nm or less are attracting attention as light sources for use in optical discs, laser printers, bar code readers, and the like. Among them, GaAs is used as a substrate, and Ga0.
5In0.5P (abbreviated as GaInP in the following explanation) or (AlxGa1-x)0.5In0.5P (abbreviated as AlGaInP in the following explanation) as the active layer, A
A double heterojunction semiconductor laser with a cladding layer of lGaInP or AlyGa1-yAs (abbreviated as AlGaAs in the following explanation) can emit light with the shortest wavelength among III-V group compound semiconductors that are lattice-matched to GaAs. This makes it a promising material for red semiconductor lasers.

FIGS. 14 to 17 show cross-sectional structures of conventional internal stripe type AlGaInP semiconductor lasers in each manufacturing process. First, as shown in FIG. 14, n-type AlGaI is applied to the surface of an n-type GaAs substrate 401.
nP cladding layer 402, GaInP active layer 403, p-type AlGaInP cladding layer 404, p-type GaInP etch stop layer 405, and n-type GaAs block layer 40
6 is sequentially crystal-grown using the MO-VPE method (organic metal vapor phase epitaxy). Next, as shown in FIG. 15, using the SiO2 film 407 having striped openings as a mask, the n-type Ga
For example, the As block layer 406 is made of H2SO4:H2O2:
Etching is performed using a mixed solution of H2O=1:1:10. Next, after removing the SiO2 film 407, p
When the type GaAs cap layer 408 is crystal grown, it becomes as shown in FIG. Finally, a p-type ohmic contact electrode 409 made of Cr/Au is formed on the front surface, and the back surface is polished and etched to make the substrate thinner.
When an n-type ohmic contact electrode 410 made of Ni is formed, a conventional internal stripe type AlGaInP semiconductor laser is completed as shown in FIG.

In this conventional laser, n-type GaAs
The blocking layer 406 plays the role of a current confinement layer. Therefore, this conventional internal stripe type AlGaI
An nP semiconductor laser oscillates at a low threshold.

[0005]

[Problems to be Solved by the Invention] Although the conventional internal stripe type AlGaInP semiconductor laser has current confinement, it is a gain waveguide type for light, so the active layer and There was a problem in that the wavefront of the guided light in the parallel direction was bent, resulting in a large astigmatism difference of about 40 μm. Therefore, when trying to apply a conventional internal stripe type AlGaInP semiconductor laser to optical equipment, the scope of application is limited because a single convex lens cannot collimate the laser beam or focus it on one point. I had left it behind.

In addition, the n-type GaAs block layer 406 and the p-type GaAs cap layer 408 absorb light emitted from the active layer, resulting in a loss for the light waveguided through the active layer, which improves current confinement. p-type AlGaI to
There is also the problem that reducing the thickness of the nP cladding layer increases light absorption and increases the oscillation threshold by this loss, making it difficult to lower the oscillation threshold to 70 mA or less. .

[0007]

SUMMARY OF THE INVENTION The present invention has been made to solve the problems in the conventional internal stripe type AlGaInP semiconductor laser, and has the following structure. (1) It has an n-type AlGaInP cladding layer, an active layer, and a p-type AlGaInP cladding layer on an n-type GaAs substrate, and further has stripe-shaped openings thereon, and has a refractive index higher than that of the p-type AlGaInP cladding layer. AlInP or AlGa with small
It has an InP confinement layer, and the p-type Al
A structure including an upper cladding layer of p-type AlGaAs or AlGaInP, which has a wider band gap and lower refractive index than the GaInP cladding layer. (2) AlI having an n-type AlGaInP cladding layer, an active layer, and a p-type AlGaInP cladding layer on an n-type GaAs substrate, further having striped openings thereon and containing Zn as an impurity.
has an nP or AlGaInP confinement layer, and the A
By diffusion of impurities from the lInP or AlGaInP confinement layer, the AlInP or AlGaInP
A configuration in which the active layer below the confinement layer is disordered. (3) An n-type AlGaInP cladding layer, an active layer, and a p-type AlGaInP cladding layer are formed on an n-type GaAs substrate, and a striped insulating film having striped openings is formed on the n-type AlGaInP cladding layer. An n-type block layer is formed on the outside, and at least the striped openings and the n-type block layer are formed on the outside.
On the type block layer, p-type AlGa has a wider band gap and lower refractive index than the p-type AlGaInP cladding layer.
A structure having an upper cladding layer of As or AlGaInP. (4) a step of forming an n-type AlGaInP cladding layer, an active layer, a p-type AlGaInP cladding layer, and an AlInP confinement layer on an n-type GaAs substrate; a step of forming striped openings in the AlInP confinement layer; The p-type AlGa layer is formed on the AlInP confinement layer and the striped openings.
A configuration including a step of forming a p-type upper cladding layer and a p-type contact layer that have a wider band gap and lower refractive index than the InP cladding layer. (5) An n-type AlGaInP cladding layer, an active layer, a p-type AlGaInP cladding layer, and an A containing Zn as an impurity on an n-type GaAs substrate.
a step of forming an lInP confinement layer, a step of forming striped openings in the AlInP confinement layer, at least the striped openings and the AlInP
forming a p-type upper cladding layer and a p-type contact layer on the confinement layer, and diffusing impurities from the AlInP confinement layer with heat applied at this time to disorder the active layer below the AlInP confinement layer; Configuration with. (6) A step of forming an n-type AlGaInP cladding layer, an active layer, a p-type AlGaInP cladding layer, and an n-type block layer on an n-type GaAs substrate, and a step of forming striped openings in the n-type block layer. , forming a striped insulating film having striped openings on the p-type AlGaInP cladding layer; forming a striped insulation film having striped openings on the p-type AlGaInP cladding layer;
p has a wider bandgap and lower refractive index than the cladding layer.
A configuration comprising a step of forming a mold upper cladding layer and a p-type contact layer.

[0008]

[Operations] The present invention has the following functions and effects due to the structure of the present invention described above.

In configurations (1) and (3), AlInP or AlGaInP confinement layers having a lower refractive index than the p-type AlGaInP cladding layer, or an insulating film are formed on both sides of the stripe, so that the insulating film is formed in the direction parallel to the active layer. It is also possible to confine and guide light, and the refractive index is guided in both directions parallel and perpendicular to the active layer, so the astigmatism difference is also much smaller than in the conventional laser. In addition, since the AlInP or AlGaInP confinement layer or insulating film, which has a lower refractive index than the p-type AlGaInP cladding layer provided on both sides of the stripe, does not absorb the light emitted by the active layer, the loss of light is reduced and the oscillation threshold is is also much smaller than the laser shown in the conventional example.

In structure (2), the natural superlattice existing in the active layer on both sides of the stripe is disordered, the band gap becomes wider, and the refractive index becomes smaller, so light is confined even in the direction parallel to the active layer. Since the laser beam can be guided by the refractive index in both parallel and perpendicular directions to the active layer, the astigmatism difference is also much smaller than in the conventional laser. Furthermore, since the disordered active layers on both sides of the stripe do not absorb the light emitted by the active layer, the loss of light is reduced and the oscillation threshold value is much smaller than that of the conventional laser.

In the manufacturing method of configuration (4), the AlInP confinement layer can be easily selectively etched using the n-type GaAs block layer as a mask, and when crystal-growing the p-type AlGaAs upper cladding layer, Al, which is easily oxidized, is removed. Since the surface of the AlInP optical confinement layer is covered with the n-type GaAs block layer, a crystal with good crystallinity can be grown.

In the manufacturing method of configuration (5), impurities are diffused from the AlInP confinement layer using heat applied when forming the p-type upper cladding layer and the p-type contact layer on the striped opening and the AlInP confinement layer. TeAlI
Since the active layer under the nP confinement layer is disordered, the process is simple and both sides of the opening on the stripe can be automatically disordered.

In the manufacturing method of structure (6), the insulating film is p-type G
Since the aInP etch stop layer is covered from the surface to the side surface of the n-type GaAs block layer, no defects occur even if the p-type AlGaAs upper cladding layer does not grow on top of the insulating film.

[0014]

[Examples] The present invention will be explained below with reference to Examples. 2 to 4 and FIG. 1 show Al of the first embodiment of the present invention.
1A and 1B show schematic cross-sectional structural diagrams in each manufacturing process of a GaInP-based semiconductor laser. First, as shown in FIG. 2, an n-type AlGaInP cladding layer 102 (for example, x=0.6, carrier density 7×1017 cm-3 , thickness 1 μm), GaInP active layer 103 (thickness 0.0 μm, for example)
8 μm), p-type AlGaInP cladding layer 104 (e.g. x=0.6, carrier density 4×10 17 cm −3 , thickness 0.1 μm), p-type GaInP etch stop layer 10
5 (e.g. carrier density 1 x 1018 cm-3, thickness 0
．． 01 μm), p-type AlInP confinement layer 106 (e.g. carrier density 4×1017 cm−3, thickness 0.3 μm)
), n-type GaAs block layer 107 (e.g. carrier density 1 x 1018 cm-3, thickness 0.5 μm) is MO-V
Crystals are successively grown by lattice matching to the n-type GaAs substrate 101 using the PE method. Next, using the SiO2 film 108, which has holes in a stripe shape with a width of 3 μm as a mask, the n-type GaAs
For example, the block layer is H2SO4:H2O2:H2O=1
:1:10 mixture, and further n-type GaA
Using the s-block layer as a mask, the p-type AlInP confinement layer 106 is etched using, for example, hot concentrated sulfuric acid at 30° C. until it reaches the p-type GaInP etch stop layer 104.
As shown in FIG. 3, an opening 51 is formed. In this embodiment, for example, when stripes are formed in the <011> direction, the p-type AlInP confinement layer 106 and the n-type GaAs block layer on both sides of the stripe opening 51 are etched in a forward tapered shape. Next, the SiO2 film 108 is removed and the M
p-type AlGaAs upper cladding layer 1 by O-VPE method
09 (for example, Al composition y=0.7, carrier density 1×1
018 cm-3, thickness 0.5 μm) and p-type GaAs
Cap layer 110 (e.g. carrier density 5×1018c
When crystals are grown over the entire surface, the result is as shown in FIG. 4. Finally, a p-type ohmic contact electrode 111 made of Cr/Au is formed on the front surface, and the back surface is polished and etched to make the substrate thinner.
When forming the n-type ohmic contact electrode 112 made of AlG of the first embodiment of the present invention, as shown in FIG.
The aInP semiconductor laser is completed.

The feature of the first embodiment of the present invention described above is that p-type AlInP confinement layers 106 having a lower refractive index than the p-type AlGaInP cladding layer 102 are formed on both sides of the stripe, so that the active layer It is possible to confine and guide light in the direction parallel to the active layer 103, and therefore the refractive index is guided both in the direction parallel to and perpendicular to the active layer 103, so the astigmatism difference is also smaller than in the laser shown in the conventional example. It is much smaller. For example, in the case of the first embodiment of the present invention, the astigmatism difference was as small as 3 μm. In addition, p-type A provided on both sides of the stripe
p whose refractive index is smaller than that of the lGaInP cladding layer 102.
Since the AlInP confinement layer 106 does not absorb the light emitted by the active layer 103, the loss of light is reduced and the oscillation threshold is much smaller than that of the conventional laser. For example, in the case of the first embodiment of the present invention, the oscillation threshold value was as small as 20 mA. Furthermore, p-type AlI
Since no light is absorbed by the nP confinement layer 106, the stripe width can be narrowed. Therefore, the light emission angle θ| in the direction parallel to the active layer was 8° in the conventional example, but in the present invention it is 11° when the stripe width is 2.5 μm or less.
In the first embodiment of the present invention, the light emission angle θ⊥ in the direction perpendicular to the active layer is 36°, and the aspect ratio θ⊥/θ‖ is 4.5 in the conventional example. What used to be can be reduced to 3.3, making it closer to a circle.

Further, the feature of the manufacturing process of the first embodiment of the present invention described above is that the p-type AlInP confinement layer 106 is
Selective etching can be easily performed using the GaAs block layer 107 as a mask, and when crystal-growing the p-type AlGaAs upper cladding layer 109, the surface of the AlInP optical confinement layer 106 containing easily oxidized Al is formed of n-type GaAs.
Since it is covered with the s-block layer 107, a crystal with good crystallinity can be grown.

It goes without saying that even if the conductivity type of the p-type AlInP confinement layer 106 in the first embodiment of the present invention is changed to n-type, the above characteristics can be obtained in the same manner. Furthermore, it goes without saying that the above characteristics can be similarly obtained even if a p-type or n-type AlGaInP confinement layer having a lower refractive index than the p-type AlGaInP cladding layer 102 is used instead of the p-type AlInP confinement layer 106.

Furthermore, in the first embodiment of the present invention, the n-type GaAs layer above the p-type AlInP confinement layer 106 is
Even if the conductivity type of the block layer 107 is changed to p-type, p-type AlI
The band discontinuity existing in the valence band at the heterojunction between the nP confinement layer 106 and the p-type GaAs block layer acts as a barrier to holes, blocking the flow of current, resulting in the effect of current confinement. Needless to say, can be obtained similarly.

FIGS. 5 to 8 show Al of the second embodiment of the present invention.
1A and 1B show schematic cross-sectional structural diagrams in each manufacturing process of a GaInP-based semiconductor laser. First, as shown in FIG. 5, an n-type AlGaInP cladding layer 202 (for example, x=0.6, carrier density 7×1017 cm-3 , thickness 1 μm), GaInP active layer 203 (thickness 0.0 μm, for example)
8 μm), p-type AlGaInP cladding layer 204 (e.g. x=0.6, carrier density 4×10 17 cm −3 , thickness 0.1 μm), p-type GaInP etch stop layer 20
5 (e.g. carrier density 1 x 1018 cm-3, thickness 0
．． 01 μm), p-type Al doped with Zn as an impurity
InP confinement layer 206 (e.g. carrier density 1×10
18 cm-3, thickness 0.3 μm), n-type GaAs block layer 207 (e.g. carrier density 1×1018 cm-3
, 0.5 μm in thickness) are lattice-matched to the n-type GaAs substrate 201 by the MO-VPE method, and crystals are sequentially grown. Next, a SiO2 film 20 with holes formed in a stripe shape having a width of 3 μm, for example.
8 as a mask, the n-type GaAs block layer is
Etching is performed using a mixed solution of SO4:H2O2:H2O=1:1:10, and then using the n-type GaAs block layer as a mask, the p-type AlInP confinement layer 206 is etched using hot concentrated sulfuric acid at 30° C., for example, to form the p-type GaInP etch stop layer 204. When the etching is performed until reaching this point, an opening 61 is formed as shown in FIG. In this embodiment, for example, if the stripes are formed in the <011> direction, the p-type AlInP confinement layer 206 and the n-type GaA
The s-block layer is etched in a forward tapered shape. Next, the SiO2 film 208 is removed and a p-type AlGaInP upper cladding layer 209 (e.g., Al composition x=0.7, carrier density 5×1017 cm-3, thickness 0.5 μm) and a p-type GaAs cap are formed by MO-VPE. Layer 210 (e.g. carrier density 5 x 1018 cm-3, thickness 3 μm)
When crystals grow over the entire surface, as shown in FIG.
is diffused to disorder the active layer 203 under the AlInP confinement layer 206 to form a disordered layer 220. Finally, a p-type ohmic contact electrode 211 made of Cr/Au is formed on the front surface, and the back surface is polished and etched to make the substrate thinner.
After forming the ohmic contact electrode 212, the AlGaInP semiconductor laser of the second embodiment of the present invention is completed as shown in FIG.

The feature of the second embodiment of the present invention described above is that the disordered layer 220 formed by disordering the natural superlattice existing in the active layer 203 on both sides of the stripe has a wide band gap. At the same time, the refractive index becomes smaller, so light can be confined and guided in the direction parallel to the active layer 203. Therefore, the refractive index is guided both in the direction parallel to the active layer 203 and in the perpendicular direction, so there is no astigmatism difference. It is also much smaller than the laser shown in the conventional example. For example, in the case of the second embodiment of the present invention, the astigmatism difference was as small as 3 μm. In addition, the disordered layer 220 formed by disordering the natural superlattice existing in the active layer 203 on both sides of the stripe has a bandgap of the active layer 203.
Since it is wider than 03 and does not absorb the light emitted by the active layer 203, the loss of light is reduced and the oscillation threshold value is also much smaller than the laser shown in the conventional example. For example, in the case of the second embodiment of the present invention, the oscillation threshold is 2
A small value of 0 mA was obtained. Furthermore, the disordered layer 22
Since there is no absorption of light by zero, the stripe width can be narrowed. Therefore, the light emission angle θ‖ in the direction parallel to the active layer
was 8° in the conventional example, but in the present invention, it can be increased to 11° when the stripe width is 2.5 μm or less, and in the second embodiment of the present invention, the direction perpendicular to the active layer The light radiation angle θ⊥ is 36°, and the aspect ratio θ
⊥/θ‖ was 4.5 in the conventional example, but it has been reduced to 3.3, making it possible to approach a circle.

Further, the features of the manufacturing process of the second embodiment of the present invention described above are that the striped openings 61 and the Al
A p-type upper cladding layer 20 is formed on the InP confinement layer 206.
9 and the p-type contact layer 210 are used to diffuse impurities from the AlInP confinement layer 206 and disorder the active layer 203 under the AlInP confinement layer 206 to form the disordered layer 220, which simplifies the process. Moreover, the disordered layer 220 can be automatically formed on both sides of the opening 61 on the stripe.

Note that in the second embodiment of the present invention, the n-type GaAs layer above the p-type AlInP confinement layer 206
Even if the conductivity type of the block layer 207 is changed to p-type, p-type AlI
In the heterojunction between the nP confinement layer 206 and the p-type GaAs block layer, the band discontinuity that exists in the valence band acts as a barrier to holes, blocking the flow of current, resulting in the effect of current confinement. Needless to say, can be obtained similarly.

FIGS. 9 to 13 show A of the third embodiment of the present invention.
1A and 1B show schematic cross-sectional structural diagrams in each manufacturing process of an lGaInP-based semiconductor laser. First, as shown in FIG.
On the surface of the n-type AlGaInP cladding layer 302 (e.g., x=0.6, carrier density 7×10 17 cm −3 , thickness 1 μm) and GaInP active layer 303 (e.g., thickness 0.6 μm).
08 μm), p-type AlGaInP cladding layer 304 (e.g. x=0.6, carrier density 4×1017 cm-3,
thickness 0.1 μm), p-type GaInP etch stop layer 3
05 (e.g. carrier density 1 x 1018 cm-3, thickness 0.01 μm), n-type GaAs block layer 306 (e.g. carrier density 1 x 1018 cm-3, thickness 0.5 μm)
) is lattice-matched to the n-type GaAs substrate 301 using the MO-VPE method, and crystals are sequentially grown. Next, using the SiO2 film 307 with striped holes with a width of 5 μm as a mask, an n-type GaAs block layer is formed, for example, with H2SO4:H2O2.
:H2O=1:1:10 mixed solution is etched until the p-type GaInP etch stop layer 304 is reached.
As shown in FIG. 10, an opening 71 is formed. In this embodiment, for example, if the stripes are formed in the <011> direction, the n-type GaAs block layer 3 on both sides of the stripe opening 71
06 is etched in a forward tapered shape. Next, SiO2
When the film 307 is removed and a new insulating film, for example, a SiO2 film 308 having a width of 6 μm and having striped openings having a width of 2 μm is formed, the openings 72 are formed as shown in FIG. Ru. Here, SiO2 film 3
The opening 72 of 08 is the p-type GaInP etch stop layer 3.
04. Next, MO-V
A p-type AlGaAs upper cladding layer 309 (
For example, Al composition y=0.7, carrier density 1×1018
cm-3, thickness 0.5 μm) and a p-type GaAs cap layer 310 (e.g. carrier density 5×10 cm-3
, 3 μm thick) on the entire surface as shown in FIG. 12. Depending on the crystal growth conditions, the SiO2 film 308
In some cases, the p-type AlGaAs upper cladding layer 309 or the p-type GaAs cap layer 310 does not grow on the surface of the AlGaAs layer 309 of the third embodiment of the present invention.
It is essentially unrelated to the operation of the InP semiconductor laser. Finally, a p-type ohmic contact electrode 311 made of Cr/Au is formed on the front surface, the back surface is polished and etched to thin the substrate, and an n-type ohmic contact electrode 312 made of Au/Ge/Ni is formed.
As shown in Figure 3, AlGaInP of the third embodiment of the present invention
system semiconductor laser is completed.

The feature of the third embodiment of the present invention described above is structurally that p-type AlGaI is provided on both sides of the stripe.
An insulating film (S
Since the iO2 film 308) is formed, it is possible to confine and guide light in the direction parallel to the active layer, and therefore, the refractive index guides both parallel and perpendicular directions to the active layer. Therefore, the astigmatism difference is also much smaller than that of the conventional laser. Furthermore, the thermal conductivity of the SiO2 film 308 embedded on both sides of the stripe is G
Although the value is lower than that of aAs, in the third embodiment of the present invention, the thickness of the SiO2 film 308 can be made as thin as about 0.1 μm, and the SiO2 film 308 is buried in the openings on both sides of the stripe. 71 and the outside thereof is the n-type GaAs block layer 306. Therefore, the heat generated near the active layer is dissipated by the n-type GaAs block layer 306, and the heat dissipation is not deteriorated by the SiO2 film 308. do not have.

Furthermore, since the SiO2 film 308 has an extremely small light absorption coefficient, light loss is reduced and the oscillation threshold is much smaller than that of the conventional laser. For example, in the case of the third embodiment of the present invention, the oscillation threshold value was as small as 20 mA. Furthermore, SiO2 film 3
Since 08 does not absorb light, the stripe width can be narrowed. Therefore, the light emission angle θ| in the direction parallel to the active layer was 8° in the conventional example, but in the third embodiment of the present invention, it can be increased to 15° when the stripe width is 2 μm. In the case of the third embodiment, the light emission angle θ⊥ in the direction perpendicular to the active layer is 36°, and the aspect ratio θ⊥/θ‖ is 2.4, whereas it was 4.5 in the conventional example.
It can be made smaller and closer to a circle.

The feature of the manufacturing process of the third embodiment of the present invention described above is that the SiO2 film 308 is covered from the surface of the p-type GaInP etch stop layer 305 to the side surface of the n-type GaAs block layer 306. Even if the p-type AlGaAs upper cladding layer 309 does not grow on top of the insulating film, no defects occur.

Furthermore, the third embodiment of the present invention is characterized by a GaAs layer 30 that absorbs light emitted from the active layer in the area outside the SiO2 film 308 provided on both sides of the stripe.
6. In other words, in the lateral mode, which is the distribution of waveguide modes in a plane parallel to the active layer, the higher the mode becomes, the more light leaks out to both sides of the stripe, and the smaller the light confinement coefficient inside the stripe. Become. Therefore, in the semiconductor laser of the third embodiment of the present invention, the higher the lateral mode becomes, the more GaAs
More light is absorbed by layer 306. Therefore, higher-order lateral modes are more likely to be suppressed and oscillation in the fundamental mode is more likely to occur, making it possible to obtain stable operation with less bending of the optical output vs. current characteristics due to mode jumps.

Although GaInP is used as the active layer in the first to third embodiments of the present invention described above, it goes without saying that AlGaInP may also be used. Furthermore, regarding the conductivity type, it goes without saying that the p-type and the n-type may be interchanged.

Furthermore, in the first and third embodiments of the present invention described above, the p-type AlGaAs layer 1 is used as the upper cladding.
I explained the structure using 09 or 309,
Needless to say, the same effect can be achieved even if a p-type AlGaInP layer is used instead. Further, in the second embodiment of the present invention described above, the structure using the p-type AlGaInP layer 209 as the upper cladding was explained, but instead, the p-type AlGaInP layer 209 was used as the upper cladding.
Needless to say, the same effect can be obtained even if an lGaAs layer is used.

[0030]

[Effects of the Invention] As explained above, the present invention has the following effects.

In the structures of the first and third embodiments of the present invention, AlInP or AlGa having a lower refractive index than the p-type AlGaInP cladding layer is formed on both sides of the stripe.
Since an InP confinement layer or insulating film is formed, it is possible to confine and guide light even in directions parallel to the active layer, and therefore refractive index waveguide is performed both in parallel and perpendicular directions to the active layer. Therefore, the astigmatism difference is also much smaller than that of the conventional laser. In addition, the AlInP or AlGaInP optical confinement layer, which has a lower refractive index than the p-type AlGaInP cladding layer provided on both sides of the stripe, or the insulating film does not absorb the light emitted by the active layer, so the loss of light is reduced and the oscillation threshold is reached. The value is also much smaller than that of the laser shown in the conventional example.

In the structure of the second embodiment of the present invention, the natural superlattice existing in the active layer on both sides of the stripe is disordered, the band gap becomes wider and the refractive index becomes smaller, so that It is possible to confine and guide light, and therefore, the refractive index is guided in both directions parallel and perpendicular to the active layer, so the astigmatism difference is also much smaller than in the laser shown in the conventional example. Furthermore, since the disordered active layers on both sides of the stripe do not absorb the light emitted by the active layer, the loss of light is reduced and the oscillation threshold value is much smaller than that of the conventional laser.

Furthermore, the aspect ratio of the light emission angle is smaller than that of the conventional example, and the angle becomes closer to a circle. In the manufacturing method of the first embodiment of the present invention, the AlInP optical confinement layer is made of n-type GaAs.
Selective etching can be easily performed using the block layer as a mask, and when growing the p-type AlGaAs upper cladding layer, the surface of the AlInP optical confinement layer containing Al, which is easily oxidized, is covered with the n-type GaAs block layer. Therefore, it is possible to grow crystals with good crystallinity.

[0034] In the manufacturing method of the second embodiment of the present invention, p
The heat applied when forming the upper mold cladding layer and the p-type contact layer diffuses impurities from the AlInP confinement layer, disordering the active layer below the AlInP confinement layer, which simplifies the process and allows for the formation of striped openings. Both sides of can be automatically disordered.

In the manufacturing method of the third embodiment of the present invention, the insulating film is formed from the surface of the p-type GaInP etch stop layer to the n-type GaInP etch stop layer.
Since it covers the side surfaces of the aAs block layer, no defects occur even if the p-type AlGaAs upper cladding layer does not grow on top of the insulating film.

[Brief explanation of the drawing]

FIG. 1 is a schematic structural cross-sectional view of a semiconductor laser according to a first embodiment of the present invention.

FIG. 2 is a first structural cross-sectional schematic diagram in the manufacturing process of the semiconductor laser according to the first embodiment of the present invention.

FIG. 3 is a second structural cross-sectional schematic diagram in the manufacturing process of the semiconductor laser according to the first embodiment of the present invention.

FIG. 4 is a third structural cross-sectional schematic diagram in the manufacturing process of the semiconductor laser according to the first embodiment of the present invention.

FIG. 5 is a first structural cross-sectional schematic diagram in the manufacturing process of a semiconductor laser according to a second embodiment of the present invention.

FIG. 6 is a second structural cross-sectional schematic diagram in the manufacturing process of a semiconductor laser according to a second embodiment of the present invention.

FIG. 7 is a third structural cross-sectional schematic diagram in the manufacturing process of the semiconductor laser according to the second embodiment of the present invention.

FIG. 8 is a schematic structural cross-sectional view of a semiconductor laser according to a second embodiment of the present invention.

FIG. 9 is a first structural cross-sectional schematic diagram in the manufacturing process of a semiconductor laser according to a third embodiment of the present invention.

FIG. 10 is a second structural cross-sectional schematic diagram in the manufacturing process of a semiconductor laser according to a third embodiment of the present invention.

FIG. 11 is a third structural cross-sectional schematic diagram in the manufacturing process of a semiconductor laser according to a third embodiment of the present invention.

FIG. 12 is a fourth structural cross-sectional schematic diagram in the manufacturing process of a semiconductor laser according to a third embodiment of the present invention.

FIG. 13 is a schematic structural cross-sectional view of a semiconductor laser according to a third embodiment of the present invention.

FIG. 14 is a schematic structural cross-sectional view of a conventional transverse mode control type AlGaInP semiconductor laser in a manufacturing process.

FIG. 15 is a schematic structural cross-sectional view of a conventional transverse mode control type AlGaInP semiconductor laser in a manufacturing process.

FIG. 16 is a schematic structural cross-sectional view of a conventional transverse mode control type AlGaInP semiconductor laser in a manufacturing process.

FIG. 17 is a schematic structural cross-sectional view of a conventional transverse mode control type AlGaInP semiconductor laser in each manufacturing process.

[Explanation of symbols]

101 n-type GaAs substrate 201 n-type GaAs substrate 301 n-type GaAs substrate 401 n-type GaAs substrate 102 n-type AlGaInP cladding layer 202 n
Type AlGaInP cladding layer 302 n-type AlGaI
nP cladding layer 402 n-type AlGaInP cladding layer 103 GaInP active layer 203 GaInP active layer 303 GaInP active layer 403 GaInP active layer 104 p-type AlGaInP cladding layer 204 p
Type AlGaInP cladding layer 304 p-type AlGaI
nP cladding layer 404 p-type AlGaInP cladding layer 105 p-type GaInP etch stop layer 205
p-type GaInP etch stop layer 305 p-type Ga
InP etch stop layer 405 p-type GaInP etch stop layer 106 p-type AlInP confinement layer 206 p-type AlInP confinement layer 107 n-type GaAs block layer 207 n-type GaAs block layer 306 n-type GaAs block layer 406 n-type GaAs block layer 108 SiO2 film 208 SiO2 film 308 SiO2 film 407 SiO2 film 109 p-type AlGaAs upper cladding layer 209
p-type AlGaInP upper cladding layer 309 p-type Al
GaAs upper cladding layer 110 p-type GaAs cap layer 210 p-type GaAs cap layer 310 p-type GaAs cap layer 408 p-type GaAs cap layer 111 Cr/Au electrode 211 Cr/Au electrode 311 Cr/Au electrode 409 Cr/Au electrode 112 Au /Ge/Ni electrode 212 Au/Ge/Ni electrode 312 Au/Ge/Ni electrode 410 Au/Ge/Ni electrode 51 Opening section 61 Opening section 71 Opening section 72 Opening section 220 Disordered layer

Claims (8)

[Claims] 1. One conductivity type AlGaInP cladding layer, an active layer, and the other conductivity type AlGaInP cladding layer are formed on one conductivity type GaAs substrate, and the other conductivity type AlGaInP has stripe-shaped openings on the cladding layer.
an AlInP or AlGaInP confinement layer having a refractive index lower than that of the nP cladding layer, and an upper cladding of the other conductivity type having a wider band gap and lower refractive index than the other conductivity type AlGaInP cladding layer on the confinement layer including the opening; A semiconductor laser characterized by having a layer. 2. One conductivity type AlGaInP cladding layer, an active layer, and the other conductivity type AlGaInP cladding layer are formed on one conductivity type GaAs substrate, and the cladding layer has stripe-shaped openings and contains Zn as an impurity. A
It has an lInP or AlGaInP confinement layer, and the AlInP or AlGaI
A semiconductor laser characterized in that the active layer below the nP confinement layer is disordered. 3. A striped insulating film having an AlGaInP cladding layer of one conductivity type, an active layer, and an AlGaInP cladding layer of the other conductivity type on one conductivity type GaAs substrate, and having striped openings on the cladding layer. is formed, and a one conductivity type blocking layer is formed on the outside of the insulating film, and at least on the striped openings and on the one conductivity type blocking layer, the band gap is lower than that of the other conductivity type AlGaInP cladding layer. 1. A semiconductor laser characterized by having an upper cladding layer of the other conductivity type and having a wide refractive index and a low refractive index. 4. The semiconductor according to claim 1 or claim 3, wherein the upper cladding layer of the other conductivity type, which has a wider band gap and lower refractive index than the AlGaInP cladding layer of the other conductivity type, is composed of AlGaAs. laser. 5. The semiconductor according to claim 1 or 3, wherein the upper cladding layer of the other conductivity type, which has a wider band gap and lower refractive index than the AlGaInP cladding layer of the other conductivity type, is composed of AlGaInP. laser. 6. One conductivity type AlGaInP cladding layer and active layer on one conductivity type GaAs substrate, and the other conductivity type AlGaInP cladding layer and active layer.
forming a GaInP cladding layer and an AlInP confinement layer; forming striped openings in the AlInP confinement layer;
1. A method for manufacturing a semiconductor laser, comprising a step of forming an upper cladding layer of the other conductivity type and a contact layer of the other conductivity type, each having a wider band gap and lower refractive index than the lGaInP cladding layer. 7. One conductivity type AlGaInP cladding layer and active layer on one conductivity type GaAs substrate, and the other conductivity type AlGaInP cladding layer and active layer.
A containing a GaInP cladding layer and Zn as an impurity
a step of forming an lInP confinement layer, a step of forming striped openings in the AlInP confinement layer, at least the striped openings and the AlInP
An upper cladding layer of the other conductivity type and a contact layer of the other conductivity type are formed on the confinement layer, and the impurities are diffused from the AlInP confinement layer by heat applied at this time to disorder the active layer under the AlInP confinement layer. 1. A method of manufacturing a semiconductor laser, comprising a step of converting the semiconductor laser. 8. One conductivity type AlGaInP cladding layer and active layer on one conductivity type GaAs substrate, and the other conductivity type AlGaInP cladding layer and active layer.
a step of forming a GaInP cladding layer and a block layer of one conductivity type; a step of forming striped openings in the block layer of the one conductivity type; a step of forming the AlGaInP cladding layer of the other conductivity type;
forming a striped insulating film having striped openings on the P cladding layer, forming a striped insulating film having striped openings on the P cladding layer; 1. A method of manufacturing a semiconductor laser, comprising a step of forming an upper cladding layer of the other conductivity type and a contact layer of the other conductivity type, each having a wide bandgap and a low refractive index.