JP2502835B2 - Semiconductor laser and manufacturing method thereof - Google Patents

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art Semiconductor lasers that emit visible light having a wavelength of 700 nm or less have been attracting attention as light sources used for optical disks, laser printers, bar code readers, and the like. Above all, GaAs is used as the substrate and Ga _0.5 is lattice-matched to this.
In _0.5 P (abbreviated as GaInP in the following description) or (Al _x Ga _{1 -x} ) _0.5 In _0.5 P (A in the following description
A double-heterojunction type semiconductor laser having a clad layer of AlGaInP or Al _y Ga _1-y As (abbreviated as AlGaAs in the following description) is an III-V group compound that is lattice-matched to GaAs. Since it can emit light with the shortest wavelength among semiconductors, it is a promising material for red semiconductor lasers.

14 to 17 show sectional structures of respective conventional internal stripe type AlGaInP based semiconductor lasers in a manufacturing process. First, as shown in FIG. 14, on the surface of an n-type GaAs substrate 401, n-type AlGaI is formed.
nP clad layer 402, GaInP active layer 403, p-type AlGaInP clad layer 404, p-type GaInP etch stop layer 405 and n-type GaAs block layer 40.
6 is sequentially grown by MO-VPE method (metal organic chemical vapor deposition method). Next, as shown in FIG. 15, n-type Ga is formed using the SiO ₂ film 407 having stripe-shaped openings as a mask.
The As block layer 406 is formed by, for example, H ₂ SO ₄ : H ₂ O ₂ : H ₂
Etching is performed with a mixed solution of O = 1: 1: 10. Next Si
After removing the O ₂ film 407, p-type G is formed by the MO-VPE method.
FIG. 16 shows the crystal growth of the aAs cap layer 408. Finally, a p-type ohmic contact electrode 409 made of Cr / Au is formed on the front surface, the back surface is polished and etched to thin the substrate, and then Au / Ge / Ni is formed.
When an n-type ohmic contact electrode 410 made of Al is formed, as shown in FIG. 17, a conventional internal stripe type Al is formed.
The GaInP semiconductor laser is completed.

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

[0005]

In such a conventional internal stripe type AlGaInP-based semiconductor laser, although the current is constricted, it is a gain waveguide type for light, so that it becomes an active layer. There is a problem that the wavefront of the guided light in the parallel direction is bent, resulting in a large astigmatic difference of about 40 μm. Therefore, when the conventional internal stripe type AlGaInP-based semiconductor laser is applied to optical equipment, the application range is limited because the laser light cannot be collimated into parallel light or focused at one point with one ordinary convex lens. It was dead.

Further, since the n-type GaAs block layer 406 and the p-type GaAs cap layer 408 absorb the light emitted from the active layer, the light guided through the active layer becomes a loss and the current confinement is improved. P-type AlGaI
When the thickness of the nP clad layer is made thin, the absorption of light becomes large and the oscillation threshold value increases by the amount of this loss, and it is difficult to lower the oscillation threshold value to 70 mA or less. .

[0007]

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

[0008]

The present invention having the above-described structure of the present invention has the following operational effects.

In the configurations (1) and (3), the AlInP or AlGaInP confinement layer having a smaller refractive index than the p-type AlGaInP cladding layer or the insulating film is formed on both sides of the stripe, so that it is parallel to the active layer. Light can be confined and guided, and therefore, the astigmatic difference is much smaller than that of the laser shown in the conventional example because the refractive index is guided both in the direction parallel to the active layer and in the direction perpendicular to the active layer. In addition, since the AlInP or AlGaInP confinement layer having a smaller refractive index than the p-type AlGaInP clad layer provided on both sides of the stripe or the insulating film does not absorb the light emitted from the active layer, the light loss is reduced and the oscillation threshold value is reduced. Is much smaller than the laser shown in the conventional example.

In the structure (2), the natural superlattices existing in the active layers on both sides of the stripe are disordered to widen the band gap and reduce the refractive index, so that light is confined in the direction parallel to the active layers. Since the light can be guided, and therefore the refractive index is guided both in the direction parallel to the active layer and in the direction perpendicular to the active layer, the astigmatic difference becomes much smaller than that of the laser shown in the conventional example. Further, since the disordered active layers on both sides of the stripe do not absorb the light emitted from the active layer, the loss of light is reduced and the oscillation threshold is much smaller than that of the laser shown in the conventional example.

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

In the manufacturing method of the structure (5), impurities are diffused from the AlInP confinement layer by heat applied when the p-type upper cladding layer and the p-type contact layer are formed on the stripe-shaped opening and the AlInP confinement layer. Al I
Since the active layer under the nP confinement layer is disordered, the process is simple and both sides of the aperture on the stripe can be automatically disordered.

In the manufacturing method of the structure (6), the insulating film is p-type G
Since it is covered from the surface of the aInP etch stop layer to the side surface of the n-type GaAs block layer, it does not become defective even if the p-type AlGaAs upper clad layer does not grow on the insulating film.

[0014]

EXAMPLES The present invention will be described below with reference to examples. 2 to 4 and FIG. 1A of the first embodiment of the present invention
The typical cross-section structural drawing in each manufacturing process of 1GaInP type | system | group semiconductor laser is shown. First, as shown in FIG. 2, for example, an n-type GaAs substrate 101 having a (100) plane as a main surface
On the surface of the n-type AlGaInP cladding layer 102 (for example, x = 0.6, carrier density 7 × 10 ¹⁷ cm ⁻³ , thickness 1
μm), the GaInP active layer 103 (for example, the thickness is 0.08).
μm), the p-type AlGaInP cladding layer 104 (for example, x = 0.6, carrier density 4 × 10 ¹⁷ cm ⁻³ , thickness 0.
1 μm), p-type GaInP etch stop layer 105 (for example, carrier density 1 × 10 ¹⁸ cm ⁻³ , thickness 0.01 μm).
m), p-type AlInP confinement layer 106 (for example, carrier density 4 × 10 ¹⁷ cm ⁻³ , thickness 0.3 μm), n-type Ga
As block layer 107 (for example, carrier density 1 × 10 ¹⁸
cm ⁻³ , thickness 0.5 μm) by n-type Ga by MO-VPE method
Crystals are sequentially grown while being lattice-matched with the As substrate 101. Next, for example, SiO ₂ is formed with stripes having a width of 3 μm.
Using the film 108 as a mask, the n-type GaAs block layer is etched with, for example, a mixed solution of H ₂ SO ₄ : H ₂ O ₂ : H ₂ O = 1: 1: 10, and the n-type GaAs block layer is used as a mask to p-type AlInP. The confinement layer 106 is, for example, 30 ° C.
Etching with hot concentrated sulfuric acid until the p-type GaInP etch stop layer 104 is reached, an opening 51 is formed as shown in FIG. In this embodiment, for example, when the stripes are formed in the <011> direction, the p-type AlInP confinement layer 106 and the n-type Ga on both sides of the stripe opening 51 are formed.
The As block layer is etched in a forward taper shape. Next, the SiO ₂ film 108 is removed, and p is formed by MO-VPE.
Type AlGaAs upper cladding layer 109 (for example, Al composition y = 0.7, carrier density 1 × 10 ¹⁸ cm ⁻³ , thickness 0.
5 μm) and the p-type GaAs cap layer 110 (for example, carrier density 5 × 10 ¹⁸ cm ⁻³ , thickness 3 μm) are crystal-grown on the entire surface, as shown in FIG. Finally C on the surface
p-type ohmic contact electrode 111 made of r / Au
Is formed, the back surface is polished and etched to thin the substrate, and then an n-type ohmic contact electrode 112 made of Au / Ge / Ni is formed. As shown in FIG. 1, the AlGaInP-based semiconductor of the first embodiment of the present invention is formed. The laser is completed.

The feature of the first embodiment of the present invention described above is that the p-type AlInP confinement layer 106 having a refractive index smaller than that of the p-type AlGaInP cladding layer 102 is formed on both sides of the stripe. Light can be confined and guided also in the direction parallel to 103, and therefore the refractive index is guided both in the direction parallel to the active layer 103 and in the direction perpendicular to the active layer 103, so that the astigmatic difference is larger than that of the laser shown in the conventional example. It will be much smaller. For example, in the case of the first embodiment of the present invention, the astigmatic difference was as small as 3 μm. Also, p-type A provided on both sides of the stripe
p having a smaller refractive index than the lGaInP clad layer 102
Since the type AlInP confinement layer 106 does not absorb the light emitted from the active layer 103, the loss of light is reduced and the oscillation threshold is much smaller than that of the laser shown in the conventional example.
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 was there can be reduced to 3.3 and approach a circle.

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 n.
The surface of the AlInP optical confinement layer 106 containing Al that can be easily selectively etched using the n-type GaAs block layer 107 as a mask and is easily oxidized during crystal growth of the p-type AlGaAs upper cladding layer 109 is n-type GaA.
Since it is covered with the s-block layer 107, it is possible to grow a good crystal with good crystallinity.

Of course, even if the conductivity type of the p-type AlInP confinement layer 106 in the first embodiment of the present invention is changed to the n-type, the above characteristics can be obtained in the same manner.
Further, it is needless to say that the above-mentioned characteristics can be obtained similarly even if a p-type or n-type AlGaInP confinement layer having a smaller refractive index than the p-type AlGaInP cladding layer 102 is used instead of the p-type AlInP confinement layer 106.

In the first embodiment of the present invention, the n-type GaAs on the p-type AlInP confinement layer 106 is also used.
Even if the conductivity type of the block layer 107 is changed to p-type, p-type AlI
In the heterojunction between the nP confinement layer 106 and the p-type GaAs block layer, the band discontinuity existing in the valence band serves as a barrier against holes, so that the flow of current is blocked and the effect of current confinement is obtained. Needless to say, can be obtained similarly.

FIGS. 5 to 8 show Al of the second embodiment of the present invention.
Schematic in each manufacturing process of a GaInP semiconductor laser
A cross-sectional structure diagram is shown. First of all, as shown in FIG.
Of the n-type GaAs substrate 201 whose main surface is the (100) plane
On the surface, an n-type AlGaInP clad layer 202 (for example,
x = 0.6, carrier density 7 × 10¹⁷cm^-3, Thickness 1μ
m), the GaInP active layer 203 (for example, the thickness is 0.08 μm).
m), p-type AlGaInP clad layer 204 (eg x
= 0.6, carrier density 4 × 10¹⁷cm^-3, Thickness 0.1
μm), p-type GaInP etch stop layer 205 (eg,
If carrier density 1 × 10¹⁸cm^-3, Thickness 0.01μ
m), p-type AlInP closed with Zn as an impurity
Confinement layer 206 (eg carrier density 1 × 10¹⁸c
m^-3, Thickness 0.3 μm), n-type GaAs block layer 20
7 (eg carrier density 1 × 10¹⁸cm^-3, Thickness 0.5
μm) on the n-type GaAs substrate 201 by MO-VPE method.
The crystals are sequentially grown while being aligned with each other. Next, for example, a width of 3 μm
With stripes of SiO₂Membrane 208 as a mask
The n-type GaAs block layer is, for example, H₂SO_Four: H
₂O₂: H ₂Etching with a mixed solution of O = 1: 1: 1: 10,
Furthermore, using the n-type GaAs block layer as a mask, p-type Al is used.
The InP confinement layer 206 is p-doped with, for example, hot concentrated sulfuric acid at 30 ° C.
Until the type GaInP etch stop layer 204 is reached.
Then, the opening 61 is formed as shown in FIG.
Be done. In this embodiment, for example, stripes are <011>
If formed in the opposite direction, p-type Al on both sides of the stripe opening 61 is formed.
InP confinement layer 206 and n-type GaAs block layer
Is etched in a forward tapered shape. Then SiO₂Membrane 2
08 is removed and p-type AlGaIn is formed by the MO-VPE method.
P upper clad layer 209 (for example, Al composition x = 0.7,
Carrier density 5 × 10¹⁷cm^-3, Thickness 0.5 μm) and
And p-type GaAs cap layer 210 (for example, carrier density
5 × 10¹⁸cm^-3, Thickness 3 μm)
And as shown in FIG. 7, a p-type upper cladding layer 209 and
The heat applied when forming the p-type contact layer 210 causes Al
Zn is diffused from the InP confinement layer 206 to cause AlIn
The active layer 203 under the P confinement layer 206 is disordered
As a result, the disordered layer 220 is formed. Finally on the surface Cr /
Shaped p-type ohmic contact electrode 211 made of Au
The substrate was thinned by polishing and etching the back surface.
Later n-type ohmic contact made of Au / Ge / Ni
When the gate electrode 212 is formed, as shown in FIG.
The AlGaInP semiconductor laser of the second embodiment is completed.
You.

The feature of the second embodiment of the present invention described above is that the disordered layer 220 formed by disordering the natural superlattices present in the active layers 203 on both sides of the stripe has a wide bandgap. At the same time, since the refractive index also decreases, light can be confined and guided also 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 direction vertical to the astigmatic difference. Is much smaller than the laser shown in the conventional example. For example, in the case of the second embodiment of the present invention, the astigmatic 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 band gap of the active layer 2.
It is wider than that of No. 03, and does not absorb the light emitted from the active layer 203, so that the loss of light is reduced and the oscillation threshold is much smaller than that of 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 0 does not absorb light, the stripe width can be narrowed. Therefore, the light emission angle θ ‖ in the direction parallel to the active layer
Is 8 ° in the conventional example, but can be increased up to 11 ° in the present invention when the stripe width is 2.5 μm or less. In the second embodiment of the present invention, the direction perpendicular to the active layer is The light emission angle θ ⊥ becomes 36 ° and the aspect ratio θ
The value of ⊥ / θ‖, which was 4.5 in the conventional example, can be reduced to 3.3 and approached a circle.

The feature of the manufacturing process of the second embodiment of the present invention described above is that the stripe-shaped openings 61 and Al are formed.
The p-type upper clad layer 20 is formed on the InP confinement layer 206.
9 and the heat applied when forming the p-type contact layer 210 diffuses impurities from the AlInP confinement layer 206 to disorder the active layer 203 under the AlInP confinement layer 206 to form the disordered layer 220, so that the process is simple. Moreover, it is possible to automatically form the disordered layer 220 on both sides of the opening 61 on the stripe.

In the second embodiment of the present invention, the n-type GaAs on the p-type AlInP confinement layer 206 is used.
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 existing in the valence band serves as a barrier against holes, so that the flow of current is blocked and the effect of current confinement is obtained. Needless to say, can be obtained similarly.

9 to 13 show the third embodiment A of the present invention.
The typical cross-section structural drawing in each manufacturing process of 1GaInP type | system | group semiconductor laser is shown. First, as shown in FIG. 9, for example, an n-type GaAs substrate 301 having a (100) plane as a main surface
On the surface of the n-type AlGaInP cladding layer 302 (eg, x = 0.6, carrier density 7 × 10 ¹⁷ cm ⁻³ , thickness 1
μm), the GaInP active layer 303 (for example, the thickness is 0.08).
μm), a p-type AlGaInP cladding layer 304 (eg, x = 0.6, carrier density 4 × 10 ¹⁷ cm ⁻³ , thickness 0.
1 μm), p-type GaInP etch stop layer 305 (eg carrier density 1 × 10 ¹⁸ cm ⁻³ , thickness 0.01 μm)
m), n-type GaAs block layer 306 (for example, carrier density 1 × 10 ¹⁸ cm ⁻³ , thickness 0.5 μm) is MO-VP.
Crystal growth is sequentially performed by lattice matching with the n-type GaAs substrate 301 by the E method. Next, the n-type GaAs block layer is, for example, H ₂ SO ₄ : H ₂ O ₂ : H ₂ O = 1: 1: 1 with the SiO ₂ film 307 having a 5 μm wide stripe formed as a mask.
P-type GaInP etch stop layer 304 with a mixed solution of 10
When the etching is performed until it reaches, the opening 71 is formed as shown in FIG. In this embodiment, for example, if the stripes are formed in the <011> direction, the stripe apertures 71 are formed.
The n-type GaAs block layers 306 on both sides of are etched in a forward taper shape. Next, the SiO ₂ film 307 is removed and a stripe-shaped insulating film having a width of 6 μm, for example, having a stripe-shaped opening having a width of 2 μm, for example, SiO ₂ is newly formed.
_{2 When the} film 308 is formed, as shown in FIG.
Is formed. Here, the opening 72 of the SiO ₂ film 308 is formed so as to be located on the surface of the p-type GaInP etch stop layer 304. Next, p-type A is formed by the MO-VPE method.
lGaAs upper clad layer 309 (for example, Al composition y =
0.7, carrier density 1 × 10 ¹⁸ cm ⁻³ , thickness 0.5 μ
m) and p-type GaAs cap layer 310 (for example, carrier density 5 × 10 ¹⁸ cm ⁻³ , thickness 3 μm) are crystal-grown on the entire surface, as shown in FIG. Depending on the crystal growth conditions, the p-type AlGaAs upper cladding layer 309 or the p-type GaAs cap layer 3 may be formed on the surface of the SiO ₂ film 308.
There is a case where 10 does not grow crystal, but even in that case, it is essentially irrelevant to the operation of the AlGaInP based semiconductor laser of the third embodiment of the present invention. Finally Cr / Au on the surface
When a p-type ohmic contact electrode 311 made of is formed, and the back surface is polished and etched to make the substrate thin, and then an n-type ohmic contact electrode 312 made of Au / Ge / Ni is formed, as shown in FIG. The AlGaInP based semiconductor laser of the third embodiment is completed.

The above-mentioned third embodiment of the present invention is characterized.
However, structurally, p-type AlGaI is formed on both sides of the stripe.
An insulating film (S having a refractive index smaller than that of the nP clad layer 304)
iO ₂Since the film 308) is formed, it is parallel to the active layer.
The point that light can be confined and guided in the direction
Therefore, both the direction parallel to the active layer and the direction perpendicular to the active layer
Since the refractive index is guided, the astigmatic difference is also shown in the conventional example.
Much smaller than that. Again stripes
Embedded on both sides of₂The thermal conductivity of the film 308 is G
Although lower than aAs, in the third embodiment of the present invention
Is SiO₂The film thickness of the film 308 can be reduced to about 0.1 μm.
Moreover, SiO₂The membrane 308 is embedded in the stra
Outside of the openings 71 on both sides of the Ip
Is the n-type GaAs block layer 306, the active layer
The heat generated in the vicinity is generated by the n-type GaAs block layer 306.
Is dissipated and SiO₂The heat dissipation is bad due to the film 308
It never happens.

Further, since the SiO ₂ film 308 has an extremely small light absorption coefficient, the light loss is reduced and the oscillation threshold is much smaller than that of the laser shown in the conventional example. For example, in the case of the third embodiment of the present invention, the oscillation threshold value was as small as 20 mA. Furthermore, the SiO ₂ 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 third embodiment, 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, but 2.4.
Can be reduced to a circle.

The feature of the manufacturing process of the third embodiment of the present invention described above is that the SiO ₂ 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. Therefore, even if the p-type AlGaAs upper clad layer 309 does not grow on the insulating film, the defect does not occur.

Further, the feature of the third embodiment of the present invention is that
SiO on both sides of the tripe ₂Outside the membrane 308
In the region, a GaAs layer 30 that absorbs the light emitted from the active layer
There is six. That is, in the plane parallel to the active layer
The lateral mode, which is the distribution of the guided modes of the
The more the light seeps to both sides of the stripe
And the light confinement factor inside the stripe is small.
Become. Therefore, in the semiconductor laser of the third embodiment of the present invention,
The higher the lateral mode becomes, the higher the GaAs
A greater amount of light is absorbed in layer 306. Therefore higher order
Lateral modes are more likely to be suppressed,
Since it becomes easier to oscillate, the optical output pair caused by the mode jump
Bending of current characteristics is unlikely to occur and stable operation is obtained.
Be done.

Although GaInP is used as the active layer in the above-described first to third embodiments of the present invention, it is needless to say that it may be AlGaInP. As for the conductivity type, the p-type and the n-type may be interchanged.

Further, in the above-mentioned first and third embodiments of the present invention, the p-type AlGaAs layer 1 is used as the upper cladding.
I explained the structure using 09 or 309,
It goes without saying that the same applies if a p-type AlGaInP layer is used instead. Further, although the structure using the p-type AlGaInP layer 209 as the upper clad has been described in the second embodiment of the present invention, the p-type A is used instead.
It goes without saying that the same applies when the 1GaAs layer is used.

[0030]

As described above, the present invention has the following effects.

In the structures of the first and third embodiments of the present invention, AlInP or AlGa whose refractive index is smaller than that of the p-type AlGaInP cladding layer on both sides of the stripe.
Since the InP confinement layer or the insulating film is formed, the light can be confined and guided also in the direction parallel to the active layer, so that the refractive index is guided in both the direction parallel to the active layer and the direction perpendicular thereto. Therefore, the astigmatic difference is much smaller than that of the laser shown in the conventional example. Further, since the AlInP or AlGaInP optical confinement layer having a smaller refractive index than the p-type AlGaInP clad layer provided on both sides of the stripe or the insulating film does not absorb the light emitted from the active layer, the loss of light is reduced and the oscillation threshold is generated. The value is 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 superlattices existing in the active layers on both sides of the stripe are disordered to widen the bandgap and reduce the refractive index, so that the direction parallel to the active layer is obtained. Also, the light can be confined and guided, and therefore the refractive index is guided both in the direction parallel to the active layer and in the direction perpendicular to the active layer, so that the astigmatic difference becomes much smaller than that of the laser shown in the conventional example. Further, since the disordered active layers on both sides of the stripe do not absorb the light emitted from the active layer, the loss of light is reduced and the oscillation threshold is much smaller than that of the laser shown in the conventional example.

Further, the light emission angle also has a smaller aspect ratio than that of the conventional example and is close 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.
The AlInP optical confinement layer containing Al, which can be easily selectively etched using the block layer as a mask and is easily oxidized during crystal growth of the p-type AlGaAs upper cladding layer, is covered with the n-type GaAs block layer. Therefore, a good crystal with good crystallinity can be grown.

In the manufacturing method of the second embodiment of the present invention, p is formed on the stripe-shaped openings and the AlInP confinement layer.
The process is simple because the impurities are diffused from the AlInP confinement layer and the active layer under the AlInP confinement layer is disordered by the heat applied when forming the p-type upper cladding layer and the p-type contact layer. Both sides of can be chaotic automatically.

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 G.
Since the p-type AlGaAs upper clad layer is covered over the side surface of the aAs block layer so as not to be defective, the p-type AlGaAs upper clad layer does not grow on the insulating film.

[Brief description of drawings]

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 view in the manufacturing process of the semiconductor laser according to the first embodiment of the present invention.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

[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 clad layer 202 n-type AlGaInP clad layer 302 n-type AlGaInP clad layer 402 n-type AlGaInP clad layer 103 GaInP active layer 203 GaInP Active layer 303 GaInP active layer 403 GaInP active layer 104 p-type AlGaInP clad layer 204 p-type AlGaInP clad layer 304 p-type AlGaInP clad layer 404 p-type AlGaInP clad layer 105 p-type GaInP etch stop layer 205 p-type GaInP etch stop layer 305 Type GaInP etch stop layer 405 p type GaInP etch stop layer 106 p type AlInP confinement layer 206 p type AlI nP 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 SiO ₂ film 208 SiO ₂ film 308 SiO ₂ film 407 SiO ₂ film 109 p-type AlGaAs upper clad layer 209 p-type AlGaInP upper clad layer 309 p-type AlGaAs upper clad 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 portion 61 Opening portion 71 Opening portion 72 Opening Part 220 disordered layer

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Claims (8)

(57) [Claims] 1. A one conductivity type AlGaInP clad layer, an active layer, and the other conductivity type A on a one conductivity type GaAs substrate.
a GaInP clad layer, and stripe-shaped openings on the clad layer, and the other conductivity type AlGaIn
An AlInP or AlGaInP confinement layer having a smaller refractive index than the P clad layer, and the other conductivity type upper clad having a wider band gap and a lower refractive index than the other conductivity type AlGaInP clad layer on the confinement layer including the opening. A semiconductor laser having a layer. 2. A first conductivity type AlGaInP cladding layer, an active layer and a second conductivity type A on a first conductivity type GaAs substrate.
Al having a 1GaInP clad layer, stripe-shaped openings on the clad layer, and Zn as an impurity
An InP or AlGaInP confinement layer is provided, and the AlInP or AlGaIn is diffused by diffusion of impurities from the AlInP or AlGaInP confinement layer.
A semiconductor laser, wherein the active layer below the P confinement layer is disordered. 3. One conductivity type AlGaInP clad layer, active layer and other conductivity type A on one conductivity type GaAs substrate.
a stripe-shaped insulating film having a 1GaInP clad layer and having a stripe-shaped opening on the clad layer, and a first conductivity type block layer is formed outside the insulating film, and at least the stripe-shaped insulating film is formed. Of the other conductivity type A on the opening and the one conductivity type block layer.
A semiconductor laser having a second conductivity type upper clad layer having a wider bandgap and a lower refractive index than the lGaInP clad layer. 4. The semiconductor according to claim 1, wherein the other conductivity type upper cladding layer having a wider band gap and a lower refractive index than the other conductivity type AlGaInP cladding layer is made of AlGaAs. laser. 5. The semiconductor according to claim 1, wherein the other conductivity type upper clad layer having a wider band gap and a lower refractive index than the other conductivity type AlGaInP clad layer is composed of AlGaInP. laser. 6. One conductivity type AlGaInP clad layer, active layer, and other conductivity type AlG on one conductivity type GaAs substrate.
a step of forming an aInP clad layer and an AlInP confinement layer, a step of forming a stripe-shaped opening in the AlInP confinement layer, the other conductivity type Al on the AlInP confinement layer and the stripe-shaped opening
A method of manufacturing a semiconductor laser, comprising a step of forming a second conductivity type upper clad layer and a second conductivity type contact layer having a wider bandgap and a lower refractive index than the GaInP clad layer. 7. One conductivity type AlGaInP clad layer, active layer, and other conductivity type AlG on one conductivity type GaAs substrate.
aInP clad layer and Al containing Zn as an impurity
Forming an InP confinement layer, forming a stripe-shaped opening in the AlInP confinement layer, at least the stripe-shaped opening and the AlInP confinement layer, the other conductivity type upper cladding layer and the other conductivity type When the contact layer is formed and the heat applied at that time causes the above A
By diffusing the impurities from the lInP confinement layer,
A method of manufacturing a semiconductor laser, comprising a step of disordering the active layer below an lInP confinement layer. 8. One conductivity type AlGaInP clad layer, active layer, and other conductivity type AlG on one conductivity type GaAs substrate.
forming an aInP clad layer and one conductivity type block layer, forming a stripe-shaped opening in the one conductivity type block layer, the other conductivity type AlGaInP
A step of forming a stripe-shaped insulating film having stripe-shaped openings on the clad layer, at least on the stripe-shaped openings and the one conductivity type block layer, and more than the other conductivity type AlGaInP clad layer; 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 having a wide band gap and a low refractive index.