JPH0629614A - Semiconductor laser element and manufacturing method thereof - Google Patents

Abstract

PURPOSE:To provide the title semiconductor beam emitting element in high reliability capable of stably oscillating basic lateral mode in high differential efficiency even in low threshold value current and high output. CONSTITUTION:The third AlwGa1-wAs clad layer 9 is formed on a current strangulating stripe trench 112 so that the refractive index of the part 115 above the bottom 114 of the stripe trench 112 may be larger than that of the parts 116, 116 above both sides 113, 113 of the stripe trench 112 thereby enabling a refractive index waveguide based on the effective difference in the refractive index to be formed. Accordingly, the basic lateral mode of the beams emitted by an active layer 3 can be enclosed with this refractive index waveguide.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor laser device, and more particularly to a semiconductor laser device which has a low threshold current, can oscillate with high efficiency, and can operate in a fundamental transverse mode even in the case of high output, and a method for manufacturing the same. It is about.

[0002]

2. Description of the Related Art Semiconductor laser devices are applied in many fields and are required to have better optical characteristics. In order to obtain excellent optical characteristics, many semiconductor laser devices adopting a refractive index waveguide structure have been proposed, and for example, a refractive index waveguide type stripe laser device as shown in FIG. 9 can be mentioned. This semiconductor laser device is an n-type G
A p-type GaAs semiconductor substrate 91 on which an aAs current blocking layer 92 is laminated has a stripe-shaped groove 93 having a V-shaped cross section, and a p-type AlGaAs first cladding layer 94, an AlGaAs active layer 95, n. A type AlGaAs second cladding layer 96 and an n-type GaAs contact layer 97 are laminated.

In this semiconductor laser device, the current is confined in the groove 93 formed in the current blocking layer 92. The current blocking layer 92 has a smaller bandgap than the active layer 95 and has a light absorbing function. Therefore, the effective refractive index decreases on both side surfaces of the groove 93, and the effective refractive index waveguide is formed in this portion. In the semiconductor laser device having such a structure, the current blocking layer 92
Due to the light absorption effect of, the higher-order transverse mode gain is suppressed, and stable fundamental transverse mode operation is obtained.

[0004]

However, in the semiconductor laser device shown in FIG. 9, the fundamental transverse mode is also lost to some extent by the light absorption effect of the current blocking layer 92, so that the differential efficiency is lowered and the oscillation threshold current is reduced. It has the drawback of increasing. In particular, when this semiconductor laser device is operated at a high output, there are drawbacks that the operating current increases and the reliability of the device decreases.

The present invention is intended to solve the above-mentioned drawbacks, and the first object thereof is that the threshold current is low and the fundamental transverse mode oscillation can be stably performed with high differential efficiency even at high output, It is to provide a semiconductor laser device having excellent reliability.

A second object of the present invention is to provide a method capable of suitably manufacturing the above semiconductor laser device.

[0007]

In the semiconductor light emitting device of the present invention, the active layer (y is 0 or more and 1 or less) made of Al _y Ga _1-y As is made of Al _x Ga _1-x As on both sides in the vertical direction. It is separated from the light emitting layered portion sandwiched between the first cladding layer (x is 0 or more and 1 or less) and the second cladding layer (z is 0 or more and 1 or less) made of Al _z Ga _{1 -z} As. A stripe groove for current constriction is formed between two current blocking layers, and a third clad layer made of Al _w Ga _1-w As (where w is greater than 0 is formed on the current blocking layer including the stripe groove). Current confinement mechanism section having a value less than 1) on a GaAs substrate, and a portion of the third cladding layer above the bottom of the stripe groove has a refractive index above both side surfaces of the stripe groove. The refractive index is higher than the refractive index of a certain portion, thereby achieving the first object.

Further, in the third cladding layer, it is preferable that the conductivity type of a portion above the bottom of the stripe groove is different from the conductivity type of a portion above both side surfaces of the stripe groove.

The method of manufacturing a semiconductor laser device according to the present invention comprises:
Active layer made of Al _y Ga _1-y As (y is 0 or more and 1 or less)
A first clad layer made of Al _x Ga _1-x As (x is 0 or more and 1 or less) and a second clad layer made of Al _z Ga _1-z As (z is 0 or more and 1 or less) on both upper and lower sides of A stripe groove for current confinement is formed between the sandwiched light emitting laminated portion and two separated current blocking layers, and Al _w Ga _1-w is formed on the current blocking layer including the stripe groove. A method of manufacturing a semiconductor laser device, comprising: a current confinement mechanism portion including a third cladding layer (w is greater than 0 and less than 1) made of As on a GaAs substrate, wherein the laminated portion for light emission is provided. Forming step, and the plane orientation of the bottom of the stripe groove is set to (100) and the plane orientation of both side surfaces thereof is set to (n11) (n is 1 or more and 8 or less), and on the current blocking layer including the stripe groove. Third
By laminating the cladding layers, the refractive index of the portion of the third cladding layer above the bottom of the stripe groove is higher than the refractive index of the portions above both side surfaces of the stripe groove. And the step of forming, whereby the second object is achieved.

In this method of manufacturing a semiconductor laser device, the third cladding layer may be formed by doping an amphoteric impurity.

Another semiconductor laser device of the present invention is
Active layer made of Al _y Ga _1-y As (y is 0 or more and 1 or less)
The first clad layer (x is 0 or more and 1 or less) made of Al _x Ga _1-x As and the second clad layer (z made of Al _z Ga _1-z As having a ridge portion for current confinement) on both sides in the vertical direction of Is 0
A light emitting layered portion sandwiched between (1 and below) and the second cladding layer including at least both side surfaces of the ridge portion, and a third cladding layer made of Al _w Ga _1-w As (where w is Greater than 0 and less than 1) on the GaAs substrate, and the refractive index of the ridge is larger than the refractive index of the portions of the third cladding layer above both sides of the ridge. According to the above, the first object is achieved.

Further, the conductivity type of the ridge and the third type
It is preferable that the portions above the both side surfaces of the ridge in the clad layer have different conductivity types.

According to another method of manufacturing a semiconductor laser device of the present invention, Al _x Ga _1-x As is formed on both upper and lower sides of an active layer (y is 0 or more and 1 or less) made of Al _y Ga _1-y As. For light emission sandwiched between a first cladding layer (x is 0 or more and 1 or less) and a second cladding layer (z is 0 or more and 1 or less) made of Al _z Ga _1-z As having a ridge portion for current confinement And a second portion including at least both side surfaces of the ridge portion.
A method of manufacturing a semiconductor laser device comprising a GaAs substrate and a third clad layer (w is greater than 0 and less than 1) made of Al _w Ga _1-w As on the clad layer. The plane orientations of both side surfaces are (n11) (n is 1 or more and 8 or less), and the plane orientations of the second clad layer portions on both sides of the ridge portion are set to (100). The third clad layer is formed so that the refractive index of the ridge portion is higher than the refractive index of the portions of the third clad layer above both side surfaces of the ridge portion, thereby achieving the second object. It

In this method of manufacturing a semiconductor laser device, the third cladding layer may be formed by doping an amphoteric impurity.

[0015]

In the semiconductor laser device of the present invention, the refractive index of the portion above the bottom of the stripe groove in the third cladding layer formed on the stripe groove for current constriction is
Since it is formed to have a larger refractive index than the portion above both side surfaces of the stripe groove, a refractive index waveguide based on the effective refractive index difference is formed in this portion.

Further, in another semiconductor laser device, the refractive index of the ridge portion for current confinement is formed to be higher than the refractive index of the portions of the third cladding layer above both side surfaces of the ridge portion. Therefore, the refractive index waveguide based on the effective refractive index difference is formed in this portion.

In any of these semiconductor laser devices, the fundamental transverse mode of light generated in the active layer is confined by the refractive index waveguide formed in each.

In the manufacturing method of the present invention, the layer provided with the groove or the ridge portion for the current constriction has the (n11) plane (n is 1).
8 or more) and (100) plane, and Al _w Ga _1-w As
A third cladding layer consisting of is laminated on this layer. G
The migration of a atoms is (n1
1) The surface is larger, but the migration size of Al atoms is not so different as that of Ga atoms even if the plane orientation is different. Therefore, the Al mixed crystal ratio of the portion formed on the (n11) plane in the third cladding layer is (1
Since it is larger than the Al mixed crystal ratio of the portion formed on the (00) plane, the refractive index of the portion formed on the (100) plane is formed on the (n11) plane of the third cladding layer. It will be larger than the part. By thus differentiating the plane orientations, the refractive index waveguide is manufactured at the same time when the third cladding layer is laminated.

[0019]

Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1) FIG. 1 is a diagram showing a manufacturing process of a semiconductor laser device according to Embodiment 1 of the present invention. First, Fig. 1
As shown in (a), (100) of the n-type GaAs substrate 1
Al _x Ga _1-x As first clad layer 2, Al _y Ga _1-y As active layer 3, p-type Al _z Ga on the surface by a normal method.
A laminated portion for light emission composed of the _1-z As second cladding layer 4 is formed, and the p-type GaAs first protective layer 5 is further formed thereon.
n-type Al _s Ga _1-s As etching stop layer 6 (s is 0
The maximum is 1 or less), and the n-type GaAs current blocking layer 7 is sequentially formed. The above is produced in the first growth step.

Next, on the epitaxial wafer obtained above, as shown in FIG. 1 (b), a stripe-shaped photoresist pattern 11 is formed by a photolithography technique.
1 is formed. After that, this photoresist pattern 11
Using 1 as an etching mask, the current blocking layer 7 is etched using a GaAs selective etching solution until the surface of the etching stop 6 is reached. As a result, the current blocking layer 77 is separated, and the stripe groove 112 is formed between them. Both side surfaces 113, 113 of the stripe groove 112 are symmetrical (n11) planes. The bottom 114 of the stripe groove 112 becomes the (100) plane.

Subsequently, as shown in FIG. 1C, AlGa
The etching stop layer 6 is removed using an As selective etching solution, and then the photoresist pattern 111 is removed.

After removing the etching stop layer 6, in the second growth step by the MBE (molecular beam epitaxy) method, p-type Al _w Ga _1-w As is formed on the current blocking layer 7 including the stripe groove 112. Third cladding layer 9 (w is 0
Greater than and less than 1). Stripe groove 1
The current blocking layer 7 including 12 and the third cladding layer 9 form a current confinement mechanism portion.

The third cladding layer 9 is formed on the side surfaces 116 and 116 formed on the side surfaces 113 and 113 of the stripe groove which is the (n11) plane and on the bottom 114 of the stripe groove which is the (100) plane. Further, the Al mixed crystal ratio of the side surface portion 116 is larger than the Al mixed crystal ratio of the central portion 115. Therefore, the refractive index of the central portion 115 is higher than that of the side surface portion 116. this is,
This is because the degree of migration of GaAs atoms is different between the (100) plane and the (n11) plane, and the GaAs layer thickness is different between the (100) plane and the (n11) plane.

This phenomenon is, for example, Appl.Phys.Lett.,56
(8), 776 (1990). As shown in Figure 2
And the horizontal plane 21 whose plane orientation is the (100) plane and the plane orientation
On the side surface 22 in which is the (411) plane, a layer is formed thereon.
There is a difference in the thickness of the GaAs layer formed. Like this
Ga migration due to the difference in each plane orientation
The degree of is different, and the (n11) plane is the (100) plane
Since the migration of Ga atoms is larger than that of (1
The (n11) plane is more laminated than the (00) plane.
The GaAs layer is less likely to grow when it is removed. Al
When stacking As layers, the GaAs layer has a different plane orientation.
There is no difference in layer thickness due to heat.

Flat (100) and (411) planes
When GaAs and AlAs are stacked on the (100) plane, GaA is stacked on the (100) plane as shown in Table 1 below.
s layer thickness is 70 Å, AlAs layer thickness is 100
Å, and when stacked on the (411) plane, the GaAs layer thickness is 25 Å, AlAs
The layer thickness is 80 Å. That is, (10
Compared to the (0) plane, the (411) plane has a GaAs layer thickness of 36
%, But the thickness of the AlAs layer is only about 80%.

Even in the uneven shape as shown in FIG. 2, such a tendency is observed in the GaAs layer thickness and the AlAs layer thickness, and the (411) plane and the (411) plane as shown in FIG.
The vertex A formed by the plane and the (411) plane and the (41
The bottom portion B, which is sandwiched between the (1) plane and the (100) plane, similarly causes a difference in layer thickness. Table 1 shows each layer thickness.

[0028]

[Table 1]

As described above, when AlGaAs is grown on the inner surface of the groove, the Al mixed crystal ratio of the layer formed on the side surface 22 becomes larger than that of the layer formed on the bottom 21. Such an effect due to the difference in plane orientation can be obtained in the range where n is 1 or more and 8 or less.

Table 2 below shows the side surface 1 of the groove in this embodiment.
13 is the (111) plane, the (311) plane, the (411) plane,
Side surface 113 when formed to be the (811) plane
And the Al mixed crystal ratio in the bottom 114 are shown.

[0031]

[Table 2]

When the second cladding layer 4 is grown by the MBE method, it is preferable to make the temperature of the substrate relatively high because the migration of Ga tends to increase. For example, the temperature is about 720 ° C. Further, the amount of As flux is reduced. For example, V / III = 5.

A p-type GaAs contact layer 10 is formed on the third cladding layer 9, and an n-type electrode 11 is formed on the substrate 1 side.
7. A p-type electrode 118 is formed on the contact layer 10 side.

In the first embodiment, the width w _{1 of the} groove 112 is 4 μm.
Then, the side surfaces 113 and 113 of the groove 112 are set to the (311) surface. The composition and thickness of each semiconductor layer laminated on the substrate 1 in this example are formed as follows, for example.

First cladding layer 2: n-type Al _x Ga _1-x A
s, x = 0.50, a thickness of 1 [mu] m, an active layer 3: Al _y Ga
_1-y As, y = 0.14, thickness 500 angstrom, second cladding layer 4: p-type Al _z Ga _1-z As, z = 0.5
0, thickness 0.3 μm, first protective layer 5: p-type GaAs, thickness 50 Å, etching stop layer 6: p
Type Al _s Ga _1-s As, s = 0.50, thickness 100 angstrom, current blocking layer 7: n-type GaAs, thickness 0.5
μm, third cladding layer 9: p-type Al _w Ga _1-w As, w =
0.50, thickness 1.5 μm, contact layer 10: p-type GaA
s, thickness 1 μm.

The Al mixed crystal ratio of the central portion 115 of the third cladding layer 9 is 0.50, and the Al mixed crystal ratio of the side surface portion 116 is 0.60.
Is. The side surface portion 116 is more than the Al mixed crystal ratio of the central portion 115
Since the Al mixed crystal ratio is large, the refractive index of the side surface portion 116 becomes smaller than the refractive index of the central portion 115, and a waveguide structure due to the difference in effective refractive index is formed in this portion. As a result, the light generated in the active layer 3 is confined, resulting in a semiconductor light emitting device having a low threshold current and high efficiency. Furthermore, Example 1
In the above, since the current blocking layer 7 is made of GaAs, a stable fundamental transverse mode oscillation can be obtained even at high output due to its light absorption effect. Further, the above-mentioned waveguide structure absorbs less light as compared with the conventional semiconductor light emitting device, so that astigmatism can be significantly improved.

Since the protective layer 5 is made of GaAs, its thickness is preferably 100 angstroms or less so that the light absorption effect does not hinder the above-mentioned waveguide structure. In Example 1, the thickness of the protective layer 5 is about 50 angstroms, which is sufficiently thin, and has almost no light absorption effect, which does not hinder the above-mentioned waveguide structure.

In the semiconductor laser device of Example 1, the threshold current, which was about 40 mA in the past, can be reduced by about 20 mA. Further, when operated at 50 mC and 70 mW, it was possible to operate for 50,000 hours or more, and high reliability was obtained.

By using the above manufacturing method,
The semiconductor laser device can be manufactured by two growth steps.

(Embodiment 2) The semiconductor laser device shown in FIG. 3 has the n-type Al _x Ga _{1 -x} on the n-type GaAs substrate 31.
As first cladding layer 32, Al _y Ga _1-y As active layer 3
3, p-type Al _z Ga _{1- z} As second cladding layer 34, p-type G
aAs first protective layer 35, n-type Al _s Ga _1-s As etching stop layer 36, n-type Al _u Ga _1-u As current blocking layer 3
7 (u is greater than 0 and 1 or less) is laminated.

In the second embodiment, the current blocking layer 37 is A
It is formed of 1 GaAs, and n is formed on the current blocking layer 37.
A type GaAs protective layer 38 is formed. In the present embodiment, since the current blocking layer 37 is made of AlGaAs, the Al _w Ga _1-w As third cladding layer 39 described later is formed as M.
This protective layer 38 is necessary when growing by the BE method.

A stripe groove 312 is formed in the current blocking layer 37 as in the first embodiment, and the stripe groove 31 is formed.
The second side surfaces 313 and 313 are (n11) planes, and the bottom 314 is a (100) plane. A third clad layer 39 and a contact layer 310 are formed on the n-type GaAs protective layer 38 by the MBE method as in the first embodiment. The electrodes 317 and 318 are similar to those in the first embodiment.

In this embodiment, the structure other than the current blocking layer 36 and the second protective layer 38 is the same as that of the first embodiment, and the central portion 315 of the third cladding layer 39 on the stripe groove 312 is formed.
Has a larger refractive index than the side surface portions 316 and 316.

The current blocking layer 37 is formed of n-type Al _u Ga _1-u As, has a mixed crystal ratio u of 0.20 and a thickness of 1 μm.
The protective layer 38 is made of p-type GaAs and has a thickness of 0.0.
It was set to 05 μm.

In Example 2, the current blocking layer 37 is A
Since it is formed of 1GaAs, light absorption in the current blocking layer is smaller than that in the first embodiment. This made it possible to obtain a lower threshold current and a higher differential efficiency.

The semiconductor laser device of this embodiment is 200 m long.
Even when operated in w, the fundamental transverse mode oscillation was stable.

In the semiconductor laser device of this embodiment, when the current blocking layer 37 is made of the same semiconductor as the third cladding layer 39, for example, the respective Al mixed crystal ratios u and w.
The same effect as above was obtained when and were 0.5.

(Embodiment 3) In the semiconductor laser device shown in FIG. 4, the conductivity type of the GaAs substrate 41 and the semiconductor layers laminated on the substrate 41 are opposite to those of the embodiment 2. There is. That is, this semiconductor laser device, on the p-type substrate 41, p-type Al _x Ga _1-x As first cladding layer _{42, Al y Ga 1-y} As active layer 43, n-type Al _z
A Ga _1-z As second cladding layer 44, an n-type GaAs first protective layer 45, a p-type Al _s Ga _1-s As etching stop layer 46, and a current blocking layer 47 are laminated. Also in this embodiment, the current blocking layer 47 is made of AlGaAs, and the n-type GaAs protective layer 4 is formed on the current blocking layer 47.
8 is formed. Stripe grooves 412 are formed in the current blocking layer 47 as in the first embodiment, and the side surfaces 413 and 413 of the stripe grooves 412 are (n11) planes and the bottoms 414 are (100) planes. A third clad layer 49 and a contact layer 410 are formed on the n-type GaAs protective layer 48.
Are formed.

Also in this semiconductor laser device, the refractive index of the central portion 415 of the third cladding layer 49 in the stripe groove 412 is larger than the refractive index of the side surface portions 416, 416.

The third cladding layer 49 is doped with amphoteric impurities such as Si. As a result, in the third cladding layer 49, hatched lines in the figure (n1
1) side surfaces 413, 4 of the stripe groove 412
The conductivity type of the side surface portions 416, 416 of the groove laminated on 13 is p-type, and the central portion 41 formed on the (100) plane.
5 and the outer parts 420, 4 of the side parts 416, 416
The conductivity type of 20 is n-type. The amphoteric impurity acts as an acceptor or a donor due to the difference in the plane orientation of the surface on which the third cladding layer 49 is laminated.
6, 416 and the central portion 415 have opposite conductivity types. In order to make effective use of such properties by using Si as the amphoteric impurity, the surface orientation (n1
N in 1) is preferably 1 or more and 3 or less.
In Example 3, the side surface 413 of the groove 412 is the (311) surface.

In this semiconductor laser device, since the width is narrowed by the width w ₂ of the central portion 415 of the stripe groove narrower than the width w ₁ narrowed by the current blocking layer 47, the narrowing width is further narrowed and the threshold current is further increased. Can be lowered.

The configuration in which the conductivity type is reversed and the current is further constricted in the central portion of the third cladding layer as described above is also applied to the semiconductor laser device of Example 1 in which the current blocking layer is made of GaAs. It is possible.

Example 4 In the semiconductor laser device shown in FIG. 5, an n-type Al _x Ga _1-x As first cladding layer 52, an Al _y Ga _1-y As active layer 53, p is formed on a substrate 51. Type Al _z
Ga _1-z As second cladding layer 54, p-type GaAs first protective layer 55, n-type Al _s Ga _1-s As etching stop layer 56, current blocking layer 57 made of n-type GaAs or n-type AlGaAs, third Cladding layer 59, contact layer 51
0, and the stripe groove 5 formed in the current blocking layer 57
The structure is almost the same as that of the first embodiment except that the cross-sectional shape of 12 is different. Side surfaces of the stripe groove 512 are surfaces 513a and 513b having different plane orientations (n ₁ 11) and (n ₂ 11). In this embodiment,
The lower side surfaces 513b and 513b are (311) planes, and the upper side surfaces 513a and 513a are (111) planes. Bottom 51
4 is the (100) plane.

Thus, the side surface 5 of the stripe groove 512 is
13, 513 are a plurality of planes 513 each having a different plane orientation.
a and 513b, the third cladding layer 5
Side portions 516a and 516 inside the stripe groove 512 of FIG.
The Al mixed crystal ratio of b changes, respectively.

(Embodiment 5) The present invention can be applied to a semiconductor laser device having a current confinement mechanism formed on the substrate side. An example thereof is shown in FIG.

In this semiconductor laser device, an n-type GaAs current blocking layer 62 is formed on the (100) plane of a p-type GaAs substrate 61.
Are stacked to form a stripe groove 6 in the current blocking layer 62.
12 is formed by etching. The side surfaces 613 and 613 of the stripe groove 612 are (n11) planes, and the bottom 614 is (100) plane. On top of that, Al _w
The Ga _{1 -w} As third cladding layer 69 is grown by the MBE method to form a current confinement mechanism portion.

In addition to the above structure, the p-type GaAs first protective layer 68 and the p-type Al are formed by the LPE (liquid phase epitaxy) method.
_x Ga _1-x As first cladding layer _{63, Al y Ga 1-y} As active layer 64, n-type Al _z Ga _1-z As second cladding layer 65,
A GaAs contact layer 66 is formed. further,
N-type electrode 617 on the substrate 61 side and p on the contact layer 66 side
A mold electrode 618 is formed.

As the material forming each semiconductor layer formed on the substrate 61 of the fifth embodiment, the same materials as those corresponding to the first embodiment can be used.

Also in the present embodiment, the Al mixed crystal ratio in the third cladding layer 69 is such that the side surface portions 616, 616 have the central portion 6 more.
It becomes larger than 15, and a waveguide structure is formed in this portion.

(Embodiment 6) The laser device shown in FIG. 7 has an n-type Al _x Ga _{1 -x} A on an n-type GaAs substrate 71.
A p-type A in which the first cladding layer 72, the Al _y Ga _1-y As active layer 73, and the stripe-shaped ridge portion 720 are formed.
1 _z Ga _{1 -z} As The light emitting layered portion including the second cladding layer 74, the GaAs protective layer 75, GaAs or Al.
A current blocking layer 77 made of GaAs is laminated. In this embodiment, current confinement is performed in the stripe-shaped ridge portion 720 formed in the second cladding layer 74. The ridge portion 7 is formed on the second cladding layer 74.
The Al _w Ga _1-w As third cladding layer 79 and the contact layer 710 are formed except for the upper portion of the layer 10. An n-type electrode 717 is formed on the substrate 71 side, and a p-type electrode 718 is formed on the contact layer 710 side. The refractive index of the ridge portion 720 is equal to that of the ridge side surface 71 of the third cladding layer 79.
3, 713, which is larger than the side parts 716, 716 on the
A waveguide structure is formed in this portion.

This semiconductor laser device can be manufactured as follows. First, (100) of the substrate 71
The protective layer 7 is formed on the surface in the first growth step by a normal method.
5 are stacked, and a dielectric film (not shown) made of, for example, Al ₂ O ₃ or the like is formed in stripes on the protective layer 75. Using this stripe as a mask, the second cladding layer 7
4 is etched so that the side surfaces 713 and 713 have a plane orientation of (n11) to form a ridge portion 720. Second
The clad layer 74 has p-type Ga as shown by the broken line in the figure.
When the etching stop layer 76 made of As is provided, it is possible to prevent excessive etching when the ridge portion 720 is formed by etching.

After forming the ridge portion 720, the third cladding layer 7 is formed.
9 and the current blocking layer 77 are formed in the second growth step by the MBE method. The plane directions of the ridge side surfaces 713 and 713 are (n11), and the plane directions of the second cladding layer portions 714 and 714 that sandwich the ridge section are (100).
Therefore, the ridge side surface 713 of the third cladding layer 79,
The mixed crystal ratio of the side surface portions 716 and 716 on the 713 is determined by the ratios of the portions 715 and 715 laminated on the portions 714 and 714.
The Al mixed crystal ratio becomes larger than that of
It becomes smaller than 15. Therefore, the second cladding layer 74
Even if the third clad layer 79 and the third clad layer 79 are made of the same material, that is, a material having substantially the same mixed crystal ratios z and w, the refractive index of the ridge portion 720 is the same as that of the side surface portions 716 and 7.
The refractive index may be larger than 16.

Further, in this embodiment, as in the third embodiment, the conductivity type of the side surface portion 716 and the conductivity type of the portion 715 are changed by doping the third cladding layer 79 with an amphoteric impurity such as Si. Can be configured differently. As a result, the current constriction width can be further reduced as in the third embodiment.

(Embodiment 7) The semiconductor laser device shown in FIG. 8 has an Al _x Ga layered on a GaAs substrate 81.
_1-x As first cladding layer 82, Al _y Ga _1-y As active layer 83, p-type Al _z Ga _1-z A with ridge 820 formed
s second cladding layer 83 and GaAs protective layer 85, and has a structure similar to that of the semiconductor laser device of Example 6, but in this Example, Al _w Ga _{1 -w} As third cladding layer 89 is used. It is formed so as to cover the entire ridge portion 820 and has no current blocking layer. The refractive index of 820 in the ridge is
It is larger than the side surface portions 816 and 816 on the ridge side surfaces 813 and 813 of the third cladding layer 89, and a waveguide structure is formed in this portion.

This semiconductor laser device can be manufactured using the growth method and etching method similar to those of the seventh embodiment. Further, in this semiconductor laser device, it is preferable that the second cladding layer 84 is provided with the GaAs etching stop layer 85 as shown by the imaginary line in the figure for the same reason as in the sixth embodiment.

Also in this embodiment, the side surface 813,
The plane orientation of 813 is (n11), and the plane orientation of the second cladding layer portions 814 and 814 sandwiching the ridge portion is (100).
Is. Therefore, the side surface 81 of the third cladding layer 89 is
The Al mixed crystal ratios of the side surface portions 816 and 816 on the surface of the ridge portion 820 are the same as those of the upper portion 821 of the ridge portion 820 and the portions 815 and 815 laminated on the second cladding layer portions 814 and 814 sandwiching the ridge portion. It becomes larger than the Al mixed crystal ratio,
The side surface 816 has a refractive index of the upper portion 821 and the portion 8
It becomes smaller than 15.

Further, in Example 7, since there was no current blocking layer made of GaAs, there was no light absorption, and thereby a lower threshold current and a higher differential efficiency could be obtained. In this example, the fundamental transverse mode oscillation was stably performed even when the output operation was performed at 200 mw.

Also in this embodiment, as in the case of the third embodiment, the conductivity type of the side surface portion 816 and the portion 8 are formed by doping the third cladding layer 89 with an amphoteric impurity such as Si.
The conductive type of 15 can be configured to be different, and thus the current constriction width can be further narrowed as in the third embodiment.

In each of the examples, the first clad layer and the second clad layer which form the laminated portion for light emission are A in the growth direction.
A structure in which the mixed crystal ratio is changed, for example, a SCH (Separate Confinement Heterostructure) structure including an optical guide layer, or a GRIN-SCH (Graded Index Separat)
e Confinement Heterostructure) structure.
Further, the active layer may have a quantum well structure.

[0070]

According to the semiconductor laser device of the present invention, since the refractive index type waveguide based on the effective refractive index effectively acts on the fundamental transverse mode, the semiconductor laser which has a low threshold current and can oscillate with high efficiency. An element can be provided.

Further, according to the semiconductor laser device of the present invention, a stable basic transverse mode oscillation can be obtained without high-order transverse mode oscillation even when operating at high output, and a highly reliable semiconductor laser device is provided. be able to.

According to the manufacturing method of the present invention, the semiconductor laser device of the present invention can be easily manufactured by utilizing the difference in plane orientation. Further, the semiconductor laser device of the present invention can be manufactured by two growth steps.

[Brief description of drawings]

FIG. 1 is a diagram illustrating a manufacturing process of a semiconductor laser device according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a state in which an AlGaAs layer is laminated on surfaces having different plane orientations.

FIG. 3 is a schematic view showing a semiconductor laser device of Example 2 of the present invention.

FIG. 4 is a schematic view showing a semiconductor laser device of Example 3 of the present invention.

FIG. 5 is a schematic view showing a semiconductor laser device of Example 4 of the present invention.

FIG. 6 is a schematic view showing a semiconductor laser device of Example 5 of the present invention.

FIG. 7 is a schematic diagram showing a semiconductor laser device of Example 6 of the present invention.

FIG. 8 is a schematic diagram showing a semiconductor laser device of Example 7 of the present invention.

FIG. 9 is a vertical sectional view of a conventional semiconductor laser device.

[Explanation of symbols]

1, 31, 41, 51, 61, 71, 81 Substrate 2, 32, 42, 52, 62, 72, 82 First clad layer 3, 33, 43, 53, 63, 73, 83 Active layer 4, 34, 44, 54, 64, 74, 84 Second clad layer 9, 39, 49, 59, 69, 79, 89 Third clad layer 112, 312, 412, 512, 612 Stripe groove 113, 313, 413, 513, 613 Stripe groove side surfaces 114, 214, 314, 414, 514 Stripe groove bottoms 115, 215, 315, 415, 515 Central part 116, 216, 316, 416, 516, 616, 7
16 Sides 720, 820 Ridge

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shinji Kaneiwa 22-22 Nagaike-cho, Abeno-ku, Osaka-shi, Osaka Within Sharp Corporation (72) Masafumi Kondo 22-22 Nagaike-cho, Abeno-ku, Osaka-shi, Osaka Within Sharp Corporation (72) Inventor Toshio Hata 22-22 Nagaike-cho, Abeno-ku, Osaka-shi, Osaka Inside Sharp Corporation (72) Inventor Ken Obayashi 22-22 Nagaike-cho, Abeno-ku, Osaka-shi, Osaka Sharp Corporation Within

Claims (8)

[Claims] 1. An active layer (y is 0) made of Al _y Ga _{1 -y} As.
1 inclusive) in the vertical direction on both sides of the first cladding layer made of _{Al x Ga 1-x As (} x is 0 or more and 1 or less) and the Al _z Ga _1-z
A stripe groove for current confinement is formed between a light emitting layered portion sandwiched by a second cladding layer made of As (z is 0 or more and 1 or less) and two current blocking layers that are separated from each other. Al _w Ga _1-w A is formed on the current blocking layer including the stripe groove.
and a current confinement mechanism portion including a third clad layer (w is greater than 0 and less than 1) made of s on a GaAs substrate and above the bottom of the stripe groove in the third clad layer. A semiconductor laser device having a refractive index higher than that of the portions above both side surfaces of the stripe groove. 2. The semiconductor laser device according to claim 1, wherein in the third cladding layer, a conductivity type of a portion above the bottom of the stripe groove is different from a conductivity type of a portion above both side surfaces of the stripe groove. . 3. An active layer made of Al _y Ga _1-y As (y is 0).
1 inclusive) in the vertical direction on both sides of the first cladding layer made of _{Al x Ga 1-x As (} x is 0 or more and 1 or less) and the Al _z Ga _1-z
A stripe groove for current constriction is formed between a light emitting layered portion sandwiched by a second cladding layer made of As (z is 0 or more and 1 or less) and two current blocking layers that are separated from each other. Al _w Ga _1-w A is formed on the current blocking layer including the stripe groove.
A method of manufacturing a semiconductor laser device, comprising: a current confinement mechanism portion having a third cladding layer (w is greater than 0 and less than 1) made of s on a GaAs substrate. A step of forming the stripe groove, the bottom surface orientation of the stripe groove being (100) and the surface orientations of both side surfaces thereof being (n11) (n is 1 or more and 8 or less), on the current blocking layer including the stripe groove. By laminating a third clad layer, the current confinement mechanism in which the refractive index of the portion of the third clad layer above the bottom of the stripe groove is higher than the refractive index of the portions above both side surfaces of the stripe groove. A method of manufacturing a semiconductor laser device, the method including a step of forming a portion. 4. The method of manufacturing a semiconductor laser device according to claim 3, wherein the third cladding layer is formed by doping an amphoteric impurity. 5. An active layer made of Al _y Ga _1-y As (y is 0).
A first clad layer (x is 0 or more and 1 or less) made of Al _x Ga _1-x As on both sides in the vertical direction and an Al _z Ga _1-z As having a ridge portion for current confinement and the cladding layer (z is 0 or more and 1 or less) and de sandwiched therebetween comprising laminating portion for light emitting, first made of Al _w Ga _1-w as on the second clad layer containing at least both side surfaces of the ridge portion 3 clad layer (w is greater than 0 and less than 1) on a GaAs substrate, and the refractive index of the ridge portion is a refraction portion of the third clad layer above both side surfaces of the ridge portion. Semiconductor laser device with a higher rate. 6. The semiconductor laser device according to claim 5, wherein a conductivity type of the ridge portion is different from a conductivity type of portions of the third cladding layer above both side surfaces of the ridge portion. 7. An active layer (y is 0) made of Al _y Ga _1-y As.
A first clad layer (x is 0 or more and 1 or less) made of Al _x Ga _1-x As on both sides in the vertical direction and an Al _z Ga _1-z As having a ridge portion for current confinement and the cladding layer (z is 0 or more and 1 or less) and de sandwiched therebetween comprising laminating portion for light emitting, first made of Al _w Ga _1-w as on the second clad layer containing at least both side surfaces of the ridge portion A method for manufacturing a semiconductor laser device, comprising: a GaAs substrate, and 3 clad layers (w is greater than 0 and less than 1), wherein both side surfaces of the ridge portion have a surface orientation of (n11) (n is 1 or more and 8 or less). The following) and the plane orientation of the second clad layer portions on both sides sandwiching the ridge portion is set to (100), then a third clad layer is formed on the second clad layer, and the refractive index of the ridge portion is It is larger than the refractive index of the portion above both side surfaces of the ridge portion of the third cladding layer. Method for manufacturing a semiconductor laser device. 8. The method of manufacturing a semiconductor laser device according to claim 7, wherein the third cladding layer is formed by doping an amphoteric impurity.