JPH07297487A - Semiconductor laser element - Google Patents

Abstract

PURPOSE:To provide a Group II-Vl semiconductor laser of low threshold current, high output and low noise characteristics. CONSTITUTION:This semiconductor laser element has double heterojuction structure composed of a light-emitting active layer 4 held between light wave guide layers 3, 5, and the light-emitting active layer 4 has a quantum well structure, and the light wave guide layer 5 forms a refractive index wave guide ridge stripe structure for controlling a lateral mode, and the width of the upper part of a ridge stripe is narrower than the bottom part thereof, and a laser-bean- transmitting current constricting layer 7 and a laser beam absorbing current constricting layer 8 are provided outside the ridge stripe. A threshold current is 50 to 60mA under the continuous operating condition at 25 deg.C, and an asymetrical coating element in which the reflection power of the front face and the back face is 10%, 90% operates in a lateral mode up to the light output of not less than 40%. A light output in which self-oscillation is obtained was able to be adjusted up to l0mW to 49mW by the current constricting layer 7. When a return light quantity was 5X, A noise (RIN) level was in the low range of -125 to -140dB/Hz. The oscillation wavelength of 520 to 530nm was obtained at the time of the light output of 20mW.

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 II-VI group semiconductor laser device which emits a laser beam of a short wavelength suitable for a light source for optical information terminals or optical application measurement.

[0002]

2. Description of the Related Art It is desirable that a light source used for an optical information terminal such as an optical disc of high integration and high density recording has a short wavelength. Further, it is desirable to perform self-excited oscillation in order to reduce noise. It is known that a II-VI group semiconductor laser is theoretically preferable as a short wavelength semiconductor laser device. However, a practical II-VI group semiconductor laser with high output, low noise and self-sustained pulsation at room temperature has not been realized. Conventionally,
In a II-VI group semiconductor laser device, CdZnSe /
An attempt has been made to fabricate a green semiconductor laser having a stripe structure and a current confinement structure by a ZnS semiconductor burying layer using a MgZnSSe-based material, and it is known that pulse oscillation operation is realized at room temperature. Physics Letters 1993, 63
Vol. 2315 (Appl. Phys. Lett., 6
3 (1993) 2315).

[0003]

The green CdZnSe / MgZnSSe system II-VI group semiconductor laser described in the above document has a high current confinement structure because a single ZnS layer is used as a buried layer. It does not have a refractive index waveguide structure capable of stable transverse mode control up to the output, and only an output of 10 mW or less is obtained. Therefore, it cannot be put to practical use in an optical disk device that requires about 30 mW. In addition, the refractive index in the lateral direction cannot be set appropriately, and the waveguide structure does not have stable self-sustained pulsation. Moreover, since the ZnS burying layer is a polycrystal and has a large lattice constant difference of about -4% with respect to the GaAs substrate, crystal defects are easily formed and guided light loss due to light scattering cannot be reduced. .

An object of the present invention is to provide a semiconductor laser which has stable self-sustained pulsation up to a high output region, operates at a low threshold current, and has a low noise characteristic. It is another object of the present invention to provide a II-VI group semiconductor laser in which self-excited oscillation is stably maintained up to a high output region and which operates at a low threshold current.

[0005]

In order to achieve the above object, the semiconductor laser device of the present invention comprises an active layer having a forbidden band width smaller than the forbidden band width of the optical waveguide layer sandwiched between two optical waveguide layers. In the semiconductor laser having the double heterojunction structure, at least one of the optical waveguide layers has a ridge stripe structure in which a cross section perpendicular to the optical axis direction has a trapezoidal central part and flat bottom parts on both sides, At least a first current confinement layer transparent to the laser light on the optical waveguide layer on the side of the ridge stripe, and a second current confinement layer absorbing the laser light on the upper side of the first current confinement layer. A two-step buried layer was provided. The thickness, width and materials of the ridge stripe structure, the first and second current confinement layers are set so that the difference in refractive index in the lateral direction of the active layer is in the range of 1 × 10 ³ to 8 × 10 ³ Then, the transverse mode of the optical waveguide layer is controlled to form a refractive index waveguide ridge stripe structure in which self-sustained pulsation continues.
The trapezoid of the ridge stripe structure has an upper side width of 2 to 3 μ.
m, the width of the base is set in the range of 4 to 6 μm, the film thickness of the skirt is 0.15 to 0.35 μm, and the film thickness of the first current constriction layer is 0.2 to 0.4 μm. The thickness of the second current constriction layer is set in the range of 0.8 to 1.3 μm. Further, the carrier concentration of each of the first and second current confinement layers is 5 ×
10 ^{17 to} 2 × 10 ¹⁸ cm to ³ and 1 × 10 ¹⁸ to 1 × 10 ¹⁹
The range was set to cm ~ ³ .

Preferably, the active and buried layers are II-VI.
The mixed crystal material of the II-VI group semiconductor is a material having a composition that lattice-matches with the semiconductor substrate. The active layer has a single or multiple quantum well structure. Also,
In the II-VI group semiconductor laser, when the semiconductor substrate is GaAs, a preferable material configuration is to use the quantum well structure of the light emitting active layer as a ZnSSe or MgZnSSe quantum barrier layer together with a CdZnSe compressive strain quantum well layer. A ZnSSe or MgZnSSe layer and a ZnSTe layer are provided on the first and second current confinement layers, respectively. When the semiconductor substrate is InP, the quantum well structure of the light emitting active layer is CdZnSe or ZnSeTe tensile strained quantum well layer, and MgZnSe or Mg is used.
The first and second ZnSeTe quantum barrier layers are used as
Of MgZnSe or MgZnS respectively
An eTe layer and a ZnSTe layer are used.

[0007]

In the refractive index waveguide structure capable of self-sustained pulsation in the longitudinal multimode, it is necessary to set the refractive index difference in the lateral direction of the active layer relatively smaller than that in the longitudinal single mode waveguide structure. Conventionally, it was formed by providing a large thickness of the optical waveguide layer on the outside of the stripe. At this time, there arises a problem that the difference in refractive index in the lateral direction of the active layer becomes small and the reactive current that does not contribute to laser oscillation rises in the lateral direction of the optical waveguide layer of the stripe structure. Therefore, in the present invention, the buried layer is provided with at least two stages of a first current confinement layer having a larger forbidden band width than the active layer and transparent to laser light and a second current confinement layer having a smaller forbidden band width and absorbing laser light. With the embedded structure provided, the current confinement layer that is transparent to the laser light is first provided in the optical waveguide layer, so that the refractive index difference in the lateral direction of the active layer is set small to enable self-oscillation. The reactive current can be reduced, and a lower threshold operation than the conventional one is achieved.

Further, the conventional semiconductor laser has a problem that it is impossible to increase the output power of the fundamental transverse mode as compared with the waveguide structure having a large difference in refractive index in the lateral direction of the active layer. As an example, when an active layer with a single or multiple quantum well structure with a small change in refractive index due to carrier injection is used, the built-in refractive index difference is kept large, and the fundamental transverse mode is controlled to a high carrier injection region to achieve bulk activation. Higher output can be achieved than in the case of layers. In other words, in the quantum well structure active layer, the kink level, which is the optical output that makes the transverse mode unstable, can be improved, so that a higher output of the fundamental transverse mode is achieved.

Furthermore, if the thickness of the current confinement layer, which is the first buried layer, is set appropriately, a weak waveguide structure can be designed in which stable self-sustained pulsation can be obtained, and the difference in the refractive index in the lateral direction of the active layer can be obtained. It could be set in the range of 1 × 10 ³ to 8 × 10 ³ Further, the self-sustained pulsation was obtained from the optical output of 2 mW, and the maximum optical output obtained by the self-sustained pulsation could be adjusted in the range of 10 mW to 60 mW by the film thickness of the first current confinement layer. As described above, it is possible to form a refractive index waveguide structure in which self-excited oscillation is stably maintained up to a high output region of 50 mW or more in the fundamental transverse mode, achieve low threshold operation with suppressed reactive current, and self-excited oscillation. At the time of the optical output that obtains, a low noise characteristic of a noise (RIN) level of −125 to −140 dB / Hz was obtained.

[0010]

【Example】

<Embodiment 1> FIG. 1 is a sectional structural view of an embodiment of a semiconductor laser device according to the present invention. As shown, the n-side electrode 11 of the AuGeNi layer, the n-type GaAs substrate 1, and the
An n-type ZnSe buffer layer 2, an n-type MgZnSSe optical waveguide layer 3, and an undoped CdZnSe / ZnSSe strained multiple quantum well structure active layer 4 are stacked, and a trapezoidal flat layer having a central part with a narrow upper side and a wide base on the upper surface of the active layer 4. A ridge stripe structure p-type MgZnS having a cross-sectional shape formed above
The Se optical waveguide layer 5 is laminated. On the upper side of the trapezoid of the optical waveguide layer 5, a p-type ZnSSe buffer optical waveguide layer 6 is formed on the extension of the trapezoid. On the lateral side of the ridge stripe structure, that is, on the side of the trapezoid above the bottom of the ridge stripe structure, n-type ZnSSe transparent to laser light is provided.
The current confinement layer 7 is formed outside the upper end of the trapezoid so as to have a temporary increase in thickness. A p-type ZnSTe buffer / light absorption layer 8 is formed on the trapezoidal upper surface and the upper surface of the current confinement layer 7, and the upper portion of the current confinement layer 7 serves as a current confinement layer that absorbs laser light. The upper surface of the current constriction layer 8 is flat, and the p-type ZnSTe / ZnTe contact layer 9 and the p-side electrode 10 of PdPtAu are formed on the flat surface.

The manufacturing process of the semiconductor laser device of this embodiment will be described. Cl-doped n-type ZnS is formed on the n-type GaAs substrate 1 having a substrate plane orientation that is 5 ° off from the (100) plane.
e buffer layer 2 (layer thickness d = 0.1 μm, carrier concentration n _D = 1 × 10 ¹⁸ cm ³ ), Cl-doped n-type Mg _y Zn
_1-y S _z Se _1-z optical waveguide layer 3 (d = 1.5 μm, n _D = 5 ×
10 ¹⁷ cm- ³ , y = 0.10-0.12, z = 0.12-
0.15), undoped Cd _x Zn _1-x Se / ZnS _z Se
_1-z strained quantum well structure active layer 4 (ZnS _z Se _1-z quantum barrier layer (d = 4 nm, z = 0.06 to 0.08)) 2 periods and Cd
_x Zn _1-z Se compressive strain quantum well layer (d = 6 nm, x = 0.
1) 3 period and ZnS _z Se _1-z optical separate confinement layer on both sides (d = 30nm, z = 0.06~0.08 )), N -doped p-type _{Mg y Zn 1-y S z} Se 1- _z optical waveguide layer 5 (d = 1.
2 μm, n _A = 4 to 7 × 10 ¹⁷ cm to ³ , y = 0.10
0.12, z = 0.12 to 0.15), N-doped p-type Zn
S _Z Se _1-z optical waveguide layer 6 (d = 0.2 μm, n _A = 8 × 10
¹⁷ to 1 × 10 ¹⁸ cm to ³ and z = 0.06 to 0.08) are sequentially grown at a growth temperature of 300 by the molecular beam epitaxy (MBE) method.
Epitaxially grows at ℃.

After that, a SiN insulating film (d = 0.2 to 0.3)
of 0.15 to 0.20 μm by photolithography and chemical etching.
Layers 6 and 5 are removed to the remaining portion to form a ridge stripe mesa (width 4 to 6 μm). Next, with the SiN mask left, gas source molecular beam epitaxy (G
The n-type ZnS _Z Se _1-z current confinement layer 7 (d = 0.2 to 0.2) is formed by the SMBE method or the metal organic chemical vapor deposition (MOCVD) method.
0.4 μm, n _D = 5 × 10 ¹⁷ to 1 × 10 ¹⁸ cm to ³ , z =
0.06 to 0.08) is selectively grown to fill the stripe structure.

Then, after removing the SiN mask by etching, the N-doped p-type ZnSαTe _1- α buffer / light absorbing layer 8 (d = 1.5 to 3.0 μm, n _A = 1 to 3) by MBE method.
× 10 ¹⁸ cm ~ ³ , α = 0.62 ~ 0.64), N-doped p
Type ZnSαTe _1- α layer 9 (d = 20 to 50 nm, n _A = 3)
× 10 ^{18 to} 2 × 10 ¹⁹ cm to ³ , α gradually decreases from 0.63 to 0 toward the electrode 10 from the layer 7, and the surface in contact with the electrode 10 has an N-doped p-type ZnTe contact layer (n _A = 2
X 10 ¹⁹ cm ³ )) is epitaxially grown so as to be buried evenly in the stripe structure. After this, p
Side electrode PdPtAu10 and n-side electrode AuGeNi11
Is vapor-deposited and cleaved and scribed to cut out into the shape of the semiconductor laser device shown in the sectional view of FIG.

In this example, the threshold current of the uncoated device having a cavity length of 600 μm was 5 under the continuous operation condition of 25 ° C.
0 to 60 mA, and the reflectance of the front and rear surfaces is 10 each
% And 90%, it was confirmed that the fundamental transverse mode was stably operated up to an optical output of 40 mW or more. Further, by adjusting the film thickness of the current confinement layer 7 within the above range, the light output range in which self-sustained pulsation can be obtained could be controlled. Self-sustained pulsation was obtained from an optical output of 2 mW, and the maximum optical output at which self-sustained pulsation was obtained could be adjusted from 10 mW to 40 mW depending on the film thickness of the current confinement layer 7. In the optical output range where self-sustained pulsation is obtained, the noise (RIN) level is -125 to -140 even when the amount of returned light is 5%.
It was in the low range of dB / Hz. The oscillation wavelength is the optical output 2
520-530 nm was obtained at 0 mW.

<Embodiment 2> FIG. 2 is a sectional structural view of another embodiment of the semiconductor laser device according to the present invention.

In the figure, the same functions as those of the embodiment of FIG.
The material parts are given the same numbers. The difference from Example 1 is that
N-doped p-type ZnSαTe _1- α is formed on the upper center of the ridge structure.
The buffer layer 8 is added, and the current confinement layer 7 is the buffer layer 8.
Is formed while increasing the thickness from the upper surface to the lateral side. An n-type ZnSTe light absorption / current confinement layer 12 is laminated on the upper surface of the current confinement layer 7. The upper surface of the light absorption / current constriction layer 12 is flush with the upper surface of the buffer layer 8.

The manufacturing process of the second embodiment will be described. (10
N-type GaA having a substrate plane orientation that is 5 ° off from the (0) plane
Using the s substrate 1, the layers 6 are sequentially epitaxially grown by the MBE method in the same manner as in the first embodiment. Then, N-doped p-type ZnSαTe _1- α buffer layer 8 (d = 0.1 to 0.1.
2 μm, nA = 1 to 3 × 10 ¹⁸ cm ~ ³ , α = 0.62 to 0.
64) and then, by photolithography and chemical etching, the layers 8, 6, and 5 are removed until the layer 5 remains at 0.15 to 0.20 μm, and the ridge is formed in the same manner as in Example 1. Create a stripe structure. Next, SiN
The n-type ZnS _Z Se _1-Z current confinement layer 7 (d = 0.2 to 0.2) is formed by the GSMBE method or the MOCVD method while leaving the mask.
0.4 μm, n _D = 5 × 10 ¹⁷ to 1 × 10 ¹⁸ cm to ³ , z =
0.06 to 0.08), n-type ZnSαTe _1- α light absorption and current confinement layer 8 (d = 0.8 to 1.0 μm, nA = 1 to 3 × 10)
¹⁸ cm ~ ³ , α = 0.62 ~ 0.64) is selectively grown to bury the stripe structure flatly. Next, after removing the SiN mask by etching, the device shown in the sectional view of FIG.

In this example, the threshold current of the uncoated element having a cavity length of 600 μm is 4 under the continuous operation condition of 25 ° C.
0 to 50 mA, the reflectance of the front and rear surfaces is 10% -90
5% light output by applying asymmetric coating
It was confirmed that the device operates stably in the basic transverse mode up to 0 mW or more. Further, by adjusting the film thickness of the current confinement layer 7 within the above range, the light output range in which self-sustained pulsation can be obtained could be controlled. The self-sustained pulsation was obtained from an optical output of 2 mW, and the maximum optical output at which self-sustained pulsation was obtained could be adjusted from 10 mW to 50 mW depending on the film thickness of the current confinement layer 7. In the light output range where self-sustained pulsation can be obtained, the noise (RIN) level was in the low range of −125 to −140 dB / Hz even when the amount of returned light was 5%. The oscillation wavelength is 5 when the optical output is 30 mW.
20-530 nm was obtained.

<Third Embodiment> FIG. 3 is a sectional view showing the structure of a semiconductor laser device according to a third embodiment of the present invention. As shown, the n-side electrodes 11, n of the AuGeNi layer are sequentially arranged from the bottom.
-Type InP substrate 13, n-type MgSe buffer layer 14, n-type MgZnSe optical waveguide layer 15 and undoped CdZnSe
/ ZnSeTe strained multiple quantum well structure active layer 16 is laminated, and a ridge stripe structure p-type MgZnSSe optical waveguide having a cross-sectional shape in which a trapezoid with a central upper part and a wider base is formed on the upper surface of the active layer 16 on a flat layer. On the wave layer 17 and the upper side of the trapezoid, a p-type ZnSeTe optical waveguide layer 18 and a p-type ZnSTe buffer layer 19 are further laminated. On the lateral side of the trapezoid, an n-type MgZnSe current confinement layer 20 transparent to laser light and an n-type ZnSTe light absorption / current confinement layer 21 that absorbs laser light are stacked in this order from the bottom. A top surface of the light absorption / current constriction layer 21 and a top surface of the buffer layer 19 form a plane, and a p-type ZnSTe / ZnTe contact layer 22 and a p-side electrode PdPtAu 23 are sequentially stacked on the plane.

The manufacturing process of this embodiment will be described. First,
A Cl-doped n-type MgSe buffer layer 14 (d = 0.1 μm, n _D = 1 × 10 ¹⁸ cm) was used by using an n-type InP substrate 13 having a substrate plane orientation that was off by 5 ° from the (100) plane.
~ ^3), Cl-doped n-type Mg _Z Zn _1-Z Se optical waveguide layer 15
(D = 1.5 μm, n _D = 5 × 10 ¹⁷ cm ~ ³ , z = 0.8
8 to 0.92), undoped Cd _X Zn _1-X Se / ZnS
e _Y Te _1-Y strained quantum well structure active layer 16 (ZnSe _Y Te
_1-Y quantum barrier layer (d = 4 nm, y = 0.45 to 0.50)
1 layer and Cd _X Zn _1-X Se tensile strain quantum well layer (d = 12n
m, x = 0.3) 2 periods and ZnSe _Y Te on both sides
_1-Y light separation confinement layer (d = 30 nm, y = 0.45
0.50)), N-doped p-type Mg _Z Zn _1-Z Se optical waveguide layer 17 (d = 1.2μm, nA = 4~5 × 10 17 cm ~ 3, z
= 0.88 to 0.92), N-doped p-type ZnSe _Y Te _1-Y
Optical waveguide layer 18 (d = 0.2 μm, nA = 8 × 10 ¹⁷ cm
~ ³ , y = 0.45 to 0.50), N-doped p-type ZnSαT
e ₁₋ α buffer layer 19 (d = 0.1 μm, nA = 1 to 3 ×)
10 ¹⁸ cm ³ and α = 0.30 to 0.32) are sequentially epitaxially grown by the MBE method. Then, after depositing a SiN insulating film (d = 0.2 to 0.3 μm), the layer 17 is reduced to 0.1 by photolithography and chemical etching.
Layer 19, layer 18, and layer 1 up to the remaining portion of 5 to 0.20 μm
7 is removed, and the ridge stripe mesa (width 4 to 6 μm
m) is formed. Next, while leaving the SiN mask, G
N-type Mg _Z Zn _1-Z by SMBE method or MOCVD method
Se current confinement layer 20 (d = 0.2 to 0.4 μm, n _D = 5
× 10 ¹⁷ to 1 × 10 ¹⁸ cm to ³ , z = 0.88 to 0.9
2), n-type ZnSαTe _1- α light absorption and current confinement layer 21
(D = 0.8 to 1.0 μm, nA = 1 to 3 × 10 ¹⁸ cm ~
³ , α = 0.30 to 0.32) is selectively grown to bury the stripe structure flatly. Next, after removing the SiN mask by etching, the N-doped p-type ZnSαTe _1- α is formed by the MBE method.
Layer 22 (d = 20 to 50 nm, nA = 3 × 10 ¹⁸ to 2 × 1)
0 ¹⁹ cm to ³ , α is 0.3 from the layer 19 toward the electrode 23.
It gradually decreases from 0 to 0, and the surface in contact with the electrode 23 is an N-doped p-type ZnTe contact layer (nA = 2 × 10 ¹⁹ cm ~ ³ )
And) is epitaxially grown. After that, the p-side electrode PdPtAu23 and the n-side electrode AuGeNi24 are vapor-deposited, and cleaved and scribed to cut out into the shape of the element shown in the sectional view of FIG.

In this embodiment, the threshold current of the uncoated device having a cavity length of 600 μm is 4 under the continuous operation condition of 25 ° C.
0 to 50 mA, the reflectance of the front and rear surfaces is 10% -90
5% light output by applying asymmetric coating
It was confirmed that the device operates stably in the basic transverse mode up to 0 mW or more. Further, by adjusting the film thickness of the current confinement layer 20 within the above range, the light output range in which self-sustained pulsation can be obtained could be controlled. The self-sustained pulsation was obtained from the optical output of 2 mW, and the maximum optical output at which the self-sustained pulsation was obtained could be adjusted from 10 mW to 50 mW by the film thickness of the current confinement layer 20. In the light output range where self-sustained pulsation can be obtained, the noise (RIN) level was in the low range of −125 to −140 dB / Hz even when the amount of returned light was 5%. The oscillation wavelength was 520 to 530 nm when the optical output was 30 mW.

The embodiment of the present invention has been described above.
The present invention is not limited to the above embodiment. For example, in the embodiment, the substrate plane orientation is 5 ° off from (100), but the substrate plane orientation is 0 from the (100) plane.
The crystal plane may be off by about 54.7 °. Although the active layer has a quantum well structure, it may have a bulk structure.

[0023]

When the thickness of the current confinement layer which is the first buried layer and is transparent to the laser beam is set appropriately, the self-sustained pulsation can be stably obtained. ³
It is possible to set a weak waveguide structure in the range from 8 × 10 ³ to 8 × 10 ³ . According to the present invention, an II-VI semiconductor laser having a single or multiple quantum well structure active layer introduced with compressive strain or tensile strain is provided with a buried current confinement difference layer in at least two stages, and is transparent to laser light. If the film thickness of the current confinement layer is properly set, stable operation up to a high output region of 50 mW or more in the fundamental transverse mode is achieved, and self-excited oscillation can be obtained from an optical output of 2 mW.
In addition, it is possible to control the optical output that can obtain self-sustained pulsation in the low output range of 2 mW to the high output range of 60 mW. At the time of optical output where self-excited oscillation is obtained, the noise (RIN) level is -125 to -140 dB / H even when the amount of returned light is 5%.
It could be suppressed to a low range of z. As a result, the semiconductor laser of the present invention has low noise and high output as a memory writing / erasing light source for a magneto-optical disk or a phase change optical disk, and sufficiently satisfies the element characteristics required for the system.

[Brief description of drawings]

FIG. 1 is a sectional configuration diagram of an embodiment of a semiconductor laser device according to the present invention.

FIG. 2 is a sectional configuration diagram of another embodiment of the semiconductor laser device according to the present invention.

FIG. 3 is a sectional configuration diagram of still another embodiment of the semiconductor laser device according to the present invention.

[Explanation of symbols]

1: n-type GaAs substrate 2: n-type ZnSe buffer layer 3: n-type MgZnSSe optical waveguide layer 4: undoped CdZnSe / ZnSSe strained multiple quantum well structure active layer 5: p-type MgZnSSe optical waveguide layer 6: p-type ZnSSe optical waveguide layer 7: n-type ZnSSe current constriction layer 8: p-type ZnSTe buffer / light absorption layer 9: p-type ZnSTe / ZnTe contact layer 10: p-side electrode PdPtAu 11: n-side electrode AuGeNi 12: n-type ZnSTe light absorption / current confinement layer 13 : N-type InP substrate having a substrate plane orientation off by 5 ° from the (100) plane 14: n-type MgSe buffer layer 15: n-type MgZnSe optical waveguide layer 16: undoped CdZnSe / ZnSeTe strained multiple quantum well structure active layer 17: p -Type MgZnSe optical waveguide layer 18: p-type ZnSeTe optical waveguide layer 19: p-type ZnS e Buffer layer 20: n-type MgZnSe current confinement layer 21: n-type ZnSTe light absorbing and current confinement layer 22: p-type ZnSTe / ZnTe contact layer 23: p-side electrode PdPtAu 24: n-side electrode AuGeNi

Claims (9)

[Claims] 1. A semiconductor laser having a double heterojunction structure, comprising an active layer sandwiched between two optical waveguide layers on a semiconductor substrate and having a bandgap smaller than the forbidden band width of the optical waveguide layers. At least one of the optical waveguide layers has a ridge stripe structure in which a cross-sectional shape perpendicular to the optical axis direction is a trapezoid at the center and flats at the skirts on both sides,
At least a first current confinement layer transparent to the laser light on the optical waveguide layer on the side of the ridge stripe, and a second current confinement layer absorbing the laser light on the upper side of the first current confinement layer. A semiconductor laser device having a two-step buried layer. 2. The semiconductor laser device according to claim 1, wherein the active layer and the first and second current confinement layers are II-VI.
A semiconductor laser device characterized by being a group semiconductor. 3. The semiconductor laser device according to claim 2, wherein the semiconductor substrate is GaAs, and the active layer has a quantum well structure of CdZnSe and a compressive strain quantum well layer and ZnSSe.
Or a quantum barrier layer of MgZnSSe.
The current constriction layer of ZnSSe or MgZnSSe layer shoulder, and the second current confinement layer of ZnSTe layer,
The mixed crystal material forming the buried layer is G of the semiconductor substrate.
A semiconductor laser device characterized by being set to a composition of a material lattice-matched with aAs. 4. The semiconductor laser device according to claim 3, wherein the semiconductor substrate is InP and the active layer is CdZn.
Se or ZnSeTe tensile strain quantum well layer and MgZnSe
Or a MgZnSeTe quantum barrier layer,
The current confinement layer is made of MgZnSe or MgZnSeTe layer, the second current confinement layer is made of ZnSTe layer, and the mixed crystal material forming the buried layer is set to the composition of the material lattice-matched with InP of the semiconductor substrate. A semiconductor laser device characterized by the above. 5. The semiconductor laser device according to claim 1, 2, 3, or 4, wherein the active layer has a lateral refractive index difference of 1 ×.
It is set in the range of 10 to ³ to 8 × 10 to ³ , and it is set to 2 mW to 6
A semiconductor laser device having a refractive index guided fundamental transverse mode control structure in which self-sustained pulsation continues in a range of 0 mW. 6. The semiconductor laser device according to claim 1, 2, 3 or 4, wherein the first current confinement layer is 5 × 10 ¹⁷ to 2 ×.
A semiconductor laser device characterized in that a carrier concentration in the range of 10 ¹⁸ cm ³ is set, and a carrier concentration in the second current confinement layer is set in the range of 1 × 10 ¹⁸ -1 × 10 ¹⁹ cm- ³ . 7. The semiconductor laser device according to claim 1, 2, 3 or 4, wherein the film thickness of the optical waveguide layer in the flat portion of the ridge stripe structure is in the range of 0.15 to 0.35 μm. The thickness of the current confinement layer is in the range of 0.2 to 0.4 μm, and the thickness of the first current confinement layer is in the range of 0.8 to 1.3 μm.
A semiconductor laser device characterized by being set in a range. 8. The semiconductor laser device according to claim 1, 2, 3 or 4, wherein the width of the base of the trapezoid in the ridge stripe structure is 4 to 6 μm, and the width of the top of the trapezoid is 2 to 3 μm. A semiconductor laser device characterized by being set to. 9. The semiconductor laser device according to claim 1, wherein the semiconductor substrate has a crystal plane in which the substrate plane orientation is 0 to 54.7 ° off from the (100) plane. Semiconductor laser device.