JPH06334272A - Semiconductor laser - Google Patents

Abstract

PURPOSE:To achieve blue or green light emission using ZnMgSSe compound semiconductor as a clad layer by constituting a first clad layer, a first optical waveguide layer, an active layer, a second optical waveguide, and a second clad layer with a compound semiconductor shown by an expression and then forming the active layer to be a single quantum well layer with a specific thickness. CONSTITUTION:By forming a first clad layer 3 and a second clad layer 7 with ZnMgSSe compound semiconductor (x=0, b=0) in a compound semiconductor in an expression 1 (0<=x<1, 0<=y<1, 0<=a<1, 0<=b<1), the title semiconductor laser with SCH structure where blue or green light can be emitted using the ZnMgSSe compound semiconductor as the material of a clad layer can be achieved. Besides, an active layer 5 has a single quantum well layer 5b which is 2-20nm thick so that the title semiconductor laser has a low threshold current.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor laser, and more particularly to a semiconductor laser capable of emitting blue or green light.

[0002]

2. Description of the Related Art In recent years, in order to improve the recording density of optical discs and the resolution of laser printers, there is an increasing demand for semiconductor lasers capable of emitting light at short wavelengths, and research aimed at realizing them has been made. It is active.

II-VI group compound semiconductors are attracting attention as materials used for producing semiconductor lasers capable of emitting light at such short wavelengths. And recently,
It has been reported that a blue- or green-emitting semiconductor laser with an oscillation wavelength of 490 to 520 nm could be realized by using a ZnSSe-based compound semiconductor, which is one of II-VI group compound semiconductors, as a material for the cladding layer ( For example, Nikkei Electronics, April 27, 1992.
Japanese issue, no. 552, pages 90-91).

[0004]

As described above, ZnS
Although a semiconductor laser capable of emitting blue or green light has been realized by using a Se-based compound semiconductor as a material for the cladding layer, a semiconductor laser capable of emitting blue or green light by using a ZnMgSSe-based compound semiconductor as a material for the cladding layer has been realized. Realizing a laser has been difficult.

Therefore, the object of the present invention is to obtain ZnMgSS.
An object of the present invention is to provide a semiconductor laser which uses an e-based compound semiconductor as a material for a cladding layer and can emit blue or green light and has a low threshold current.

[0006]

A DH structure (Double Heterostructur) in which a ZnSe active layer is sandwiched between an n-type ZnMgSSe cladding layer and a p-type ZnMgSSe cladding layer
e), a n-type ZnMgSSe optical waveguide layer and a p-type ZnMgSS layer above and below the ZnCdSe active layer.
e n-type ZnMgS and the upper and lower sides of the n-type ZnMgS
SCH structure (Separated Confinement Heterostructu) sandwiched between Se clad layer and p-type ZnMgSSe clad layer
FIG. 13 shows the results obtained by calculating the dependence of the threshold current density (J _th ) on the thickness of the active layer for a semiconductor laser having re). However, the resonator length L of both the semiconductor laser having the DH structure and the semiconductor laser having the SCH structure was 500 μm, and the internal loss α _in was 10 cm ⁻¹ . In addition, regarding the semiconductor laser having the DH structure, the refractive index difference Δ between the ZnSe active layer and the n-type ZnMgSSe cladding layer and the p-type ZnMgSSSSe cladding layer is Δ.
The calculation was performed for two cases where n was 0.13 and 0.2. On the other hand, for the semiconductor laser having the SCH structure, the ZnCdSe active layer and the n-type Zn are used.
MgSSe refractive index difference between the optical waveguide layer and p-type ZnMgSSe optical waveguide layer [Delta] n _g is 0.1, ZnCdSe active layer and the n-type ZnMgSSe cladding layer and p-type ZnMgS
The refractive index difference Δn _c with the Se clad layer was 0.2, and the thickness W _g of each of the n-type ZnMgSSe optical waveguide layer and the p-type ZnMgSSe optical waveguide layer was 75 nm.

As can be seen from FIG. 13, in the semiconductor laser having the DH structure, the active layer has a thickness of 30-4.
The threshold current density has a minimum value at 0 nm, and when the thickness of the active layer is in the vicinity of the thickness giving this minimum value,
That is, the threshold current density becomes sufficiently low when the thickness of the active layer is 15 to 60 nm. On the other hand, in the semiconductor laser having the SCH structure, the thickness of the active layer is about 10
up to nm, the threshold current density decreases as the thickness of the active layer decreases, and when the thickness of the active layer is 2 to 20 nm, the threshold current density becomes sufficiently low. From the above, as a material for forming a laser structure, II-
When a group VI compound semiconductor is used, in order to reduce the threshold current density in both the semiconductor laser having the DH structure and the semiconductor laser having the SCH structure, the thickness of the active layer should be made sufficiently small. Therefore, it is possible to understand the importance of increasing the carrier injection efficiency.

The importance of reducing the thickness of the active layer and increasing the carrier injection efficiency is clear from the following experimental results. That is, FIG. 14 shows ZnSS
7 shows a photoluminescence (PL) intensity decay curve obtained from a ZnSSe active layer having a thickness of 70 nm in a semiconductor laser having a DH structure in which an e active layer is sandwiched between an n-type ZnMgSSe cladding layer and a p-type ZnMgSSe cladding layer. . From the slope of the attenuation curve shown in FIG. 14, P
The time constant of the L intensity decay is about 50 psec. Since the radiative recombination lifetime of the ZnSe crystal is expected to be several nsec, it is considered that this very fast PL intensity decay with a time constant of about 50 psec is governed by the nonradiative recombination process. However, it is possible to realize laser oscillation by photoexcitation using the same sample. This is because the number of non-radiative centers in the sample is approximately the same as the number of carriers excited by the excitation light under the weak excitation condition in the PL measurement, so that the trap is saturated and laser oscillation occurs during the optical excitation under the strong excitation condition. This is due to the accumulation of enough carriers for In a semiconductor laser manufactured using a crystal containing such a trap, it is important to inject carriers into the active layer more efficiently than usual. From this point as well, II-V
It can be seen that it is effective to reduce the thickness of the active layer in order to reduce the threshold current density of the semiconductor laser using the group I compound semiconductor.

Further, according to the knowledge of the present inventor, SCH
In a semiconductor laser having a structure, when the active layer has a single quantum well structure or a double quantum well structure, the threshold current density is almost halved compared to the case where the active layer has a triple quantum well structure ( However, the thickness of the quantum well layer is the same). Therefore, it is found that it is effective to make the active layer a single quantum well structure or a double quantum well structure in order to reduce the threshold current density of the semiconductor laser having the SCH structure.

The present invention was devised as a result of further various investigations based on the above findings and investigations of the present inventor.

That is, to achieve the above object, the semiconductor laser according to the first invention of the present invention comprises a first conductivity type first cladding layer (3) laminated on a compound semiconductor substrate (1), A first optical waveguide layer (4) laminated on the first cladding layer (3), an active layer (5) laminated on the first optical waveguide layer (4), and an active layer (5) A second conductive type second clad layer (7) laminated on the second optical waveguide layer (6) and a second optical waveguide layer (6); Clad layer (3), first optical waveguide layer (4),
Active layer (5), a second optical waveguide layer (6) and a second cladding layer (7) is _{Zn 1-xy Cd x Mg y} S a Te b Se
_1-ab (where 0 ≦ x <1, 0 ≦ y <1, 0 ≦ a <
1, 0 ≦ b <1) based compound semiconductor, the active layer (5) has a single quantum well layer (5b), and the quantum well layer (5b) has a thickness of 2 to 20 nm. It is characterized by that.

The semiconductor laser according to the second invention of the present invention is the semiconductor laser according to the first invention of the present invention, wherein the first cladding layer (3) and the second cladding layer (7) are made of ZnMgSSe compound semiconductor. Consists, first
The optical waveguide layer (4) and the second optical waveguide layer (6) of
The active layer (5) is made of a Se-based compound semiconductor or a ZnSe-based compound semiconductor, and the active layer (5) is a quantum well layer made of a ZnCdSe-based compound semiconductor.

A semiconductor laser according to a third aspect of the present invention is the semiconductor laser according to the first aspect of the present invention, wherein the compound semiconductor substrate (1) is a GaAs substrate,
The first cladding layer (3) is laminated on a GaAs substrate via a buffer layer (2) made of ZnSe, and the first cladding layer (3) and the second cladding layer (7) are 0 <p ≦.
0.2, 0 <q ≦ 0.3 Zn _1-p Mg _p S _q Se _1-q
The first optical waveguide layer (4) and the second optical waveguide layer (6) are made of ZnS _u Se _1-u or Zn with 0 <u ≦ 0.1.
The active layer (5) is made of Se and has Zn of 0 <z ≦ 0.3.
_A quantum well layer made of _1-z Cd _z Se, and a bandgap difference between the quantum well layer and the first cladding layer (3) and the second cladding layer (7) is 0.25 eV or more. , The band gap difference between the first optical waveguide layer (4) and the second optical waveguide layer (6) and the quantum well layer is 0.
It is characterized by being 1 eV or more.

A semiconductor laser according to a fourth aspect of the present invention is the semiconductor laser according to the first aspect of the present invention, wherein the first cladding layer (3) and the second cladding layer (7) are made of ZnMgSSe compound semiconductor. Consists, first
The optical waveguide layer (4) and the second optical waveguide layer (6) of
The active layer (5) is composed of gSSe-based compound semiconductor and is made of Zn.
The quantum well layer is made of a Se-based compound semiconductor or a ZnSSe-based compound semiconductor.

A semiconductor laser according to a fifth aspect of the present invention is the semiconductor laser according to the first aspect of the present invention, wherein the compound semiconductor substrate (1) is a GaAs substrate,
The first clad layer (3) is laminated on a GaAs substrate via a buffer layer (2) made of ZnSe, and the first clad layer (3) and the second clad layer (7) are 0.1 ≦.
Zn _1-p Mg _{p with} p ≦ 0.4 and 0.15 ≦ q ≦ 0.45
S _q Se _1-q , wherein the first optical waveguide layer (4) and the second optical waveguide layer (6) are 0.05 ≦ p ≦ 0.15, 0.1.
Zn _1-p Mg _p S _q Se _{1-q with} ≦ q ≦ 0.2,
The active layer (5) comprises a quantum well layer made of ZnSe,
First cladding layer (3) and second cladding layer (7)
Bandgap difference between the quantum well layer and the quantum well layer is 0.25e
V or more, and the difference in bandgap between the quantum well layer and the first optical waveguide layer (4) and the second optical waveguide layer (6) is 0.1 eV or more. is there.

A semiconductor laser according to a sixth aspect of the present invention is the semiconductor laser according to the first aspect of the present invention, wherein the compound semiconductor substrate (1) is a GaAs substrate,
The first cladding layer (3) is laminated on a GaAs substrate via a buffer layer (2) made of ZnSe, and the first cladding layer (3) and the second cladding layer (7) are 0.15
Zn _1-p Mg _{p with} ≦ p ≦ 0.5 and 0.2 ≦ q ≦ 0.55
_Sq Se _1-q , and the first optical waveguide layer (4) and the second optical waveguide layer (6) are 0.1 ≦ p ≦ 0.2, 0.15 ≦
consisting of Zn _1-p Mg _p S _q Se _{1-q with} q ≦ 0.25,
The active layer (5) is ZnS _u Se with 0.01 ≦ u ≦ 0.1.
_A quantum well layer made of _1-u, and a bandgap difference between the first cladding layer (3) and the second cladding layer (7) and the quantum well layer is 0.25 eV or more; The bandgap difference between the optical waveguide layer (4) and the second optical waveguide layer (6) and the quantum well layer is 0.1 eV or more.

A semiconductor laser according to a seventh aspect of the present invention comprises a first clad layer (3) of the first conductivity type laminated on a compound semiconductor substrate (1) and a first clad layer (3). A first optical waveguide layer (4) laminated on the first optical waveguide layer, an active layer (5) laminated on the first optical waveguide layer (4), and a second optical waveguide layer laminated on the active layer (5). A first clad layer (3), a first clad layer (3), and a second clad layer (7) of the second conductivity type laminated on the second optical waveguide layer (6).
Of the optical waveguide layer (4), the active layer (5), the second optical waveguide layer (6) and the second cladding layer (7) of Zn _1-xy Cd
_{x Mg y S a Te b Se} 1-ab ( However, 0 ≦ x <1,
0 ≦ y <1, 0 ≦ a <1, 0 ≦ b <1) based compound semiconductor, the active layer (5) has two quantum well layers (5a, 5c), and two quantum wells Layer (5a,
The total thickness of 5c) is characterized by being 2 to 20 nm.

The semiconductor laser according to the eighth invention of the present invention is the semiconductor laser according to the seventh invention of the present invention, wherein the first cladding layer (3) and the second cladding layer (7) are made of a ZnMgSSe-based compound semiconductor. Consists, first
The optical waveguide layer (4) and the second optical waveguide layer (6) of
The active layer (5) is made of a Se-based compound semiconductor or a ZnSe-based compound semiconductor, and the active layer (5) is a first quantum well layer (5a) and a first quantum well layer (5) made of a ZnCdSe-based compound semiconductor.
a) A barrier layer (5b) made of a ZnSe-based compound semiconductor laminated on the a) and a Zn layer laminated on the barrier layer (5b)
The second quantum well layer (5 composed of a CdSe-based compound semiconductor
It is characterized by comprising c).

A semiconductor laser according to a ninth invention of the present invention is the semiconductor laser according to the seventh invention of the present invention, wherein the compound semiconductor substrate (1) is a GaAs substrate,
The first cladding layer (3) is laminated on a GaAs substrate via a buffer layer (2) made of ZnSe, and the first cladding layer (3) and the second cladding layer (7) are 0 <p ≦.
0.2, 0 <q ≦ 0.3 Zn _1-p Mg _p S _q Se _1-q
The first optical waveguide layer (4) and the second optical waveguide layer (6) are made of ZnS _u Se _1-u or Zn with 0 <u ≦ 0.1.
The active layer (5) is made of Se and has Zn of 0 <z ≦ 0.3.
_{A first} quantum well layer (5a) made of _1-z Cd _z Se, a barrier layer (5b) made of ZnSe laminated on the first quantum well layer (5a) and a barrier layer (5b) laminated A second quantum well layer (5c) made of Zn _1-z Cd _z Se with 0 <z ≦ 0.3, the first clad layer (3) and the second clad layer (7) and the first clad layer (3). Quantum well layer (5
The bandgap difference between a) and the second quantum well layer (5c) is 0.25 eV or more, and the first optical waveguide layer (4) and the second optical waveguide layer (6) are The difference in band gap between the quantum well layer (5a) and the second quantum well layer (5c) is 0.1 eV or more.

The semiconductor laser according to the tenth aspect of the present invention is the semiconductor laser according to the seventh aspect of the present invention, wherein the first cladding layer (3) and the second cladding layer (7) are made of ZnMgSSe type compound semiconductor. And the first optical waveguide layer (4) and the second optical waveguide layer (6) are Zn
The active layer (5) is made of a MgSSe-based compound semiconductor and is made of Z
A first quantum well layer (5a) made of an nSe-based compound semiconductor or a ZnSSe-based compound semiconductor, a barrier layer (5b) and a barrier layer (5b) made of a ZnMgSSe-based compound semiconductor laminated on the first quantum well layer (5a). 5b) is a second quantum well layer (5c) made of a ZnSe-based compound semiconductor or a ZnSSe-based compound semiconductor, which is laminated on top of the second quantum well layer (5c).

The semiconductor laser according to the eleventh invention of the present invention is the semiconductor laser according to the seventh invention of the present invention, wherein the compound semiconductor substrate (1) is a GaAs substrate and the first cladding layer (3) is made of ZnSe. The first cladding layer (3) and the second cladding layer (7) are laminated on the GaAs substrate with the buffer layer (2) made of 0.1.
Zn _1-p M with 1 ≦ p ≦ 0.4 and 0.15 ≦ q ≦ 0.45
g _p S _q Se _1-q , and the first optical waveguide layer (4) and the second optical waveguide layer (6) are 0.05 ≦ p ≦ 0.15,
The first quantum well layer (5a) and the first quantum well layer (5a) are made of Zn _1-p Mg _p S _q Se _{1-q with} 0.1 ≦ q ≦ 0.2 and the active layer (5) is made of ZnSe. Zn of 0.05 ≦ p ≦ 0.15 and 0.1 ≦ q ≦ 0.2 stacked on (5a)
_A barrier layer (5b) made of _1-p Mg _p S _q Se _1-q and a second quantum well layer (5c) made of ZnSe laminated on the barrier layer (5b), and the first cladding layer (5c). 3)
And the second cladding layer (7) and the first quantum well layer (5
The bandgap difference between a) and the second quantum well layer (5c) is 0.25 eV or more, and the first optical waveguide layer (4) and the second optical waveguide layer (6) are The difference in band gap between the quantum well layer (5a) and the second quantum well layer (5c) is 0.1 eV or more.

The semiconductor laser according to the twelfth invention of the present invention is the semiconductor laser according to the seventh invention of the present invention, wherein the compound semiconductor substrate (1) is a GaAs substrate and the first cladding layer (3) is made of ZnSe. The first cladding layer (3) and the second cladding layer (7) are laminated on the GaAs substrate with the buffer layer (2) made of 0.1.
Zn _1-p M with 15 ≦ p ≦ 0.5 and 0.2 ≦ q ≦ 0.55
g _p S _q Se _1-q , and the first optical waveguide layer (4) and the second optical waveguide layer (6) are 0.1 ≦ p ≦ 0.2, 0.1.
5 ≦ q ≦ 0.25 of Zn _1-p Mg _p S _q Se _1-q , and the active layer (5) is 0.01 ≦ u ≦ 0.1 of ZnS _u S
a _first quantum well layer (5a) made of e ₁ -u, 0.1 ≦ p ≦ 0.2 stacked on the first quantum well layer (5a),
0.15 ≦ q ≦ 0.25, Zn _1-p Mg _p S _q Se _1-q
A _first quantum well layer (5c) made of ZnS _u Se _{1-u with} 0.01 ≦ u ≦ 0.1 laminated on the barrier layer (5b). The difference in bandgap between the clad layer (3) and the second clad layer (7) and the first quantum well layer (5a) and the second quantum well layer (5c) is 0.25 eV or more. , The bandgap difference between the first optical waveguide layer (4) and the second optical waveguide layer (6) and the first quantum well layer (5a) and the second quantum well layer (5c) is 0. It is characterized in that it is 0.1 eV or more.

A semiconductor laser according to a thirteenth invention of the present invention comprises a first clad layer (3) of the first conductivity type laminated on a compound semiconductor substrate (1) and a first clad layer (3). An active layer (5) stacked on the active layer (5) and a second clad layer (7) of the second conductivity type stacked on the active layer (5). The first clad layer (3) and the active layer (5) and the second cladding layer (7) are Zn _1-xy Cd _x Mg _y S _a T
e _b Se _1-ab (where 0 ≦ x <1, 0 ≦ y <1, 0
≦ a <1, 0 ≦ b <1) based compound semiconductor, and the active layer (5) has a thickness of 15 to 60 nm.

The semiconductor laser according to the fourteenth invention of the present invention is the semiconductor laser according to the thirteenth invention of the present invention, wherein the first cladding layer (3) and the second cladding layer (7) are made of ZnMgSSe compound semiconductor. Consists of
The active layer (5) is characterized by being made of a ZnSSe-based compound semiconductor, a ZnSe-based compound semiconductor or a ZnCdSe-based compound semiconductor.

The semiconductor laser according to the fifteenth aspect of the present invention is the semiconductor laser according to the thirteenth aspect of the present invention, wherein the compound semiconductor substrate (1) is a GaAs substrate and the first cladding layer (3) is made of ZnSe. The first cladding layer (3) and the second cladding layer (7) are laminated on the GaAs substrate with the buffer layer (2) made of 0.1.
Zn _1-p M with 1 ≦ p ≦ 0.4 and 0.15 ≦ q ≦ 0.45
g _p S _q Se _1-q , the active layer (5) is ZnSe, and the band gap between the first cladding layer (3) and the second cladding layer (7) and the active layer (5) Is characterized by being 0.25 eV or more.

The semiconductor laser according to the 16th aspect of the present invention is the semiconductor laser according to the 13th aspect of the present invention, wherein the compound semiconductor substrate (1) is a GaAs substrate and the first cladding layer (3) is made of ZnSe. The first cladding layer (3) and the second cladding layer (7) are laminated on the GaAs substrate with the buffer layer (2) made of 0.1.
Zn _1-p M with 15 ≦ p ≦ 0.5 and 0.2 ≦ q ≦ 0.55
g _p S _q Se _1-q , and the active layer (5) has 0 <u ≦
Consist 0.1 of ZnS _u Se _1-u, the difference in band gap between the first cladding layer (3) and a second cladding layer (7) active layer (5) in the above 0.25eV It is characterized by being.

The semiconductor laser according to the 17th aspect of the present invention is the semiconductor laser according to the 13th aspect of the present invention, wherein the compound semiconductor substrate (1) is a GaAs substrate and the first cladding layer (3) is made of ZnSe. The first cladding layer (3) and the second cladding layer (7) are laminated on the GaAs substrate with the buffer layer (2) consisting of
Zn _1-p Mg _p S _q Se with _p ≦ 0.2 and 0 <q ≦ 0.3
_1-q , the active layer (5) is Zn with 0 <z ≦ 0.3
_1-z Cd _z Se, characterized in that the band gap difference between the first cladding layer (3) and the second cladding layer (7) and the active layer (5) is 0.25 eV or more. It is what

The semiconductor laser according to the eighteenth invention of the present invention is the first clad layer (3) of the first conductivity type laminated on the compound semiconductor substrate (1) and the first clad layer (3). An active layer (5) stacked on the active layer (5) and a second clad layer (7) of the second conductivity type stacked on the active layer (5). The first clad layer (3) and the active layer (5) and the second cladding layer (7) are Zn _1-xy Cd _x Mg _y S _a T
e _b Se _1-ab (where 0 ≦ x <1, 0 ≦ y <1, 0
≦ a <1, 0 ≦ b <1) based compound semiconductor, the active layer (5) has a plurality of quantum well layers, and the total thickness of the plurality of quantum well layers is 10 to 35 nm. It is characterized by that.

The semiconductor laser according to the nineteenth invention of the present invention is the semiconductor laser according to the eighteenth invention of the present invention, wherein the first cladding layer (3) and the second cladding layer (7) are made of ZnMgSSe compound semiconductor. Consists of
The active layer (5) is characterized by comprising a plurality of barrier layers made of ZnSSe-based compound semiconductor or ZnMgSSe-based compound semiconductor and a plurality of quantum well layers made of ZnSe-based compound semiconductor, which are alternately stacked.

The semiconductor laser according to the twentieth invention of the present invention is the semiconductor laser according to the eighteenth invention of the present invention, wherein the compound semiconductor substrate (1) is a GaAs substrate and the first cladding layer (3) is made of ZnSe. The first cladding layer (3) and the second cladding layer (7) are laminated on the GaAs substrate with the buffer layer (2) made of 0.1.
Zn _1-p M with 1 ≦ p ≦ 0.4 and 0.15 ≦ q ≦ 0.45
g _p S _q Se _1-q , and the active layer (5) is alternately laminated with 0.05 ≦ p ≦ 0.4 and 0.1 ≦ q ≦ 0.45 Zn _1-p Mg _p S _q. A plurality of barrier layers made of Se _1-q and a plurality of quantum well layers made of ZnSe, and a band gap between the first cladding layer (3) and the second cladding layer (7) and the quantum well layer. The difference is 0.25 eV or more, and the band gap difference between the barrier layer and the quantum well layer is 0.1 eV or more.

The semiconductor laser according to the twenty-first invention of the present invention is the semiconductor laser according to the eighteenth invention of the present invention, wherein the compound semiconductor substrate (1) is a GaAs substrate and the first cladding layer (3) is made of ZnSe. The first cladding layer (3) and the second cladding layer (7) are laminated on the GaAs substrate with the buffer layer (2) made of 0.1.
Zn _1-p M with 15 ≦ p ≦ 0.5 and 0.2 ≦ q ≦ 0.55
g _p S _q Se _1-q , and the active layers (5) are alternately laminated with 0.1 ≦ p ≦ 0.5, 0.15 ≦ q ≦ 0.55 Zn _1-p Mg _p S _q A plurality of barrier layers made of Se _1-q and a plurality of quantum well layers made of ZnS _u Se _{1-u with} 0 <u ≦ 0.1, and a first cladding layer (3) and a second cladding layer.
The band gap difference between the cladding layer (7) and the quantum well layer is 0.25 eV or more, and the band gap difference between the barrier layer and the quantum well layer is 0.1 eV or more. It is what

[0032]

According to the semiconductor laser of the first invention, the first clad layer (3) and the second clad layer (7) are made of a Zn _1-xy Cd _x Mg _y S _a Te _b Se _1-ab compound. In semiconductor, x = 0 and b = 0, that is, Z
By forming an nMgSSe-based compound semiconductor, Z
A semiconductor laser having an SCH structure capable of emitting blue or green light can be realized by using an nMgSSe compound semiconductor as a material for the cladding layer. Moreover,
Since the active layer (5) has a single quantum well layer (5b) and the thickness of the quantum well layer (5b) is 2 to 20 nm, this semiconductor laser has a low threshold current.

According to the semiconductor lasers of the second invention to the sixth invention, a semiconductor which uses ZnMgSSe type compound semiconductor as a material of the cladding layer and has a SCH structure capable of emitting green light and having a low threshold current. A laser can be realized.

According to the semiconductor laser according to the seventh invention, the first cladding layer (3) and a second cladding layer _{(7) Zn 1-xy Cd} x Mg y S a Te b Se 1-ab
A compound semiconductor having x = 0 and b = 0, that is, a ZnMgSSe compound semiconductor is used as a material for the clad layer and is capable of emitting blue or green S by using a ZnMgSSe compound semiconductor.
A semiconductor laser having a CH structure can be realized. Moreover, the active layer (5) is composed of two quantum well layers (5b,
5d) and the total thickness of the two quantum well layers (5b, 5d) being 2-20 nm, this semiconductor laser has a low threshold current.

According to the semiconductor lasers of the eighth invention to the twelfth invention, a semiconductor which uses ZnMgSSe compound semiconductor as a material for the cladding layer and which can emit green light and has a low threshold current SCH structure. A laser can be realized.

According to the semiconductor laser of the thirteenth invention, the first cladding layer (3) and the second cladding layer (7) are made of Zn _1-xy Cd _x Mg _y S _a Te _b Se _1-ab.
Of a compound semiconductor having x = 0 and b = 0, that is, a ZnMgSSe compound semiconductor is used to form a clad layer, and a DH structure capable of emitting light in a greenish blue color. It is possible to realize a semiconductor laser having Moreover, since the thickness of the active layer (5) is 15 to 60 nm, this semiconductor laser has a low threshold current.

According to the semiconductor lasers of the fourteenth invention to the seventeenth invention, a DH structure which uses ZnMgSSe compound semiconductor as a material for the cladding layer and which can emit light in blue or green and has a low threshold current is provided. A semiconductor laser having the same can be realized.

According to the semiconductor laser of the eighteenth invention, the first clad layer (3) and the second clad layer (7) are made of Zn _1-xy Cd _x Mg _y S _a Te _b Se _1-ab.
A compound-based compound semiconductor having x = 0 and b = 0, that is, a DH structure capable of emitting light in blue or green by using a ZnMgSSe-based compound semiconductor as a material for a cladding layer by forming a ZnMgSSe-based compound semiconductor. A semiconductor laser having the same can be realized. Moreover, since the active layer (5) has a plurality of quantum well layers and the total thickness of the plurality of quantum well layers is 10 to 35 nm, this semiconductor laser has a low threshold current.

According to the semiconductor lasers of the nineteenth invention to the twenty-first invention, a DH structure which uses ZnMgSSe compound semiconductor as a material of the cladding layer and is capable of emitting blue or green light and having a low threshold current is used. A semiconductor laser having the same can be realized.

[0040]

Embodiments of the present invention will be described below with reference to the drawings. In all the drawings of the embodiments, the same or corresponding parts are designated by the same reference numerals.

FIG. 1 shows a semiconductor laser according to the first embodiment of the present invention. The semiconductor laser according to the first embodiment has an SCH structure.

As shown in FIG. 1, in the semiconductor laser according to the first embodiment, for example, S is used as an n-type impurity.
On the n-type GaAs substrate 1 having a (100) plane orientation doped with i, for example, n doped with Cl as an n-type impurity
Type ZnSe buffer layer 2, for example, Cl as an n-type impurity
N-type Zn _1-p Mg _p S _q Se _1-q cladding layer 3 doped with, for example, n doped with Cl as an n-type impurity
-Type ZnSe optical waveguide layer 4, active layer 5, for example p-type ZnSe optical waveguide layer 6 doped with N as a p-type impurity, for example p _- type Zn _1-p Mg _p doped with N as a p-type impurity
An S _q Se _1-q cladding layer 7 and a p-type ZnSe cap layer 8 doped with N as a p-type impurity, for example, are sequentially stacked.

Further, on the p-type ZnSe cap layer 8, an insulating layer 9 made of, for example, polyimide, SiO _x film, SiN _x film or the like having a stripe-shaped opening 9a is formed. Then, through this opening 9a, p-type Zn
A p-side electrode 10 such as an Au / Pd electrode or an Au electrode is in contact with the Se cap layer 8. On the other hand, on the back surface of the n-type GaAs substrate 1, for example, an n-type
The side electrode 11 is in contact.

In the first embodiment, the active layer 5 has a single quantum well structure composed of an i-type Zn _{1 -z} Cd _z Se quantum well layer having a thickness of 6 nm, for example. In this case, n-type Z
The nSe optical waveguide layer 4 and the p-type ZnSe optical waveguide layer 6 form a barrier layer.

The Mg composition ratio p of the n-type Zn _1-p Mg _p S _q Se _1-q cladding layer 3 and the p-type Zn _1-p Mg _p S _q Se _1-q cladding layer 7 is 0.07, for example. The S composition ratio q is, for example, 0.14, and the band gap E _{g at} that time is
Is about 2.87 eV. The Mg composition ratio p = 0.
07 and n-type Zn _1-p with S composition ratio q = 0.14
Mg _p S _q Se _1-q cladding layer 3 and p-type Zn _1-p M
The g _p S _q Se _1-q cladding layer 7 is lattice-matched with GaAs. In addition, the n-type ZnSe optical waveguide layer 4 and the p-type ZnSe
The bandgap E _g of the optical waveguide layer 6 is about 2.72 eV. Further, i-type Zn _1-z Cd _z S constituting the active layer 5 is formed.
The Cd composition ratio z of the e quantum well layer is, for example, 0.14,
The band gap E _{g at} that time is about 2.54 eV. In this case, the n-type Zn _1-p Mg _p S _q Se _1-q clad layer 3 and the p-type Zn _1-p Mg _p S _q Se _1-q clad layer 7 and the i-type Zn _1- constituting the active layer 5 are formed. The difference ΔE _g of the band gap E _{g from} the _z Cd _z Se quantum well layer is 0.3.
3 eV, n-type ZnSe optical waveguide layer 4 and p-type Zn
I-type Zn _1-z Cd forming the Se optical waveguide layer 6 and the active layer 5
the difference ΔE of the band gap E _g between the _z Se quantum well layer
_g is 0.18 eV. n-type Zn _1-p Mg _p S _q Se
_1-q cladding layer 3, n-type ZnSe optical waveguide layer 4, active layer 5, p-type ZnSe optical waveguide layer 6 and p-type Zn _1-p Mg _p
The energy band diagram of the S _q Se _1-q clad layer 7 is p =
It is shown in FIG. 2 together with the values of the bandgap E _g of these layers when 0.07, q = 0.14 and z = 0.14. In FIG. 2, E _c is energy at the lower end of the conduction band (the same applies hereinafter).

The thickness of each of the n-type Zn _1-p Mg _p S _q Se _1-q cladding layer 3 and the p-type Zn _1-p Mg _p S _q Se _1-q cladding layer 7 is preferably 0.5 μm or more. Was chosen as
Specifically, the thickness of the n-type Zn _1-p Mg _p S _q Se _1-q cladding layer 3 is, for example, 1 μm, and the p-type Zn _1-p Mg _p S _q Se
The thickness of the _1-q clad layer 7 is selected to be 0.6 μm, for example. In addition, the n-type ZnSe optical waveguide layer 4 and the p-type ZnSe
The thickness of the optical waveguide layer 6 is preferably 20 to 100 nm, respectively.
Is selected, and specifically, for example, each is selected to be 50 nm. Further, the thickness of the p-type ZnSe cap layer 8 is preferably selected to be 0.5 μm or more.

Since the n-type ZnSe buffer layer 2 has a slight lattice mismatch between ZnSe and GaAs, the n-type ZnSe buffer layer is caused by this lattice mismatch. In order to prevent dislocation from occurring during epitaxial growth of the layer 2 and each layer thereon, it is selected to be sufficiently smaller than the critical film thickness of ZnSe (up to 100 nm), specifically 2 nm, for example.

Next, a method of manufacturing the semiconductor laser according to the first embodiment constructed as described above will be described.

In order to manufacture the semiconductor laser according to the first embodiment, first, the n-type ZnSe buffer layer 2 and the n-type Zn _{1-p are formed} on the n-type GaAs substrate 1 by, for example, the molecular beam epitaxy (MBE) method. Mg _p S _q Se _1-q cladding layer 3, n-type ZnSe optical waveguide layer 4, i-type Zn _1-z Cd _z S
An active layer 5 composed of an e-quantum well layer, a p-type ZnSe optical waveguide layer 6, a p-type Zn _1-p Mg _{p Sq} Se _1-q cladding layer 7 and a p-type ZnSe cap layer 8 are sequentially epitaxially grown.

In the above epitaxial growth by the MBE method, for example, a Zn raw material has a purity of 99.99.
99% of Zn is used, and the purity of Mg is 99.9%.
Of Mg and 99.9999% Zn as the S raw material
S is used, and Se having a purity of 99.9999% is used as the Se raw material.
e is used. In addition, the n-type ZnSe buffer layer 2 and the n-type Z
n _1-p Mg _p S _q Se _1-q cladding layer 3 and n-type Zn
The doping of Cl as an n-type impurity in the Se optical waveguide layer 4 is performed by using ZnCl ₂ with a purity of 99.9999% as a dopant, and the p-type ZnSe optical waveguide layer 6 and the p-type Z optical waveguide layer 6, respectively.
n _1-p Mg _p S _q Se _1-q cladding layer 7 and p-type Zn
Doping of N as a p-type impurity in the Se cap layer 8 is performed by irradiating N ₂ plasma generated by electron cyclotron resonance (ECR), for example.

Next, after forming the insulating layer 9 on the entire surface of the p-type ZnSe cap layer 8, a predetermined portion of the insulating layer 9 is removed to form the opening 9a. Next, an Au / Pd film or an Au film is vacuum-deposited on the entire surface to form a p-side electrode 10 such as an Au / Pd electrode or an Au electrode, and then heat treatment is performed if necessary, so that the p-side electrode 10 is formed. The p-type ZnSe cap layer 8
Make ohmic contact with. On the other hand, an n-side electrode 11 such as an In electrode is formed on the back surface of the n-type GaAs substrate 1.

Thereafter, the n-type GaAs substrate 1 on which the laser structure is formed as described above is cleaved into, for example, a bar shape to form a resonator end face, and the bar is cleaved to form a chip for packaging. .

FIG. 3 shows the measurement results of the light output-current characteristics of the semiconductor laser according to the first embodiment. The thickness of the i-type Zn _1-z Cd _z Se quantum well layer constituting the active layer 5 of the single quantum well (SQW) structure of the semiconductor laser used for this measurement is 6 nm. For comparison, FIG. 3 shows, for comparison, a triple quantum well (TQW) in which an i-type Zn _1-z Cd _z Se quantum well layer having a thickness of 6 nm and an i-type ZnSe barrier layer having a thickness of 4 nm are alternately stacked. ) The measurement results of the optical output-current characteristics of the semiconductor laser having the same structure as the semiconductor laser according to the first embodiment except that the structure is also shown. In the latter case, the total thickness of the three quantum well layers in the active layer is 6 nm × 3 = 18 nm.

As is apparent from FIG. 3, the threshold current of the semiconductor laser according to the first embodiment when the thickness of the quantum well layer constituting the active layer 5 having the single quantum well structure is 6 nm is Compared with the threshold current of a semiconductor laser in which the total thickness of the three quantum well layers in the active layer of the triple quantum well structure is 18 nm, it is reduced to about 1/2.

When the oscillation wavelength of the semiconductor laser according to the first embodiment was measured, it was about 498 at room temperature.
was nm.

As described above, according to the first embodiment,
n-type Zn _1-p Mg _p S _q Se _1-q cladding layer 3, n-type Z
nSe optical waveguide layer 4, active layer 5 having a single quantum well structure, p-type ZnSe optical waveguide layer 6 and p-type Zn _1-p Mg _p S _q Se
By forming a laser structure with the _1-q clad layer 7 and selecting the thickness of the i-type Zn _1-z Cd _z Se quantum well layer constituting the active layer 5 to be as small as 6 nm, for example,
It is possible to realize a semiconductor laser using ZnMgSSe-based compound semiconductor as a material for the cladding layer and having a SCH structure that emits green light at room temperature and can oscillate at a wavelength of about 498 nm and has a low threshold current density. Further, since this semiconductor laser has a low threshold current density, heat generation can be suppressed, and life characteristics can be improved. Furthermore, this semiconductor laser has a low threshold current and thus consumes low power.

Next explained is a semiconductor laser according to the second embodiment of the invention.

The semiconductor laser according to the second embodiment is
The active layer 5 has a structure similar to that of the semiconductor laser according to the first embodiment except that the active layer 5 has a double quantum well structure as shown in FIG. As shown in FIG. 4, in the semiconductor laser according to the second embodiment, the active layer 5 is made of i-type Zn.
_1-z Cd _z Se quantum well layer 5a, i-type ZnSe barrier layer 5
It has a double quantum well structure in which b and i-type Zn _1-z Cd _z Se quantum well layers 5 c are sequentially stacked. Where i type Z
n _1-z Cd _z Se quantum well layer 5 a and i-type Zn _1-z C
The thickness of each of the d _z Se quantum well layers 5c is, for example, 6 nm.
And the thickness of the i-type ZnSe barrier layer 5b is 4 nm, for example.
Is. In this case, two i-type Zn in the active layer 5
_1-z Cd _z Se quantum well layer 5a and i-type Zn _1-z Cd
The total thickness of the _z Se quantum well layer 5c is 6 nm × 2 = 12.
nm. An energy band diagram of this active layer 5 is shown in FIG.
Shown in.

The method of manufacturing the semiconductor laser according to the second embodiment is the same as the method of manufacturing the semiconductor laser according to the first embodiment, and the description thereof will be omitted.

According to the second embodiment as well, similar to the semiconductor laser according to the first embodiment, ZnMgSSe compound semiconductor is used as the material for the cladding layer, which can emit green light at room temperature and has a low threshold current density. A semiconductor laser having an SCH structure can be realized.

Next explained is a semiconductor laser according to the third embodiment of the invention.

FIG. 6 shows a semiconductor laser according to the third embodiment. The semiconductor laser according to the third embodiment is DH
It has a structure.

As shown in FIG. 6, in the semiconductor laser according to the third embodiment, for example, S is used as an n-type impurity.
On the n-type GaAs substrate 1 having a (100) plane orientation doped with i, for example, n doped with Cl as an n-type impurity
Type ZnSe buffer layer 2, for example, Cl as an n-type impurity
N-type Zn _1-p Mg _p S _q Se _1-q clad layer 3, active layer 5, for example, p-type Zn _1-p Mg _p S _q Se _1-q doped with N as a p-type impurity Cladding layer 7 and p-type Zn doped with N as a p-type impurity, for example
The Se cap layer 8 is sequentially stacked.

An insulating layer 9 is formed on the p-type ZnSe cap layer 8, and the p-side electrode 1 is formed on the p-type ZnSe cap layer 8 through the stripe-shaped openings 9a formed in the insulating layer 9.
The fact that 0 is in contact and the n-side electrode 11 is in contact with the back surface of the n-type GaAs substrate 1 is the same as in the semiconductor laser according to the first embodiment.

In this case, the active layer 5 is a single layer of ZnSe.
Layer, a ZnS _u Se _1-u layer, or a Zn _1-z Cd _z Se layer. The thickness of the active layer 5 is 15 to 6
It is selected in the range of 0 nm, preferably 20 to 40 nm.

When the active layer 5 is formed of a ZnSe layer, the n-type Zn _1-p Mg _p S _q Se _1-q clad layer 3 and the p-type Zn _1-p Mg _p S _q Se _1-q clad layer 7 are formed. Mg
The composition ratio p is, for example, 0.23, and the S composition ratio q is, for example, 0.28. The bandgap E _g of the active layer 5 at this time is about 2.72 eV, and n-type Zn _1-p Mg _p S _q Se
_1-q clad layer 3 and p-type Zn _1-p Mg _p S _q Se
The band gap E _g of the _1-q cladding layer 7 is about 3.05e.
V. In this case, n-type Zn _1-p Mg _p S _q Se _1-q
The difference ΔE _g of the band gap E _g between the clad layer 3 and the p-type Zn _1-p Mg _p S _q Se _1-q clad layer 7 and the active layer 5 is 0.33 eV.

Further, the active layer 5 is formed of ZnS _u with u = 0.06.
When it is formed of a Se _1-u layer, n-type Zn _1-p Mg _p S
_q Se _1-q clad layer 3 and p-type Zn _1-p Mg _p S _q
The Mg composition ratio p of the Se _1-q cladding layer 7 is, for example, 0.2.
6, and the S composition ratio q is, for example, 0.31. At this time, the band gap E _g of the active layer 5 is about 2.76 eV, n
The band gap E _g of the type Zn _1-p Mg _p S _q Se _1-q cladding layer 3 and the p-type Zn _1-p Mg _p S _q Se _1-q cladding layer 7 is about 3.10 eV. In this case, n-type Zn
_1-p Mg _p S _q Se _1-q cladding layer 3 and p-type Zn
The difference ΔE _g of the band gap E _g between the _1-p Mg _p S _q Se _1-q cladding layer 7 and the active layer 5 is 0.34 eV.

Further, the active layer 5 is formed of Zn = 0.14.
_When formed by a _1-z Cd _z Se layer, n-type Zn _1-p M
g _p S _q Se _1-q cladding layer 3 and p-type Zn _1-p Mg
The Mg composition ratio p of the _p S _q Se _1-q cladding layer 7 is, for example, 0.07, and the S composition ratio q is, for example, 0.14. At this time, the band gap E _g of the active layer 5 is about 2.54e.
The band gap E _g of V, the n-type Zn _1-p Mg _p S _q Se _1-q cladding layer 3 and the p-type Zn _1-p Mg _p S _q Se _1-q cladding layer 7 is about 2.87 eV. In this case n
The difference ΔE _{g in the} bandgap E _g between the active ZnO _1-p Mg _p S _q Se _1-q clad layer 3 and the p-type Zn _1-p Mg _p S _q Se _1-q clad layer 7 and the active layer 5. Is 0.33 eV.

N-type ZnSe buffer layer 2, n-type Zn _1-p
Mg _p S _q Se _1-q clad layer 3, active layer 5, p-type Zn
_1-p Mg _p S _q Se _1-q clad layer 7 and p-type ZnS
The thickness of the e-cap layer 8 can be selected to the same value as that of the semiconductor laser according to the first embodiment.

The method of manufacturing the semiconductor laser according to the third embodiment is the same as the method of manufacturing the semiconductor laser according to the first embodiment, and the description thereof will be omitted.

According to this third embodiment, a single layer of ZnSe
Layer, ZnS _u Se _1-u layer or Zn _1-z Cd _z Se layer, the active layer 5 is selected to have a sufficiently small thickness of 15 to 60 nm. Similarly, it is possible to realize a semiconductor laser having a low threshold current density DH structure capable of emitting blue or green light at room temperature using ZnMgSSe compound semiconductor as a material for the cladding layer.

Next explained is a semiconductor laser according to the fourth embodiment of the invention.

In the semiconductor laser according to the fourth embodiment, the active layer 5 has a plurality of barrier layers made of Zn _1-s Mg _{s St} Se _1-t and a plurality of quantum layers made of ZnSe or ZnS _u Se _1-u. It has the same structure as the semiconductor laser according to the third embodiment except that it has a multiple quantum well (MQW) structure in which well layers are alternately stacked. In this case, the total thickness of the quantum well layers in the active layer 5 is 1
It is selected in the range of 0 to 35 nm.

The barrier layer in the active layer 5 is made of Zn _1-s Mg _s
S _t Se is formed by _1-t, when forming the ZnSe quantum well layer, forming a barrier layer Zn _1-s Mg s _{S t}
The Mg composition ratio s and the S composition ratio t of Se ₁ -t are selected to be 0.1 and 0.16, respectively, or are selected to be 0.23 and 0.28, respectively. Further, in this case, the Mg composition ratio p and the S composition ratio q of the n-type Zn _1-p Mg _p S _q Se _1-q clad layer 3 and the p-type Zn _1-p Mg _p S _q Se _1-q clad layer 7 are Are selected to be 0.23 and 0.28, respectively. Z in the active layer 5 at this time
The bandgap E _g of the nSe quantum well layer is about 2.72e.
The band gap E _g of V, the n-type Zn _1-p Mg _p S _q Se _1-q cladding layer 3 and the p-type Zn _1-p Mg _p S _q Se _1-q cladding layer 7 is about 3.05 eV. In this case n
Type _{Zn 1-p Mg p S q} Se 1-q cladding layer 3 and the p-type _{Zn 1-p Mg p S q} Se 1-q cladding layer 7 and the band gap E between the ZnSe quantum well layer in the active layer 5 _g
Difference ΔE _g is 0.33 eV.

The barrier layer in the active layer 5 is made of Zn _1-s.
It is formed of Mg _{s St} Se _1-t , and the quantum well layer is ZnS.
Zn formed as a barrier layer when formed by _u Se _1-u
The Mg composition ratio s and the S composition ratio t of _1-s Mg _{s St} Se _1-t are selected to be 0.13 and 0.19, respectively, or are selected to be 0.26 and 0.31, respectively. Further, in this case, n-type Zn _1-p Mg _p S _q Se _1-q
The Mg composition ratio p and the S composition ratio q of the clad layer 3 and the p-type Zn _1-p Mg _p S _q Se _1-q clad layer 7 are selected to be 0.26 and 0.31, respectively. At this time, the band gap E _g of the ZnS _t Se _1-t quantum well layer in the active layer 5 is about 2.76 eV, and the n-type Zn _1-p Mg _p S
_q Se _1-q clad layer 3 and p-type Zn _1-p Mg _p S _q
The band gap E _g of the Se _1-q clad layer 7 is about 3.1.
It is 0 eV. In this case, n-type Zn _1-p Mg _p S _q Se
_1-q clad layer 3 and p-type Zn _1-p Mg _p S _q Se
ZnS _t Se _1-t in _1-q clad layer 7 and active layer 5
The difference ΔE _g of the band gap E _{g from} the quantum well layer is 0.34 eV.

The method of manufacturing the semiconductor laser according to the fourth embodiment is the same as the method of manufacturing the semiconductor laser according to the first embodiment, and the description thereof will be omitted.

According to the fourth embodiment as well, similar to the semiconductor laser according to the first embodiment, a low threshold current capable of emitting blue or green light at room temperature using ZnMgSSe compound semiconductor as a material for the cladding layer. Density D
A semiconductor laser having an H structure can be realized.

Next explained is a semiconductor laser according to the fifth embodiment of the invention.

As shown in FIG. 7, in the semiconductor laser according to the fifth embodiment, for example, S is used as an n-type impurity.
On the n-type GaAs substrate 1 having a (100) plane orientation doped with i, for example, n doped with Cl as an n-type impurity
Type ZnSe buffer layer 2, for example, Cl as an n-type impurity
N-type Zn _1-p Mg _p S _q Se _1-q cladding layer 3 doped with, for example, n doped with Cl as an n-type impurity
-Type ZnSe optical waveguide layer 4, active layer 5, for example p-type ZnSe optical waveguide layer 6 doped with N as a p-type impurity, for example p _- type Zn _1-p Mg _p doped with N as a p-type impurity
S _q Se _1-q cladding layer 7, for example N as p-type impurity
A p-type ZnS _v Se _1-v layer 12 doped with and a p-type ZnSe cap layer 8 doped with N as a p-type impurity, for example, are sequentially stacked. Here, p-type ZnS _v
The Se _1-v layer 12 is used as a layer for achieving lattice matching with the p-type Zn _1-p Mg _p S _q Se _1-q cladding layer 7 and is also used as an auxiliary p-type cladding layer.
In order to achieve lattice matching with the p-type Zn _1-p Mg _p S _q Se _1-q cladding layer 7, the S composition ratio v of the p-type ZnS _v Se _1-v layer 12 is preferably 0.06. To be elected.

In this case, the upper layers of the p-type ZnSe cap layer 8 and the p-type ZnS _v Se _1-v layer 12 are patterned in a stripe shape. The width of this stripe portion is, for example, 5 μm.

Further, a thickness of, for example, 30 is formed on the p-type ZnS _v Se _1-v layer 12 in the portion other than the above-mentioned stripe portion.
An insulating layer 9 made of a 0 nm alumina (Al ₂ O ₃ ) film is formed. Then, stripe-shaped p-type ZnS
A p-side electrode 10 is formed on the e cap layer 8 and the insulating layer 9. A portion of the p-side electrode 10 in contact with the p-type ZnSe cap layer 8 serves as a current passage. Here, the p-side electrode 10 has, for example, a thickness of 10 n.
m Pd film, 100 nm thick Pt film, and 300 nm thick
An Au / Pt / Pd electrode in which an Au film having a thickness of 10 nm is sequentially stacked is used. On the other hand, an n-side electrode 11 such as an In electrode is in contact with the back surface of the n-type GaAs substrate 1.

In the semiconductor laser according to the fifth embodiment, so-called end face coating is applied. That is, FIG. 8 shows a section parallel to the cavity length direction of the semiconductor laser according to the fifth embodiment. As shown in FIG.
Of the pair of resonator end faces perpendicular to the cavity length direction, the front end face from which the laser light is extracted is coated with a multilayer film composed of an Al ₂ O ₃ film 13 having a thickness of 74 nm and a Si film 14 having a thickness of 31 nm. The 74 nm-thick Al ₂ O ₃ film 13 and the thickness of ₃ nm are formed on the end face on the rear side from which laser light is not extracted, of the pair of cavity end faces perpendicular to the cavity length direction.
A multilayer film in which two 1-nm Si films 14 are stacked is coated. Here, the thickness of the multilayer film composed of the Al ₂ O ₃ film 13 and the Si film 14 is selected so that the optical distance obtained by multiplying the refractive index thereof is equal to 1/4 of the oscillation wavelength of the laser light. ing. In this case, the reflectance of the front end face is 70%, and the reflectance of the rear end face is 95%.
%.

In the fifth embodiment, the active layer 5 has a single quantum well structure composed of an i-type Zn _1-z Cd _z Se quantum well layer having a thickness of 9 nm, for example. In this case, n-type Z
Similar to the first embodiment, the nSe optical waveguide layer 4 and the p-type ZnSe optical waveguide layer 6 form a barrier layer.

The Mg composition ratio p of the n-type Zn _1-p Mg _p S _q Se _1-q cladding layer 3 and the p-type Zn _1-p Mg _p S _q Se _1-q cladding layer 7 is, for example, 0.09. The S composition ratio q is, for example, 0.18, and the band gap E _{g at} that time is
Is about 2.94 eV at 77K. The n-type Zn _1-p Mg _p S _q Se _1-q cladding layer 3 and the p-type Z having the Mg composition ratio p = 0.09 and the S composition ratio q = 0.18.
The n _1-p Mg _p S _q Se _1-q cladding layer 7 is lattice-matched with GaAs. In addition, i-type Zn _1-z C constituting the active layer 5
The Cd composition ratio z of the d _z Se quantum well layer is, for example, 0.19, and the band gap E _{g at} that time is 77 K, which is about 2.
It is 54 eV. In this case, n-type Zn _1-p Mg _p S _q S
e _1-q clad layer 3 and p-type Zn _1-p Mg _p S _q Se
_I- type Zn _1-z C constituting the _1-q clad layer 7 and the active layer 5
The difference Δg in the band gap E _g between the d _z Se quantum well layer and Δ
E _g is 0.40 eV.

In this case, n-type Zn _1-p Mg _p S _q Se
_1-q thickness of the cladding layer 3 is 1.5μm example, an impurity concentration N _D -N _A (however, N _D is the donor concentration, N
_A is an acceptor concentration) and is, for example, 5 × 10 ¹⁷ cm ⁻³ . The thickness of the n-type ZnSe waveguide layer 4 is 80nm for example, an impurity concentration N _D -N _A, for example, 5 × 10 ¹⁷ cm
^-3 . The thickness of the p-type ZnSe waveguide layer 6 is 80nm for example, for example, an impurity concentration N _A -N _D 5
It is × 10 ¹⁷ cm ^-3 . p-type Zn _1-p Mg _p S _q Se
_1-q thickness of the cladding layer 7 is 0.8μm example, the impurity concentration is N _A -N _D, for example, 2 × 10 ¹⁷ cm ^-3. The thickness of the p-type ZnS _v Se _1-v layer 12 is 0.8, for example.
μm, and the impurity concentration is N _A -N _D , for example, 8 × 10
^{It is 17} cm ^-3 . The thickness of the p-type ZnSe cap layer 8 is, for example, 45 nm, the impurity concentration is N _A -N _D, for example, 8 × 10 ¹⁷ cm ^-3. The n-type ZnSe buffer layer 2 has a thickness of 33 nm, for example.

The resonator length L of the semiconductor laser according to the fifth embodiment is selected to be, for example, 640 μm, and the width in the direction perpendicular to the resonator length direction is selected to be, for example, 400 μm.

Next, a method of manufacturing the semiconductor laser according to the fifth embodiment having the above-mentioned structure will be described.

To manufacture the semiconductor laser according to the fifth embodiment, first, for example, M on the n-type GaAs substrate 1.
By the BE method, for example, at a growth temperature of 280 ° C., n-type ZnSe
Buffer layer 2, n-type Zn _1-p Mg _{p Sq} Se _1-q cladding layer 3, n-type ZnSe optical waveguide layer 4, i-type Zn _1-z Cd _z
An active layer 5 composed of a Se quantum well layer, a p-type ZnSe optical waveguide layer 6, a p-type Zn _1-p Mg _{p Sq} Se _1-q cladding layer 7,
The p-type ZnS _v Se _1-v layer 12 and the p-type ZnSe cap layer 8 are sequentially epitaxially grown.

In the epitaxial growth by the MBE method described above, as in the first embodiment, Zn with a purity of 99.9999% was used as the Zn raw material, Mg with a purity of 99.9% was used as the Mg raw material, and the S raw material was used. As 99.99
99% ZnS is used, and the purity of the Se raw material is 99.9.
999% Se is used. In addition, Cl as an n-type impurity of the n-type ZnSe buffer layer 2, the n-type Zn _1-p Mg _{p Sq} Se _1-q cladding layer 3, and the n-type ZnSe optical waveguide layer 4.
For example, the doping of ZnCl is 99.9999% ZnCl
₂ is used as a dopant. Similar to the first embodiment, the p-type ZnSe optical waveguide layer 6 and the p-type Zn _1-p Mg _p S _q
Se _1-q cladding layer 7 and p-type ZnSe cap layer 8
The doping of N as a p-type impurity is performed by irradiating N ₂ plasma generated by ECR.

Next, after forming a stripe-shaped resist pattern (not shown) having a predetermined width on the p-type ZnSe cap layer 8, the thickness of the p-type ZnS _v Se _1-v layer 12 is used as a mask. Etching is performed by a wet etching method in the middle of the vertical direction. By this, p
The upper layer portion of the type ZnSe cap layer 8 and the p-type ZnS _v Se _1-v layer 12 is patterned in a stripe shape.

Next, an Al ₂ O ₃ film was vacuum-deposited on the entire surface while leaving the resist pattern used for the above-mentioned etching, and then this resist pattern was formed on the A film.
It is removed together with the l ₂ O ₃ film (lift-off). As a result, p-type ZnS _v Se _{1-v in the} part other than the stripe part
The insulating layer 9 made of an Al ₂ O ₃ film is formed only on the layer 12.

Next, a Pd film, a Pt film, and an Au film are sequentially vacuum-deposited on the entire surface of the stripe-shaped p-type ZnSe cap layer 8 and the insulating layer 9 to form a p-side electrode 10 composed of an Au / Pt / Pd electrode. The p-side electrode 10 is then subjected to a heat treatment, if necessary, to form the p-type ZnSe cap layer 8
Make ohmic contact with. On the other hand, an n-side electrode 11 such as an In electrode is formed on the back surface of the n-type GaAs substrate 1.

After that, the n-type GaAs substrate 1 on which the laser structure is formed as described above is cleaved into, for example, a bar shape having a width of 640 μm to form both resonator end faces, and then the front side of the resonator is formed by vacuum deposition. Al ₂ O ₃ film 13 and Si on the end face
A multi-layered film including the film 14 is formed, and a multi-layered film in which the Al ₂ O ₃ film 13 and the Si film 14 are repeated two cycles is formed on the rear end surface. After the end face coating is applied in this manner, the bar is cleaved into a chip having a width of 400 μm for packaging.

FIG. 9 shows the results of measuring the optical output-current characteristics of the semiconductor laser according to the fifth embodiment at room temperature (296K) with and without injection current. The measurement was carried out by mounting the laser chip on a heat sink made of, for example, copper such that the p-side electrode 10 was on the lower side, that is, p-side down. As can be seen from FIG. 9, the threshold current I _th when the injection current is continuously flowed is about 45 mA, which corresponds to the threshold current density J _th of about 1.5 kA / cm ² . On the other hand, the threshold current I _th when the injection current is made to flow in a pulse is about 42 mA. Here, the measurement of the light output-current characteristics when the injection current was continuously flowed was performed by increasing the injection current from 0 to 100 mA at a speed of 500 mA / sec. On the other hand, when the injection current is pulsed, the optical output-current characteristics are measured with a pulse width of 2 μm of the injection current.
s, the repetition rate was 1 ms. As can be seen from FIG. 9, the slope efficiency S _d when the injection current is made to flow in a pulsed manner and when it is made to flow continuously is 0.34 W / A, respectively.
And 0.31 W / A. The applied voltage between the p-side electrode 10 and the n-side electrode 11 at the threshold of laser oscillation is about 17V.

FIG. 10 shows the measurement result of the emission spectrum when the semiconductor laser according to the fifth embodiment is oscillated at room temperature (296K). As can be seen from FIG. 10, stimulated emission is observed at the wavelengths of 521.6 nm and 523.5 nm in the pulsed operation and the continuous operation, respectively.

As can be seen from the above, according to the fifth embodiment, the SC which emits green light and has a low threshold current density capable of continuous oscillation at a wavelength of 523.5 nm at room temperature.
A semiconductor laser having an H structure can be realized.

Although the embodiments of the present invention have been specifically described above, the present invention is not limited to the above-mentioned embodiments, and various modifications can be made based on the technical idea of the present invention.

For example, instead of the n-type ZnSe optical waveguide layer 4 and the p-type ZnSe optical waveguide layer 6 used in the above-described first, second and fifth embodiments, an i-type ZnSe optical waveguide layer is used. May be used.

In the first embodiment described above, the active layer 5 is composed only of the i-type Zn _1-z Cd _z Se quantum well layer, but the active layer 5 may be formed as shown in FIG. , The i-type ZnSe barrier layer 5b, the i-type Zn
_{A 1-z} Cd _z Se quantum well layer 5a and an i-type ZnSe barrier layer 5d may be sequentially stacked to form a single quantum well structure.
Here, the i-type Zn _1-z Cd _z Se quantum well layer 5 a has a thickness of, for example, 6 nm, and the i-type ZnSe barrier layer 5 b and the i-type ZnSe barrier layer 5 d have a thickness of, for example, 4 nm.
Is.

Similarly, as shown in FIG. 12, the active layer 5 in the above-mentioned second embodiment may be formed of i-type Zn as the case may be.
Se barrier layer 5b, i-type Zn _1-z Cd _z Se quantum well layer 5
a, i-type ZnSe barrier layer 5d, i-type Zn _1-z Cd _z Se
A double quantum well structure may be formed by sequentially stacking the quantum well layer 5c and the i-type ZnSe barrier layer 5e. Where i type Z
n _1-z Cd _z Se quantum well layer 5 a and i-type Zn _1-z C
The thickness of each of the d _z Se quantum well layers 5c is, for example, 6 nm.
The thicknesses of the i-type ZnSe barrier layer 5b, the i-type ZnSe barrier layer 5d, and the i-type ZnSe barrier layer 5e are each 4 nm, for example.

Further, in the above-mentioned first to fifth embodiments, the p-type ZnSe is formed on the p-type ZnSe cap layer 8.
By forming a p-type ZnTe cap layer that can easily obtain a higher impurity concentration than the cap layer 8, the p-type ZnTe is formed.
The p-side electrode 10 may be brought into contact with the cap layer. Further, at the junction between the p-type ZnTe cap layer and the p-type ZnSe cap layer 8, p-type ZnSe is formed.
In the depletion layer formed on the cap layer 8 side, p-type ZnTe is formed.
A multiple quantum well (MQW) layer having a structure in which a quantum well layer made of p-type ZnSe and a barrier layer made of p-type ZnSe are alternately laminated, and the thickness of each quantum well layer of this MQW layer is set to p The energy may be selected so as to be almost equal to the energy at the top of the valence band of n-type ZnSe and p-type ZnTe, and holes may be conducted by resonant tunneling through these quantum levels. This makes it possible to improve the contact characteristics of the p-side electrode 10.

Further, in the above-mentioned first to fifth embodiments, the p-type ZnSe optical waveguide layer 6 and the p-type Zn _1-p Mg _{p are formed.}
S _q Se _1-q clad layer 7, p-type ZnS _v Se _1-v layer 1
The doping of N as a p-type impurity in the 2 and p-type ZnSe cap layer 8 is performed by irradiating N ₂ plasma generated by ECR. The N doping is excited by, for example, high-frequency plasma. N ₂
It may be performed by irradiating.

Further, in the above-described first to fifth embodiments, the GaAs substrate is used as the compound semiconductor substrate, but the compound semiconductor substrate is, for example, Ga.
A P substrate or the like may be used.

[0104]

As described above, according to the present invention, it is possible to realize a low threshold current semiconductor laser capable of emitting blue or green light using a ZnMgSSe compound semiconductor as a material for a cladding layer. You can

[Brief description of drawings]

FIG. 1 is a sectional view showing a semiconductor laser according to a first embodiment of the present invention.

FIG. 2 is an energy band diagram of the semiconductor laser according to the first embodiment of the present invention.

FIG. 3 is a graph showing an example of measurement results of light output-current characteristics of the semiconductor laser according to the first embodiment of the present invention.

FIG. 4 is a sectional view showing a detailed structure of an active layer in a semiconductor laser according to a second embodiment of the present invention.

FIG. 5 is an energy band diagram of an active layer of a semiconductor laser according to a second embodiment of the present invention.

FIG. 6 is a sectional view showing a semiconductor laser according to a third embodiment of the present invention.

FIG. 7 is a sectional view showing a semiconductor laser according to a fifth embodiment of the present invention.

FIG. 8 is a sectional view showing a semiconductor laser according to a fifth embodiment of the present invention.

FIG. 9 is a graph showing an example of measurement results of optical output-current characteristics of a semiconductor laser according to a fifth embodiment of the present invention at room temperature.

FIG. 10 is a graph showing an example of the measurement result of the emission spectrum of the semiconductor laser according to the fifth embodiment of the present invention at room temperature.

FIG. 11 is a sectional view for explaining a modification of the first embodiment of the present invention.

FIG. 12 is a sectional view for explaining a modification of the second embodiment of the present invention.

FIG. 13: Semiconductor laser and SC having DH structure
6 is a graph showing the results of calculation of the dependence of the threshold current density of a semiconductor laser having an H structure on the thickness of the active layer.

FIG. 14 is a graph showing a decay curve of photoluminescence intensity from a ZnSSe active layer having a thickness of 70 nm in a semiconductor laser having a DH structure.

[Explanation of symbols]

1 n-type GaAs substrate 2 n-type ZnSe buffer layer 3 n-type Zn _1-p Mg _p S _q Se _1-q cladding layer 4 n-type ZnSe optical waveguide layer 5 active layer 6 p-type ZnSe optical waveguide layer 7 p-type Zn _{1 -p} Mg _p S _q Se _1-q clad layer 8 p-type ZnSe cap layer 9 insulating layer 9a opening 10 p-side electrode 11 n-side electrode 12 p-type ZnS _v Se _1-v layer 13 Al ₂ O ₃ film 14 Si film

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Noriichi Nakayama 6-735 Kita-Shinagawa, Shinagawa-ku, Tokyo Sony Corporation

Claims (21)

[Claims] 1. A first conductivity type first cladding layer laminated on a compound semiconductor substrate, a first optical waveguide layer laminated on the first cladding layer, and the first optical waveguide. An active layer laminated on the layer, a second optical waveguide layer laminated on the active layer, and a second conductivity type second cladding layer laminated on the second optical waveguide layer. a, the first cladding layer, said first optical waveguide layer, the active layer, the second optical waveguide layer and the second cladding layer is _{Zn 1-xy Cd x Mg y} S a Te b Se _1-ab (where 0 ≦ x <1, 0 ≦ y <1, 0 ≦ a <1, 0 ≦ b <
1) A semiconductor laser comprising a compound semiconductor, the active layer having a single quantum well layer, and the quantum well layer having a thickness of 2 to 20 nm. 2. The first clad layer and the second clad layer are made of ZnMgSSe-based compound semiconductor,
The first optical waveguide layer and the second optical waveguide layer are made of ZnS.
2. The semiconductor laser according to claim 1, wherein the semiconductor laser is made of Se-based compound semiconductor or ZnSe-based compound semiconductor, and the active layer is made of the quantum well layer made of ZnCdSe-based compound semiconductor. 3. The compound semiconductor substrate is a GaAs substrate, and the first cladding layer is laminated on the GaAs substrate with a buffer layer made of ZnSe interposed therebetween,
And the second cladding layer are 0 <p ≦
0.2, 0 <q ≦ 0.3 Zn _1-p Mg _p S _q Se _1-q
The first optical waveguide layer and the second optical waveguide layer are made of ZnS _u Se _1-u or ZnSe with 0 <u ≦ 0.1.
And the active layer is made of Zn _1-z Cd with 0 <z ≦ 0.3.
The quantum well layer is made of _z Se, and the band gap difference between the quantum well layer and the first cladding layer and the second cladding layer is 0.25 eV or more. The bandgap difference between the wave layer and the second optical waveguide layer and the quantum well layer is 0.1 eV.
The semiconductor laser according to claim 1, wherein the semiconductor laser is as described above. 4. The first clad layer and the second clad layer are made of ZnMgSSe compound semiconductor,
The first optical waveguide layer and the second optical waveguide layer are made of ZnM.
It is made of gSSe-based compound semiconductor, and the active layer is ZnS.
2. The quantum well layer made of an e-based compound semiconductor or a ZnSSe-based compound semiconductor.
The semiconductor laser described. 5. The compound semiconductor substrate is a GaAs substrate, and the first clad layer is laminated on the GaAs substrate via a buffer layer made of ZnSe.
And the second cladding layer is 0.1 ≦ p
Zn _1-p Mg _p S with ≦ 0.4, 0.15 ≦ q ≦ 0.45
_q Se _1-q , and the first optical waveguide layer and the second optical waveguide layer are 0.05 ≦ p ≦ 0.15 and 0.1 ≦ q ≦.
0.2 of Zn _1-p Mg _p S _q Se _1-q , the active layer comprises the quantum well layer of ZnSe, the first cladding layer and the second cladding layer and the quantum well. The bandgap difference between the quantum well layer and the first optical waveguide layer and the second optical waveguide layer is 0.25 eV or more, and the bandgap difference between the quantum well layer and the first optical waveguide layer is 0.
The semiconductor laser according to claim 1, which has a voltage of 1 eV or more. 6. The compound semiconductor substrate is a GaAs substrate, and the first clad layer is laminated on the GaAs substrate via a buffer layer made of ZnSe.
And the second cladding layer is 0.15 ≦
Zn _1-p Mg _p S with p ≦ 0.5 and 0.2 ≦ q ≦ 0.55
_q Se _1-q , and the first optical waveguide layer and the second optical waveguide layer are 0.1 ≦ p ≦ 0.2 and 0.15 ≦ q ≦.
0.25 Zn _1-p Mg _p S _q Se _1-q , and the active layer is the quantum well layer made of ZnS _u Se _{1-u with} 0.01 ≦ u ≦ 0.1. The bandgap difference between the first cladding layer and the second cladding layer and the quantum well layer is 0.25 eV or more.
2. The semiconductor laser according to claim 1, wherein a difference in bandgap between the quantum well layer and the second optical waveguide layer and the second optical waveguide layer is 0.1 eV or more. 7. A first conductivity type first cladding layer laminated on a compound semiconductor substrate, a first optical waveguide layer laminated on the first cladding layer, and the first optical waveguide. An active layer laminated on the layer, a second optical waveguide layer laminated on the active layer, and a second conductivity type second cladding layer laminated on the second optical waveguide layer. a, the first cladding layer, said first optical waveguide layer, the active layer, the second optical waveguide layer and the second cladding layer is _{Zn 1-xy Cd x Mg y} S a Te b Se _1-ab (where 0 ≦ x <1, 0 ≦ y <1, 0 ≦ a <1, 0 ≦ b <
1) A semiconductor laser comprising a compound semiconductor, the active layer having two quantum well layers, and the total thickness of the two quantum well layers being 2 to 20 nm. 8. The first cladding layer and the second cladding layer are made of ZnMgSSe-based compound semiconductor,
The first optical waveguide layer and the second optical waveguide layer are made of ZnS.
A Se-based compound semiconductor or a ZnSe-based compound semiconductor, wherein the active layer is a first quantum well layer made of a ZnCdSe-based compound semiconductor, a barrier layer made of a ZnSe-based compound semiconductor laminated on the first quantum well layer, and 8. The semiconductor laser according to claim 7, comprising a second quantum well layer made of a ZnCdSe compound semiconductor laminated on the barrier layer. 9. The compound semiconductor substrate is a GaAs substrate, and the first cladding layer is laminated on the GaAs substrate via a buffer layer made of ZnSe.
And the second cladding layer are 0 <p ≦
0.2, 0 <q ≦ 0.3 Zn _1-p Mg _p S _q Se _1-q
The first optical waveguide layer and the second optical waveguide layer are made of ZnS _u Se _1-u or ZnSe with 0 <u ≦ 0.1.
And the active layer is made of Zn _1-z Cd with 0 <z ≦ 0.3.
_a first quantum well layer made of _z Se, a barrier layer made of ZnSe stacked on the first quantum well layer, and a Zn _1-z Cd layer of 0 <z ≦ 0.3 stacked on the barrier layer _z S
a second quantum well layer made of e, and a band gap difference between the first cladding layer and the second cladding layer and the first quantum well layer and the second quantum well layer is 0.25 eV or more, and the bandgap difference between the first optical waveguide layer and the second optical waveguide layer and the first quantum well layer and the second quantum well layer is 0.1 eV. 8. The semiconductor laser according to claim 7, which is the above. 10. The first cladding layer and the second cladding layer
Clad layer of ZnMgSSe-based compound semiconductor, the first optical waveguide layer and the second optical waveguide layer are Z
It is made of nMgSSe-based compound semiconductor, and the active layer is Z
First quantum well layer made of nSe-based compound semiconductor or ZnSSe-based compound semiconductor, barrier layer made of ZnMgSSe-based compound semiconductor laminated on the first quantum well layer, and ZnSe-based compound laminated on the barrier layer 8. The semiconductor laser according to claim 7, comprising a second quantum well layer made of a semiconductor or ZnSSe-based compound semiconductor. 11. The compound semiconductor substrate is a GaAs substrate, the first cladding layer is laminated on the GaAs substrate via a buffer layer made of ZnSe, and the first cladding layer and the second cladding layer are stacked. Layer is 0.1 ≦
Zn _1-p Mg _{p with} p ≦ 0.4 and 0.15 ≦ q ≦ 0.45
S _q Se _1-q consists, said first optical waveguide layer and the second optical waveguide layer 0.05 ≦ p ≦ 0.15,0.1 ≦ q
≦ 0.2 of Zn _1-p Mg _p S _q Se _1-q , the active layer is a first quantum well layer of ZnSe,
0.05 ≦ p ≦ 0.15 stacked on the quantum well layer of
A barrier layer made of Zn _1-p Mg _p S _q Se _{1-q with} 0.1 ≦ q ≦ 0.2 and a second quantum well layer made of ZnSe stacked on the barrier layer; The bandgap difference between the first cladding layer and the second cladding layer and the first quantum well layer and the second quantum well layer is 0.25 eV or more, and the first optical waveguide layer and The bandgap difference between the second optical waveguide layer and the first quantum well layer and the second quantum well layer is 0.
The semiconductor laser according to claim 7, which has a voltage of 1 eV or more. 12. The compound semiconductor substrate is a GaAs substrate, the first cladding layer is laminated on the GaAs substrate via a buffer layer made of ZnSe, and the first cladding layer and the second cladding layer are stacked. Layer is 0.15
Zn _1-p Mg _{p with} ≦ p ≦ 0.5 and 0.2 ≦ q ≦ 0.55
It consists S _q Se _1-q, the first optical waveguide layer and the second optical waveguide layer 0.1 ≦ p ≦ 0.2,0.15 ≦ q ≦
0.25 Zn _1-p Mg _p S _q Se _1-q and the active layer is 0.01 ≦ u ≦ 0.1 ZnS _u Se _1-u . Barrier layer made of Zn _1-p Mg _p S _q Se _{1-q with} 0.1 ≦ p ≦ 0.2 and 0.15 ≦ q ≦ 0.25 laminated on the quantum well layer of No. ₁ and the above barrier layer ZnS _{u with} 0.01 ≦ u ≦ 0.1 stacked on top
A second quantum well layer made of Se _1-u,
The bandgap difference between the first cladding layer and the second cladding layer and the first quantum well layer and the second quantum well layer is 0.25 eV or more, and the first optical waveguide layer and 8. The bandgap difference between the second optical waveguide layer and the first quantum well layer and the second quantum well layer is 0.1 eV or more.
The semiconductor laser described. 13. A first laminated on a compound semiconductor substrate
A first clad layer of conductivity type; an active layer laminated on the first clad layer; and a second clad layer of second conductivity type laminated on the active layer; first cladding layer, said active layer and said second cladding layer is _{Zn 1-xy Cd x Mg y} S a Te b Se
_1-ab (where 0 ≦ x <1, 0 ≦ y <1, 0 ≦ a <
A semiconductor laser comprising a 1,0 ≦ b <1) -based compound semiconductor, wherein the active layer has a thickness of 15 to 60 nm. 14. The first cladding layer and the second cladding layer.
Clad layer of ZnMgSSe-based compound semiconductor, the active layer is ZnSSe-based compound semiconductor, ZnSe
14. The semiconductor laser according to claim 13, wherein the semiconductor laser is made of a compound semiconductor of the series or a compound semiconductor of the ZnCdSe series. 15. The compound semiconductor substrate is a GaAs substrate, the first cladding layer is laminated on the GaAs substrate via a buffer layer made of ZnSe, and the first cladding layer and the second cladding layer are stacked. Layer is 0.1 ≦
Zn _1-p Mg _{p with} p ≦ 0.4 and 0.15 ≦ q ≦ 0.45
_Sq Se _1-q , the active layer is made of ZnSe, and the band gap difference between the active layer and the first cladding layer and the second cladding layer is 0.25e.
14. The semiconductor laser according to claim 13, which is V or more. 16. The compound semiconductor substrate is a GaAs substrate, the first clad layer is laminated on the GaAs substrate via a buffer layer made of ZnSe, and the first clad layer and the second clad layer are stacked. Layer is 0.15
Zn _1-p Mg _{p with} ≦ p ≦ 0.5 and 0.2 ≦ q ≦ 0.55
_Sq Se _1-q , the active layer is ZnS _u Se _{1-u with} 0 <u ≦ 0.1, and is between the first cladding layer and the second cladding layer and the active layer. 14. The semiconductor laser according to claim 13, wherein the difference in bandgap between the two is 0.25 eV or more. 17. The compound semiconductor substrate is a GaAs substrate, the first clad layer is laminated on the GaAs substrate via a buffer layer made of ZnSe, and the first clad layer and the second clad layer are stacked. Layer is 0 <p ≦
0.2, 0 <q ≦ 0.3 Zn _1-p Mg _p S _q Se _1-q
And the active layer is made of Zn _1-z Cd with 0 <z ≦ 0.3.
_z Se, the first clad layer and the second clad layer
14. The difference in bandgap between the clad layer and the active layer of 0.25 eV or more.
The semiconductor laser described. 18. A first laminated on a compound semiconductor substrate
A first clad layer of conductivity type; an active layer laminated on the first clad layer; and a second clad layer of second conductivity type laminated on the active layer; first cladding layer, said active layer and said second cladding layer is _{Zn 1-xy Cd x Mg y} S a Te b Se
_1-ab (where 0 ≦ x <1, 0 ≦ y <1, 0 ≦ a <
1, 0 ≦ b <1) based compound semiconductor, the active layer has a plurality of quantum well layers, and the total thickness of the plurality of quantum well layers is 10 to 35 nm. Semiconductor lasers. 19. The first cladding layer and the second cladding layer.
Clad layer is made of ZnMgSSe-based compound semiconductor, and the active layer is made up of a plurality of barrier layers made of ZnSSe-based compound semiconductor or ZnMgSSe-based compound semiconductor and a plurality of quantum well layers made of ZnSe-based compound semiconductor. 19. The semiconductor laser according to claim 18, wherein: 20. The compound semiconductor substrate is a GaAs substrate, the first cladding layer is laminated on the GaAs substrate via a buffer layer made of ZnSe, and the first cladding layer and the second cladding layer. Layer is 0.1 ≦
Zn _1-p Mg _{p with} p ≦ 0.4 and 0.15 ≦ q ≦ 0.45
The active layer is made of S _q Se _{1 -q} , and the active layers are alternately stacked Zn of 0.05 ≦ p ≦ 0.4 and 0.1 ≦ q ≦ 0.45.
_1-p Mg _p S _q Se _1-q barrier layers and Z
The quantum well layer is composed of a plurality of quantum well layers made of nSe, and a bandgap difference between the quantum well layer and the first cladding layer and the second cladding layer is 0.25 eV or more. 19. The semiconductor laser according to claim 18, wherein a difference in band gap between the quantum well layer and the quantum well layer is 0.1 eV or more. 21. The compound semiconductor substrate is a GaAs substrate, the first cladding layer is laminated on the GaAs substrate via a buffer layer made of ZnSe, and the first cladding layer and the second cladding layer are stacked. Layer is 0.15
Zn _1-p Mg _{p with} ≦ p ≦ 0.5 and 0.2 ≦ q ≦ 0.55
The active layer is made of S _q Se _{1 -q} , and the active layers are alternately stacked Zn of 0.1 ≦ p ≦ 0.5 and 0.15 ≦ q ≦ 0.55.
_1-p Mg _p S _q Se _1-q barrier layers and 0
A plurality of quantum well layers made of ZnS _u Se _1-u satisfying <u ≦ 0.1, and a bandgap difference between the quantum well layers and the first cladding layer and the second cladding layer is 19. The semiconductor laser according to claim 18, wherein the semiconductor layer has a voltage difference of 0.25 eV or more and a bandgap difference between the barrier layer and the quantum well layer of 0.1 eV or more.