JPH07202340A - Visible-light semiconductor laser - Google Patents

Abstract

PURPOSE:To provide a high-output and long-life semiconductor laser which can be manufactured with improved reproducibility without generating defect such as transformation due to lattice mismatching and residual stress. CONSTITUTION:A double heterostructure part is constituted of an active layer 3 and clad layers 2 and 4 consisting of the II-Vl semiconductors and a ridge part 10 formed at the clad layers 4 directly above the active layer 3 is buried by a current block layer 5 formed by ZnSxTe1-x (0<X<=0.7). Since the energy gap of the current block layer 5 is small as compared with the energy gap of the active layer 3 to absorb light leaked to the clad layer 4 directly above the active layer 3. Also. the clad layers 2 and 4 match the lattice constant of Gaps substrate l and do not deteriorate easily and hence achieve a superb quality.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor laser having a loss-guide type double heterostructure part using a II-VI group compound semiconductor of the periodic table, and particularly to a fundamental transverse mode oscillation at a low threshold current. The present invention relates to a blue to blue-green semiconductor laser capable of oscillating.

[0002]

2. Description of the Related Art A semiconductor laser emitting blue or blue-green light has been produced in which a plurality of semiconductor layers made of a II-VI group compound of the periodic table are laminated to form a double hetero structure. As the semiconductor laser, for example, a semiconductor laser in which GaAs or ZnSe is used as the substrate material and ZnMgSSe or ZnSSe is used as the material of the clad layer having the double hetero structure is applicable.

When the cladding layer is formed of the above ZnMgSSe type material, a semiconductor laser in which an active layer is formed by using ZnCdSe which has a lattice match with the ZnMgSSe type material and has a smaller energy gap than the ZnMgSSe type material is used. Are known. (ELECTRONI
CS LETTERS, Vo129, No9, 766-
768 (1993)). On the other hand, when the cladding layer is formed of the ZnSSe-based material, ZnSSe or ZnCdSe having a smaller S composition than ZnSSe used for the cladding layer is used for the active layer in order to make the energy gap smaller than that of the cladding layer of the ZnSSe-based material. A semiconductor laser having a double hetero structure is known (Journal of the Institute of Electronics, Information and Communication Engineers, July 1993, p. 818).

In addition, InP is used for the substrate and ZnMg is used.
A semiconductor laser has been proposed in which CdSe is used for a cladding layer and an active layer to form a double hetero structure portion (Japanese Patent Laid-Open No. 5-21892).

However, in each of the above semiconductor lasers, current and light are not sufficiently confined in the horizontal direction of the active layer (direction along the surface of the substrate). On the other hand, it has been reported that the buried heterostructure used in the mixed crystal semiconductor laser using the III-V group material of the periodic table can be applied to the II-VI group semiconductor laser (1993). June Device Research
(Conference, Abstracts). Examples thereof are shown in FIGS. 8 and 9.

In the semiconductor laser shown in FIG. 8, a double hetero structure in which a ZnCdSe active layer 83 is sandwiched on both sides by an n-type cladding layer 82 made of n-type ZnMgSSe and a p-type ZnMgSSe cladding layer 84 on an n-type GaAs substrate 81. Parts are formed. The p-type cladding layer 84
Is formed in a mesa stripe shape, and its ridge portion 800
Are filled with a polycrystalline ZnS layer 85. A contact layer 86 and a Ti-Au layer 87 are formed on the ridge portion 800, a p-type electrode 89 is formed so as to cover the Ti-Au layer 87, and the n-type GaAs substrate 81 side is formed. An n-type electrode 88 is formed.

On the other hand, the semiconductor laser shown in FIG.
On the aAs substrate 91, a ZnSSe / ZnCdSe active layer 93 is formed on both sides of the n-type ZnMgSSe cladding layer 92 and p layer.
A double heterostructure portion sandwiched by the type ZnMgSSe cladding layer 94 is formed. The clad layer 94 is formed in a mesa stripe shape, and its ridge portion 900 is filled with a polyimide layer 95. In FIG. 9, 96 is p-type Z
An nSe contact layer, 97 is an Au / ZnTe contact layer, 98 is a p-type electrode, and 99 is an n-type electrode.

In the semiconductor lasers shown in FIGS. 8 and 9 as described above, the current is blocked by the polycrystalline ZnS layer 85 or the polyimide layer 95 and injected only into the mesa stripe portion. That is, the polycrystalline ZnS layer 85 and the polyimide layer 95 function as a current blocking layer. Further, when the ridge portion is formed by etching, the thickness of the clad layer 84 or the clad layer 94 other than the ridge portion is etched to a thickness insufficient for confining light. 85 or the polyimide layer 95 absorbs the light, and the light is guided only in the mesa stripe portion. As described above, the semiconductor lasers shown in FIGS. 8 and 9 are manufactured to have both the current confinement mechanism and the optical waveguide mechanism.

[0009]

However, the ridge type element structure using polyimide or polycrystalline ZnS for the current blocking layer as shown in FIGS. 8 and 9 has the following basic problems. ing.

In the semiconductor laser shown in FIG. 8, since polycrystallized ZnS is used for the current block layer, high-resistance polycrystallized ZnS can be reproduced with good reproducibility because of the treatment for polycrystallization. Hard to get. High resistance ZnS can be obtained even if it is made into a single crystal, but in this case, about 4.
There is a problem that a lattice mismatch of 3% occurs.

On the other hand, in the case of the semiconductor laser using the current blocking layer made of polyimide as shown in FIG. 9, a high temperature of at least 450 ° C. is required to polymerize the polyimide. A large strain is induced by the difference in the coefficient of thermal expansion, and residual stress occurs. Therefore,
Defects such as dislocations are likely to occur. Further, since the temperature for polymerizing the polyimide is far above the manufacturing temperature of the Group II-VI semiconductor of the periodic table, which is 250 to 350 ° C., diffusion of the dopant and the like is likely to occur.

Furthermore, since both semiconductor lasers use a material having a low thermal conductivity, the thermal resistance is high. Therefore, it is easy to cause the temperature rise of the semiconductor laser, high output,
It is difficult to obtain a semiconductor laser with a long life.

The present invention has been made in order to solve the above problems, and it is free from defects such as dislocations and residual stress due to lattice mismatch, and can be manufactured with high reproducibility. An object is to provide a semiconductor laser.

[0014]

A semiconductor laser according to the present invention is provided with a double heterostructure portion, in which both sides of an active layer are sandwiched by cladding layers, on a substrate, and one of the cladding layers has a ridge portion and A semiconductor laser in which both sides of a ridge portion are sandwiched by current blocking layers, wherein the double heterostructure portion is made of a periodic table II-VI group semiconductor material, and the current blocking layer is ZnS _x Te _1-x ( Since 0 <x ≦ 0.7), the above object is achieved thereby.

In one embodiment, the active layer is 2.3 eV.
ZnCdSe having the above bandgap energy
Compound, ZnSSe compound, ZnCdS compound, ZnS
e compound, MgZnCdS compound or MgZnCdS
e compound.

In one embodiment, the substrate is made of GaAs, the active layer has a bandgap energy of 2.6 eV or more, and the lattice mismatch with the GaAs substrate is within 0.3%. ZnSSe compound, ZnCd
It is composed of an S compound, a ZnSe compound or a MgZnCdS compound.

In one embodiment, the substrate is made of InP, and the active layer is made of a MgZnCdSe compound having a bandgap energy of 2.3 eV or more and having a composition lattice-matched with the InP substrate.

[0018]

Function: ZnS used for the current blocking layer in the present invention
_x Te _1-x (0 <x ≦ 0.7) is GaAs, ZnSe,
It is lattice-matched to a compound semiconductor substrate such as InP or InGaAsP. In addition, it emits blue to blue-green, that is, ZnSSe having a band gap energy of 2.3 eV or more,
ZnCdS, ZnSe, MgZnCdS, MgZnCd
It has low bandgap energy and high resistance to an active layer of Se or the like so that the function of confining current and light in the horizontal direction in the active layer can be sufficiently exerted. The reason will be described below.

FIG. 7 shows the dependence of the energy gap and the lattice constant of ZnS _x Te _{1-x on} the S composition _x .

Here, ZnMgSSe and ZnSe having compositions substantially lattice-matched to the GaAs substrate are used for the cladding layer and the active layer, respectively, and Z used for the current blocking layer.
Consider the case of nS _x Te _1-x . The ZnS _x Te _1-x current blocking layer has a GaA content when the S composition _x is x = 0.65.
s Substrate and ZnMgSSe cladding layer are lattice-matched. Further, the current gap layer having the composition of ZnS _0.65 Te _0.35 has an energy gap Eg of 2.6 eV,
It is smaller than the energy gap (Eg = 2.7 eV) of the Se active layer.

[0021] Thus, the ridge portion of the cladding layer present immediately above the active layer, by embedding the above ZnS _{0. 65} Te _0.35 current blocking layer, wherein the light is absorbed. Further, this current blocking layer is formed of ZnMgSSe as described above.
Since it is lattice-matched with the cladding layer, generation of dislocations, residual stress, etc. due to lattice mismatch can be suppressed. Also,
For the current confinement function, a high resistance ZnS _x Te _1-x current blocking layer is used, or a substrate or an active layer is applied so that a voltage in the direction opposite to the forward direction of the pn junction in the oscillation region is applied. If a ZnS _x Te _1-x current blocking layer having the same conductivity type as the lower clad layer is used, the same mechanism as the conventional one can be used.

As described above, the present invention uses ZnS _x Te _1-x as the current blocking layer, but the cladding layer and the active layer are made of InP, InGaAsP, etc. having a larger lattice constant than the GaAs substrate. It is also lattice-matched to the formed substrate. Also, the energy gap Eg of the active layer
For blue to blue-green light emission above 2.3 eV, the value of x of S composition _x in ZnS _x Te _1-x is 0.
If it is specified within the range of <x ≦ 0.7, it is possible to obtain a lattice constant that is substantially lattice-matched with these. Further, in that composition, the bandgap energy of ZnS _x Te _1-x is always less than or equal to the bandgap energy of the active layer. Furthermore, in the composition, ZnS _x Te _{1 -x} (0 <x
The feature is that conductivity type control of ≦ 0.7) or high resistance can be easily performed.

For the above reasons, the present invention provides a lattice matching system having both a current confinement mechanism and an optical waveguide mechanism,
A blue or blue-green semiconductor laser can be constructed.

[0024]

EXAMPLES Examples of the present invention will be described below. The present invention is not limited to the embodiments.

Example 1 FIG. 1 shows a blue-emitting semiconductor laser according to Example 1 of the present invention. As shown in FIG. 1, this semiconductor laser includes an n-type Mg _x substrate and an n-type Mg _x substrate.
An n-type cladding layer 2 made of Zn _y Cd _1-xy S is formed. The n-type cladding layer 2 has an elemental composition of 0.
22 <x ≦ 0.90, 0 <y ≦ 0.32, and the lattice constant thereof is that of the n-type GaAs substrate 1 (= 0.56).
5 nm).

On the n-type clad layer 2, Mg _x Zn _y
Cd _1-xy S (0 <x ≦ 0.64, 0.11 ≦ y ≦ 0.5
The active layer 3 of 0) is formed. Like this x
By selecting the compositions of y and y, the lattice constant of this active layer 3 substantially matches the lattice constant of the n-type GaAs substrate 1.

On the active layer 3, p-type Mg _x Zn _y C is formed.
d _1-xy S (0.22 <x ≦ 0.90, 0 <y ≦ 0.32)
The p-type clad layer 4 made of is formed. By selecting the composition of x and y in this way, the lattice constant of the p-type cladding layer 4 substantially matches the lattice constant of the n-type GaAs substrate 1. The p-type clad layer 4 has a structure having a ridge portion 10 whose both sides are etched.

A current blocking layer 5 made of n-type ZnS _0.65 Te _0.35 sandwiching the ridge portion 10 of the p-type cladding layer 4.
Are formed. The energy gap Eg ₃ of the n-type ZnS _0.65 Te _0.35 current blocking layer 5 is 2.60 eV, and the lattice constant is 0.565 nm, which matches the lattice constant of the GaAs substrate 1. A loss guide type semiconductor laser is constituted by having the ridge portion 10 and the current block layer 5 and the active layer 3 which embed the ridge portion.

A contact layer 6 made of, for example, p-type ZnSe is formed on the ridge portion 10 at the same height as the upper surface of the current block layer 5, and the contact layer 6 and the current block layer 5 are formed together. A contact layer 7 made of, for example, p-type ZnSe is formed on the above. A p-type electrode 9 is formed on the contact layer 7, and the n-type GaA is formed.
An n-type electrode 8 is formed on the s substrate 1 side.

Next, the fabrication of the semiconductor laser of this embodiment having the above structure will be described. In this example, the molecular beam epitaxy method (MBE) was used.

By doping Cl (chlorine) for the n-type layer and N (nitrogen) for the p-type layer, the contact layers 6 up to the n-type and the p-type, respectively, of the substrate wafer are formed. Layered one on top of the other.

Next, a stripe-shaped SiO ₂ mask was formed on the wafer thus grown by photolithography.

Next, the p-type contact layer 6 portion which is not covered with this SiO ₂ mask is etched into a mesa by an etching solution, and subsequently, the p-type clad layer 4 on the upper side is brought to a predetermined thickness position. The ridge portion 10 was formed by etching in a mesa shape.

Next, with the SiO ₂ mask attached, MB
A second growth was performed by the E method to form an n-type ZnSTe layer as the current blocking layer 5.

Next, the SiO ₂ mask was removed by etching and the third growth was performed to form the p-type contact layer 7. The growth conditions of the second and third MBE methods are almost the same as the growth conditions of the first time.

Finally, both p-type and n-type electrodes 8 and 9 were formed, and cleaved to a cavity length of 250 μm to separate them into individual chips. The ohmic electrode 8 of the n-type GaAs substrate 1 is In, and the ohmic electrode 9 of the p-type contact layer 7 is Au.
-Cr was formed by vacuum vapor deposition.

In the semiconductor laser of the first embodiment, the energy gap Eg of the active layer 3 is 3.0 eV to 3.9 eV, while the energy gap Eg of both clad layers 2 and 4 is larger than the Eg of the active layer. It is 3.3 eV to 4.2 eV, which is higher than 0.3 eV. This difference is a value that can ensure a sufficient band discontinuity for laser oscillation, and is about 320 to 4
An oscillation wavelength of 13 nm was obtained. The energy gap Eg of the current blocking layer 5 is 2.60 eV, and the energy gap Eg of the active layer 3 (= 3.0 eV to 3.9 eV).
V), which is smaller than V) and is directly above the active layer 3
Fully absorbs the light that seeps out. Furthermore, the lattice constants of the n-type and p-type cladding layers 2 and 4 and the current blocking layer 5 match the lattice constant of the GaAs substrate 1, and the lattice constant of the active layer 3 also matches the GaAs substrate 1 well. It is possible to obtain a high quality ridge type double hetero structure portion which is not easily deteriorated.

Example 2 In Example 2, the active layer had an energy gap of 2.8 eV and GaAs.
Zn _0.42 Cd _0.58 S that is lattice-matched with the substrate was used, and the configuration and manufacturing method of the other layers were the same as in Example 1. Moreover, the same numbers are given to the same portions, and the same applies to the other embodiments described below.

FIG. 2 shows a semiconductor laser of the second embodiment.
In this semiconductor laser, each of the n-type and p-type cladding layers 12 and 14 has the same Mg _x Zn _y Cd _1-xy as in the first embodiment.
Although it was formed of S, its elemental composition was selected such that x and y were such that the energy gap Eg ₂ was Eg ₂ ≧ 3.1 eV and the lattice constant thereof matched the lattice constant of the GaAs substrate 11. .

The active layer 13 has an energy gap E
The g _{1 is set} to 2.8 eV, which is smaller than the energy gap Eg ₂ (≧ 3.1 eV) of the clad layers 12 and 14 by 0.3 eV or more. Energy gap Eg ₃ of the current blocking layer 15
(= 2.60 eV) is smaller than the energy gap Eg ₁ (= 2.8 eV) of the active layer 13.

In the semiconductor laser of the second embodiment having the above-mentioned structure, both clad layers 12,
14, the lattice constants of the active layer 13 and the current blocking layer 15 match the lattice constants of the GaAs substrate 1 and are lattice-matched. In addition, the energy gap Eg ₁ (2.
8 eV) is smaller than the energy gap Eg ₂ (≧ 3.1 eV) of the cladding layers 12 and 14 by 0.3 eV or more, and is a value capable of ensuring a band discontinuity sufficient to cause laser oscillation, and an oscillation wavelength of about 460 nm. Got Further, the energy gap Eg ₃ (= 2.60e of the current blocking layer 15)
V) is the energy gap Eg ₁ (= 2.8 of the active layer 13)
It is smaller than eV) and is a sufficient value to absorb the light exuded to the p-type cladding layer 14 above the active layer 13. Further, the lattice constants of both the clad layers 12 and 14 and the current blocking layer 15 are the lattice constants of the GaAs substrate 11 (=
0.565 nm), so that the device is of high quality and is not easily deteriorated.

(Example 3) Example 3 is a case where an InP substrate is used.

FIG. 3 shows a semiconductor laser of the third embodiment.
This semiconductor laser was manufactured by the same process as in Example 1.

In FIG. 3, 21 is an InP substrate. On this InP substrate 21, n-type Mg _x Zn _y Cd _1-xy Se (0.23 <x ≦, which matches the lattice constant of InP, is formed.
An n-type clad layer (barrier layer) 22 of 0.95, 0.05 ≦ y ≦ 0.37) is formed. On the n-type clad layer 22, Mg _x having a lattice constant substantially equal to that of InP is formed.
Zn _y Cd _1-xy Se (0 <x ≦ 0.69, 0.18 ≦ y ≦
An active layer 23 of 0.50) is formed. On the active layer 23, a p-type M matching the lattice constant of InP is formed.
g _x Zn _y Cd _1-xy Se (0.23 <x ≦ 0.95, 0.0
5 ≦ y ≦ 0.37) p-type cladding layer (barrier layer)
24 are formed. As described above, for the n-type and p-type clad layers 22 and 24 and the active layer 23, Mg _x Zn _y Cd _1-xy Se is used, and the elemental composition of the active layer 23 is 0 < x ≦ 0.69, 0.18
≦ y ≦ 0.50, and the elemental composition of the cladding layer was 0.23 <x ≦ 0.95 and 0.05 ≦ y ≦ 0.37.
In such a composition, the cladding layers 22 and 24 and the active layer 23 are well lattice-matched to the InP substrate 21.

The current blocking layer 25 filling the ridge portion of the clad layer 24 is made of n-type ZnS _0.34 Te _0.66 and has a lattice constant of 0.5869 nm, which matches the lattice constant of the InP substrate 21.

In the thus constructed semiconductor laser of the third embodiment, the energy gap Eg ₂ of the cladding layers 22 and 24 is 2.6 eV to 3.5 eV, and the active layer 2
Energy gap Eg _{1 of} 3 (from 2.3 eV to 3.2 e
V) more than 0.3eV higher. This difference ensures a band discontinuity sufficient for laser oscillation, and is about 387.
An oscillation wavelength of ˜540 nm was obtained. The energy gap Eg ₃ of the current blocking layer 25 is 2.12 eV, and the energy gap Eg ₁ (2.3 eV of the active layer 23 is
To 3.2 eV), which is low enough to absorb the light exuded to the p-type cladding layer 24 on the active layer 23. Furthermore, both the n-type and p-type clad layers 22, 24
Also, since the lattice constant of the current blocking layer 25 matches the lattice constant of InP, the device is of high quality and is not easily deteriorated.

(Embodiment 4) FIG. 4 shows a semiconductor laser of the present embodiment 4. In this semiconductor laser, n-type GaA
On the s substrate 31, the lattice constant of GaAs is 0.565 nm
N-type Zn _x Mg _1-x S _y Se _1-y (0.85 <x
An n-type clad layer (barrier layer) 32 composed of ≦ 1.0, 0.06 ≦ y ≦ 0.35) is formed. On the n-type cladding layer 32, a ZnSe active layer 33 having a lattice constant substantially equal to that of GaAs is formed. Furthermore, the active layer 3
On top of p-type Zn _x Mg _1-x S _y Se _1-y (0.85 <
A p-type cladding layer (barrier layer) 34 composed of x ≦ 1.0 and 0.06 ≦ y ≦ 0.35) is formed. The current blocking layer 35 filling the ridge portion of the p-type cladding layer 34 is made of Zn.
It consists of S _0.65 Te _0.35 . This ZnS _0.65 Te _{0.35 has} an energy gap Eg ₃ of 2.60 eV and a lattice constant of 0.5.
It matches the lattice constant of the GaAs substrate 31 at 65 nm.

In the thus constructed semiconductor laser device of Example 4, both the n-type and p-type cladding layers 3 are formed.
The lattice constants of the layers 2, 34, the active layer 33, and the current blocking layer 35 match the lattice constant of the GaAs substrate 31 and are lattice-matched. In addition, both the n-type and p-type cladding layers 32 and 34
Energy gap Eg ₂ of 3.0ev to 3.5eV
Then, the energy gap Eg ₁ (=
It is higher than 2.7 eV) by 0.3 eV or more, and a band discontinuity sufficient for laser oscillation can be secured, and an oscillation wavelength of about 460 nm was obtained. Further, the energy gap Eg ₃ (= 2.60 eV) of the current blocking layer 35 is smaller than the energy gap Eg ₁ of the active layer 33, and absorbs the light leaked to the p-type cladding layer 34 on the active layer 33. Large enough for Further, both n-type and p-type clad layers 32, 34
And the lattice constant of the current blocking layer 35 is the GaAs substrate 31.
Since it matches that of, it will be of high quality that is not easily deteriorated.

(Embodiment 5) FIG. 5 shows a semiconductor laser of the present embodiment 5. In Example 5, the active layer, the energy gap Eg ₁ is 2.8 eV, ZnS ₀ of Composition GaAs substrate lattice matched _.06 Se _0.94 or Zn _0.42 Cd _0.58
S is used.

The semiconductor laser of Example 5 is an n-type, p-type.
The type clad layers 42 and 44 are made of Z as in the device of the fourth embodiment.
It was formed of an n _x Mg _1-x S _y Se _1-y compound, and its composition was such that the energy gap Eg _{2 of the} n-type and p-type cladding layers 42 and 44 was Eg ₂ ≧ 3.1 eV. , Y values were selected. The active layer 43 has an energy gap Eg ₁
There are 2.8 eV, is used ZnS _0.06 Se _{0.9 4} or Zn _0.42 Cd _0.58 S having a composition lattice-matched with GaAs substrate 41.

In the semiconductor laser of the fifth embodiment, the cladding layers 42, 44, the active layer 43 and the current blocking layer 45 are well lattice-matched to the n-type GaAs substrate 41. Further, the energy gap Eg ₁ of the active layer 43 is smaller than the energy gap Eg ₂ of the n-type and p-type cladding layers 42 and 44 by 0.3 eV or more, so that a band discontinuity sufficient for laser oscillation can be secured, and about 440 nm. The oscillation wavelength of was obtained. Further, since the energy gap Eg ₃ (= 2.60 eV) of the current blocking layer 45 is smaller than the energy gap Eg ₁ of the active layer 43, the active layer 43
The height is low enough to absorb the light oozing into the p-type cladding layer 44 immediately above. In addition, the cladding layers 42 and 44 and the current blocking layer 45 have the same lattice constant as the n-type GaAs substrate 41, and are of high quality that are not easily deteriorated.

(Sixth Embodiment) FIG. 6 shows a semiconductor laser of the sixth embodiment. In this Example 6, manufacturing was performed by the same process as in Example 1.

In this semiconductor laser, n-type GaA is used.
On the s substrate 51, the GaAs lattice constant (0.565n
The n-type cladding layer (barrier layer) 52 made of n-type Zn _0.42 Cd _0.58 S, which is the same as that of m), is formed. The energy gap Eg of the n-type cladding layer 52 is about 2.8 eV.

On the n-type cladding layer 52, a ZnSe active layer 53 having a lattice constant substantially equal to that of GaAs is formed. The energy gap Eg of the ZnSe active layer 53 is about 2.7 eV.

On the active layer 53, a p-type clad layer (barrier layer) 54 made of p-type Cu ₅ Al (S _0.06 Se _0.94 ) _{4 having} a lattice constant of GaAs is formed. The energy gap Eg of the p-type clad layer 54 is about 3.3 eV.
Is.

The current blocking layer 55 filling the ridge portion of the p-type cladding layer 54 is formed of high resistance ZnS _0.65 Te _0.35 . The high-resistance ZnS _0.65 Te _0.35 current block layer 55 has an energy gap Eg of 2.6 eV, a lattice constant of 0.565 nm, and a GaAs substrate 51.
Matches

In the thus constructed semiconductor laser of Example 6, the cladding layers 52, 54 and the active layer 53 are formed.
And each of the current blocking layers 55 is an n-type GaAs substrate 5
It is well lattice matched to 1. The energy gap Eg ₃ of the current blocking layer 55 is 2.60 eV, and the active layer 5
3 is smaller than the energy gap Eg ₁ (= 2.7 eV) of 3 and is sufficient to absorb the light leaked to the p-type cladding layer 54 above the active layer 53. Further, the energy gap Eg of the n-type clad layer 52 and the p-type clad layer 54 is
Are 2.8 eV and 3.3 eV, respectively, and ZnSe active layer 5
Higher than the energy gap Eg of 3 (= 2.7 eV),
It is possible to secure sufficient band discontinuity for laser oscillation.
An oscillation wavelength of 0 nm was obtained. Further, the lattice constants of both the n-type and p-type cladding layers 52 and 54 and the current blocking layer 55 are the same as those of the GaAs substrate 51, so that the device is of high quality and is not easily deteriorated.

In each of the above-mentioned embodiments, the structure using the n-type substrate is shown. However, when the p-type substrate is used, as a matter of course, the p-type clad layer, the active layer and the n-type are formed on the p-type substrate. In this case, the type clad layer and the p-type or high resistance current blocking layer are laminated in this order, and the above-described effects of the present invention can be obtained in this case as well.

In the present invention, it is possible to use Ga as the n-type dopant in place of Cl (chlorine) and O (oxygen) as the p-type dopant in place of N (nitrogen).

The present invention is also applicable to a photo-excitation double heterojunction type semiconductor laser device.

Although InP and GaAs are selected as the substrate in the above embodiment, the present invention is not limited to this, and an InGaAsP substrate or the like can be used. When an InGaAsP substrate or the like is used, ZnS _x Te _1-x is used within a range that satisfies the requirements of the present invention.
The composition of the S element of the current blocking layer can be selected.

The present invention also relates to the manufacturing method in MB.
It is also possible to use the induced metal vapor phase epitaxy (MOCVD) which is excellent in composition controllability and crystallinity as in the E method.

[0063]

As described above, according to the present invention, the following effects can be obtained in the semiconductor laser device using the II-VI group semiconductor of the periodic table.

(1) ZnS _x Te _1-x (0 <X ≦ 0.7) used in the current blocking layer for embedding the ridge portion is smaller than the II-VI group semiconductor active layer forming the blue oscillation region. Since it has an energy gap, optical guiding by a loss guide is possible and a stable fundamental transverse mode can be realized.

(2) ZnS _x Te _1-x layer (0 <X ≦ 0.
7) is an active layer formed of a II-VI group semiconductor of the periodic table,
Since it is lattice-matched with the clad layer and the substrate, defects such as dislocations and residual stress due to lattice mismatch, which have been conventionally problems, do not occur. Therefore, even if laser oscillation is performed for a long time, the semiconductor laser element is hardly deteriorated and has a long life and high reliability.

(3) All semiconductor layers constituting the device, including the current blocking layer, can be manufactured consistently at almost the same temperature by the MBE method or MOCVD method. Conventionally, because of the polyimide polymerization step and the ZnS polycrystallization step, the productivity is not as bad as when the conditions have to be changed during the manufacturing process, and there is no deterioration of the light emitting layer accompanying it. . Therefore, a highly reliable semiconductor laser device having high quality and uniform characteristics can be manufactured with high mass productivity and at low cost over a wide range of the effective area of the device.

(4) ZnS _x Te _1-x layer (0 <X ≦ 0.
Since 7) has an extremely high resistance, there is almost no leakage current to the outside of the oscillation region, and oscillation with a low threshold current is possible. Therefore, the semiconductor laser generates less heat, and mounting on a heat sink becomes easier.

[Brief description of drawings]

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

FIG. 2 is a sectional view of a semiconductor laser device of Example 2.

FIG. 3 is a sectional view of a semiconductor laser device of Example 3.

FIG. 4 is a sectional view of a semiconductor laser device of Example 4.

FIG. 5 is a sectional view of a semiconductor laser device of Example 5.

FIG. 6 is a sectional view of a semiconductor laser device of Example 6.

FIG. 7 is a diagram showing the elemental composition dependence of the energy gap and the lattice constant in ZnS _x Te _1-x .

FIG. 8 is a diagram showing a conventional example.

FIG. 9 is a diagram showing another conventional example.

[Explanation of symbols]

1, 11, 31, 41, 51 GaAs substrate 21 InP substrate 2, 4, 12, 14 MgZnCdS clad layer 22, 24 MgZnCdSe clad layer 32, 34, 42, 44 ZnMgSSe clad layer 52 ZnCdS clad layer 54 CuAl (SSe) clad Layer 3 MgZnCdS active layer 13 ZnCdS active layer 43 ZnSSe or ZnCdS active layer 23 MgZnCdSe active layer 33, 53 ZnSe active layer 5, 15, 25, 35, 45, 55 ZnSTe current blocking layer 6, 7 Contact layer 8, 9 Electrode 10 Ridge part

Claims (4)

[Claims] 1. A double heterostructure portion is provided on a substrate, wherein both sides of an active layer are sandwiched by cladding layers, and one of the cladding layers has a ridge portion and both sides of the ridge portion are sandwiched by current blocking layers. In this semiconductor laser, the double heterostructure portion is made of a II-VI group semiconductor material of the periodic table, and the current blocking layer is ZnS _x Te _1-x (0 <x ≦
A semiconductor laser composed of 0.7). 2. The ZnCdSe compound, ZnS, wherein the active layer has a bandgap energy of 2.3 eV or more.
Se compound, ZnCdS compound, ZnSe compound, Mg
The semiconductor laser according to claim 1, comprising a ZnCdS compound or a MgZnCdSe compound. 3. A ZnSSe compound having a composition in which the substrate is made of GaAs, the active layer has a band gap energy of 2.6 eV or more, and the lattice mismatch with the GaAs substrate is within 0.3%. ZnCdS compound, Z
The semiconductor laser according to claim 1, comprising an nSe compound or a MgZnCdS compound. 4. The substrate is made of InP, and the active layer has a bandgap energy of 2.3 eV or more.
In addition, MgZnCdS having a composition that lattice-matches the InP substrate
The semiconductor laser according to claim 1, which is composed of an e compound.