JPH05121835A - Semiconductor laser device and manufacturing method - Google Patents

Abstract

PURPOSE:To provide a semiconductor laser device, along with its manufacturing method, in which a shorter oscillating wavelength is realized at low threshold operation without deteriorating laser characteristics. CONSTITUTION:A semiconductor laser device comprises a buffer layer 2, a photo waveguide layer 3, an activated luminescent layer 4, a photo waveguide layer 5, a buffer layer 6, a current constriction and photo absorbent layer 7, and a contact layer 8, each formed on an n-type GaAs substrate 1. In the semiconductor laser device, an impurity is contained in at least one layer out of a quantum well layer and a quantum barrier layer that constitute the activated luminescent layer 4. Moreover, at least the activated luminescent layer is grown in an organic metal vapor phase growth method or a molecular beam epitaxial growth method.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a short wavelength visible semiconductor laser device suitable for an optical information terminal, a light source for optical application measurement, etc., and a method for manufacturing the same.

[0002]

2. Description of the Related Art A conventional semiconductor laser device has a double hetero structure in which bulk AlGaInP doped with impurities is used as a light emitting active layer as described in, for example, Japanese Patent Laid-Open No. 63-124592. The laser oscillation wavelength was shortened by about 20 nm due to the doping.

On the other hand, Applied Physics Letter, Vol. 50, p. 1033 (1987) (Appl. Ph.
ys. Lett. , Vol20. , Pp1033 (19
87)) describes a semiconductor laser device having a light emitting active layer having a quantum well structure.

[0004]

In the above-mentioned conventional technique, the active region is doped with a high concentration of impurities, resulting in an increase in defects and a decrease in light emission efficiency, and in addition, an increase in optical loss due to free carriers. There is a problem that the threshold current is increased and the reliability is lowered. Moreover, it was not clear about the impurity concentration level that does not impair the laser characteristics. Furthermore, the doping of impurities when the light emitting active layer has a quantum well structure has not been described, and the design of the quantum well structure for obtaining short-wavelength laser oscillation has not been clarified.

The object of the present invention is to oscillate at a short wavelength,
It is an object of the present invention to provide a semiconductor laser device which operates at a low threshold current and has a quantum well structure introduced in a light emitting active layer.

Another object of the present invention is to provide a method of manufacturing such a semiconductor laser device.

[0007]

The above-mentioned objects are (1) (A
l _y Ga _1-y ) _a In _1-a P (where y and a are 0 <
y ≦ 1, 0.3 ≦ a ≦ 0.8), and a double heterojunction sandwiching a light emitting active layer having a smaller forbidden band than the optical waveguide layer having a large forbidden band. In the semiconductor laser device on the semiconductor substrate, the light emitting active layer is (Al _x1 Ga _{1 -x1} ) _a In _1-a P (where x ₁ is a value in the range of 0 ≦ x ₁ <y, and a is A quantum well layer of (Al _x2 Ga _{1 -x2} ) _a I
n _1-a P (where x ₂ is a value in the range of x ₁ <x ₂ <y,
a is a value in the above range) and a quantum barrier layer consisting of at least a multiple quantum well structure,
And a semiconductor laser device characterized by having an impurity in quantum barrier _{layer, (2) (Al y Ga} 1-y) a In 1-a P
(However, y and a are 0 <y ≦ 1 and 0.3 ≦ a ≦, respectively.
A semiconductor laser device having a double heterojunction on a semiconductor substrate with a light-emission active layer having a smaller forbidden band width by an optical waveguide layer having a larger forbidden band width, which is a value in the range of 0.8). The light emitting active layer is formed of (Al _x1 Ga
_1-x1 ) _a In _1-a P (where x ₁ is a value in the range of 0 ≦ x ₁ <y, and a is a value in the above range), and (Al _x2 Ga _{1 -x2} ) _a In _1-a P (where x ₂ is x ₁
<X ₂ <y, and a is a value in the above range). A quantum barrier layer is repeatedly provided, and an impurity is added to the quantum well layer. A semiconductor laser device having (3)
(Al _y Ga _1-y ) _a In _1-a P (where y and a are values in the range of 0 <y ≦ 1 and 0.3 ≦ a ≦ 0.8, respectively) and have a large forbidden band width. In a semiconductor laser device having a double heterojunction on a semiconductor substrate in which a light emitting active layer having a smaller forbidden band width is sandwiched by an optical waveguide layer, the light emitting active layer comprises (Al _x1 Ga _{1 -x1} ) _a In _{1 -a} P (but x
₁ is a value within the range of 0 ≦ x ₁ <y, and a is a value within the above range), and a quantum well layer (Al _x2 Ga _{1 -x2} ) _a
And _a quantum barrier layer made of In _{1 -a} P (where x ₂ is a value in the range of x ₁ <x ₂ <y, and a is a value in the above range). (4) The above-mentioned 1, wherein the semiconductor laser device has at least an impurity in the quantum well layer and the quantum barrier layer.
In the semiconductor laser device according to 2 or 3, the light emitting active layer further comprises (Al _{x2) on} both sides of the multiple quantum well structure.
Ga _1-x2 ) _a In _1-a P (where x ₂ is a value in the range of x ₁ <x ₂ <y, where x ₁ is a value in the above range, and a
Is a value within the above range), a semiconductor laser device having a light confinement layer of (5). In the semiconductor laser device according to any one of 1 to 4 above,
X ₂ in the composition (Al _x2 Ga _1-x2 ) _a In _1-a P of the quantum barrier layer is set to a value in the range of 0.4 ≦ X ₂ ≦ 0.7, a semiconductor laser device, (6) 1 to 5 above
In the semiconductor laser device according to any one of items 1 to 5, the band edge energy of the quantum barrier layer is 0.2 eV or more higher than that of the quantum well layer, (7) From 1 above in the semiconductor laser device according to any one of 6, the thickness of the quantum barrier layer, a semiconductor laser device which is a range of _{4~8nm, (8) (Al y} Ga 1-y) a An optical waveguide layer having a large forbidden band width of In _1-a P (where y and a are values in the range of 0 <y ≦ 1 and 0.3 ≦ a ≦ 0.8, respectively) provides a forbidden band. In a semiconductor laser device having a double heterojunction sandwiching a light emitting active layer having a small width on a semiconductor substrate, the upper part of the optical waveguide layer above the light emitting active layer is:
The light emitting active layer has a stripe-shaped convex portion in the emitting direction of laser light, and a current confinement and light absorption layer on both sides of the convex portion, and the light emitting active layer is (Al _x1 Ga _{1 -x1} ) _a In _{1 -a} P (However, x ₁ is 0 ≦
x ₁ <y, where a is a value in the above range), and (Al _x2 Ga _{1 -x2} ) _a In
_1-a P (where x ₂ is a value in the range of x ₁ <x ₂ <y, and a
A semiconductor laser device having at least a multiple quantum well structure in which a quantum barrier layer having a value within the above range) is repeatedly provided, and having an impurity in the quantum barrier layer, (9) (Al _y Ga _1-y ) _a In _1-a P (where y and a are 0 <y ≦ 1 and 0.3 ≦ a ≦ 0.8, respectively)
A semiconductor laser device having a double heterojunction on a semiconductor substrate with a light-emitting active layer having a smaller forbidden band width than that of an optical waveguide layer having a large forbidden band width. The upper portion of the optical waveguide layer on the upper side of the layer has a stripe-shaped convex portion in the emitting direction of laser light,
Both sides of the convex portion have a current confinement and light absorption layer, and the light emitting active layer is (Al _x1 Ga _{1 -x1} ) _a In _{1 -a} P (where x ₁ is a value in the range of 0 ≦ x ₁ <y And a is a value within the above range), and (Al _x2 Ga _{1 -x2} ) _a I
n _1-a P (where x ₂ is a value in the range of x ₁ <x ₂ <y,
a is a value within the above range) and a quantum barrier layer consisting of at least a multiple quantum well structure,
And a semiconductor laser device characterized by having an impurity in the quantum well _{layer, (10) (Al y Ga} 1-y) a In 1-a P
(However, y and a are 0 <y ≦ 1 and 0.3 ≦ a ≦, respectively.
A semiconductor laser device having a double heterojunction on a semiconductor substrate with a light-emission active layer having a smaller forbidden band width by an optical waveguide layer having a larger forbidden band width, which is a value in the range of 0.8). The upper part of the optical waveguide layer on the upper side of the light emitting active layer has a stripe-shaped convex portion in the emitting direction of laser light, and both sides of the convex portion have a current constriction and light absorbing layer, and the light emitting active layer is (Al _x1 Ga _1-x1 ) _a In _1-a P (where x ₁ is a value in the range of 0 ≦ x ₁ <y, and a is a value in the above range); Al _x2 Ga _1-x2 )
Multiple quantum well structure in which a quantum barrier layer made of _a In _1-a P (where x ₂ is a value in the range of x ₁ <x ₂ <y and a is a value in the above range) is repeatedly provided. And a quantum well layer and an impurity in the quantum barrier layer. (11) In the semiconductor laser element according to the above 8, 9 or 10, the light emitting active layer comprises: , (Al _x2 Ga _{1 -x2} ) _a In _{1 -a} P (where x ₂ is x ₁ <x ₂ ) on both sides of the above multiple quantum well structure.
<A value in the range of y, where x ₁ is a value in the above range, and a is a value in the above range).
2) In the semiconductor laser device described in any one of 8 to 11, the composition of the quantum barrier layer (Al _x2 G
a _1-x2 ) _a In _1-a P has X ₂ of 0.4 ≦ X ₂ ≦ 0.
(13) In the semiconductor laser device according to any one of (8) to (12) above, the band edge energy of the quantum barrier layer is equal to that of the quantum well layer. A semiconductor laser device characterized by being 0.2 eV or more larger than that, (14) In the semiconductor laser device according to any one of 8 to 13 above, the thickness of the quantum barrier layer is in the range of 4 to 8 nm. It is achieved by a semiconductor laser device characterized in that

[0008] The above other objects, (15) on a semiconductor _{substrate, (Al y Ga 1-y} ) a In 1-a P ( except y, a are each 0 <y ≦ 1,0.3 ≦ a ≦ Forming a light-guiding layer having a value in the range of 0.8) (Al _x1 Ga
_1-x1 ) _a In _1-a P (where x ₁ is a value in the range of 0 ≦ x ₁ <y, and a is a value in the above range), and (Al _x2 Ga _{1 -x2} ) _a In _1-a P (where x ₂ is x ₁
A value in the range <x ₂ <y, where a is a value in the above range) is repeatedly provided to form a multiple quantum well structure that constitutes a light emitting active layer;
_y Ga _1-y ) _a In _1-a P (where y and a are values in the above ranges, respectively), and a step of forming an optical waveguide layer. The well layer and the quantum barrier layer are formed by a metal organic chemical vapor deposition method, and the quantum barrier layer is doped with an impurity. (16) A method for manufacturing a semiconductor laser device, Al _y Ga _1-y ) _a In
_1-a P (where y and a are 0 <y ≦ 1 and 0.3 ≦, respectively)
a step of forming an optical waveguide layer consisting of a ≦ 0.8, and (Al _x1 Ga _1-x1 ) _a In _1-a P (where x
₁ is a value within the range of 0 ≦ x ₁ <y, and a is a value within the above range), and a quantum well layer (Al _x2 Ga _{1 -x2} ) _a
A quantum barrier layer made of In _1-a P (where x ₂ is a value in the range of x ₁ <x ₂ <y and a is a value in the above range) is repeatedly provided to form a light emitting active layer. forming a multiple quantum well structure, and forming a light waveguide layer made of _{(Al y Ga 1-y)} a in 1-a P ( except y, a are each a value within the above range) In the method for producing a semiconductor laser device having at least the quantum well layer and the quantum barrier layer, the quantum well layer is formed by a metal organic chemical vapor deposition method, and the quantum well layer is doped with impurities. production method, (17) on a semiconductor _{substrate, (Al y Ga 1-y} ) a in 1-a P ( except y, a are each 0 <ranging y ≦ 1,0.3 ≦ a ≦ 0.8 Value of the optical waveguide layer is formed, and (Al _x1 Ga
_1-x1 ) _a In _1-a P (where x ₁ is a value in the range of 0 ≦ x ₁ <y, and a is a value in the above range), and (Al _x2 Ga _{1 -x2} ) _a In _1-a P (where x ₂ is x ₁
A value in the range <x ₂ <y, where a is a value in the above range) is repeatedly provided to form a multiple quantum well structure that constitutes a light emitting active layer;
_y Ga _1-y ) _a In _1-a P (where y and a are values in the above ranges, respectively), and a step of forming an optical waveguide layer. The well layer and the quantum barrier layer are formed by a metal organic chemical vapor deposition method, and the quantum well layer and the quantum barrier layer are doped with impurities. (18) The method for producing a semiconductor laser device, 15, 16 or 1
7. The method for manufacturing a semiconductor laser device according to claim 7, wherein the metalorganic vapor phase epitaxy is performed at a growth temperature in the range of 650 to 750 ° C.,
(19) on a semiconductor _{substrate, (Al y Ga 1-y} ) a In 1-a P
(However, y and a are 0 <y ≦ 1 and 0.3 ≦ a ≦, respectively.
(Al _x1 Ga _1-x1 ) _a In _1-a P (where x ₁ is a value in the range of 0 ≦ x ₁ <y And a is a value within the above range), and (Al _x2 Ga _{1 -x2} ) _a I
n _1-a P (where x ₂ is a value in the range of x ₁ <x ₂ <y,
a is provided repeatedly and quantum barrier layers composed of a is) the value of the above range, forming a multiple quantum well structure forming the light-emitting active _{layer, (Al y Ga 1-y} ) a In 1-a P (Where y and a are values in the above ranges, respectively). In the method for manufacturing a semiconductor laser device, the quantum well layer and the quantum barrier layer are molecular beam epitaxy. Forming the quantum barrier layer and doping the quantum barrier layer with an impurity. (20) On a semiconductor substrate,
(Al _y Ga _1-y ) _a In _1-a P (where y and a are values in the range of 0 <y ≦ 1 and 0.3 ≦ a ≦ 0.8, respectively) are formed. And the process (Al _x1 Ga _1-x1 )
_a In _1-a P (where x ₁ is a value in the range of 0 ≦ x ₁ <y and a is a value in the above range), and (Al _x2 Ga _{1 -x2} ) _a In _1-a P (where x ₂ is x ₁ <
x ₂ <y in the range, a is a value in the above range) and a quantum barrier layer are repeatedly provided to form a multiple quantum well structure constituting the light emitting active layer;
_y Ga _1-y ) _a In _1-a P (where y and a are values in the above ranges, respectively), and a step of forming an optical waveguide layer. well layer and the quantum barrier layer is formed by molecular beam epitaxy, and a method of manufacturing a semiconductor laser device characterized by doping impurities into the quantum well layer, the (21) on a semiconductor substrate, (Al _y Ga _1-y ) _a I
n _1-a P (where y and a are 0 <y ≦ 1 and 0.3, respectively)
≦ a ≦ 0.8) and a (Al _x1 Ga _1-x1 ) _a In _1-a P (where x ₁ is 0 ≦ x ₁ <y A value in the range, a is a value in the above range), and a (Al _x2 Ga _{1 -x2} )
_a quantum barrier layer composed of _a In _1-a P (where x ₂ is a value in the range of x ₁ <x ₂ <y and a is a value in the above range) is repeatedly provided to form a light emitting active layer. forming a multiple quantum well structure, a step of forming a light waveguide layer made of _{(Al y Ga 1-y)} a in 1-a P ( except y, a are each a value within the above range) In the method for manufacturing a semiconductor laser device having at least, the quantum well layer and the quantum barrier layer are formed by a molecular beam epitaxy method, and the quantum well layer and the quantum barrier layer are doped with impurities. A method for manufacturing a semiconductor laser device,
(22) In the method of manufacturing a semiconductor laser device according to the above 19, 20 or 21, the molecular beam epitaxy method is
This can be achieved by a method for manufacturing a semiconductor laser device, which is performed at a growth temperature of 500 to 600 ° C.

[0009] The value of a in the composition _{(Al y Ga 1-y)} a In 1-a P material of each layer of the semiconductor laser device of the present invention,
Although it can be used in the range of 0.3 to 0.8,
The value of a is preferably determined so that the lattice constant of each layer matches the lattice constant of the substrate. For example, when a GaAs substrate is used as the substrate, a is preferably 0.51, and when a GaAsP substrate is used as the substrate, a is preferably 0.7.

As the impurity species to be doped in the light emitting active layer, the p-type impurity species is preferably Zn, Mg or Be,
The n-type impurity species are preferably Si or Se. The concentration of these impurities is 5 × 10 ¹⁷ to 2 × 10 ¹⁸ c in the case of Zn.
m to ³ range, maximum range of 5 × 10 ¹⁸ cm to ³ for Mg, maximum range of 1 × 10 ¹⁹ cm to ³ for Be, and 5 × 10 ¹⁷ to 2 × 10 ¹⁸ cm for Si. range of ^1-3, preferably in a range of up to 5 × 10 ¹⁸ cm - ³ in the case of Se.

Each layer of the semiconductor laser device of the present invention, especially the light emitting active layer, is preferably formed by epitaxial growth by a metal organic chemical vapor deposition method or a molecular beam epitaxy method. The organometallic vapor phase epitaxy method uses an organic aluminum compound as an Al raw material, for example, an alkylaluminum compound such as trimethylaluminum, an organic gallium compound as a Ga raw material, for example, an alkylgallium compound such as trimethylgallium, an indium compound as an In raw material, For example, an alkylindium compound such as trimethylindium, phosphine is used as a raw material for P, and a growth temperature is 650 ° C. to 750 ° C., a constant pressure or 50 Torr to 100 T.
It is preferable to carry out at a reduced pressure of orr. When the pressure is reduced, it is more preferable to carry out at 70 Torr to 80 Torr.

When Zn is used as the p-type impurity for doping the light emitting active layer, an organozinc compound, for example, an alkylzinc compound such as dimethylzinc, is used, and when Mg is used, an organomagnesium compound, for example, an alkylmagnesium such as dimethylmagnesium. When Be is used as the compound, an organic beryllium compound, for example, an alkyl beryllium compound such as dimethyl beryllium is added to the raw material. Also,
When Si and Se are used as n-type impurities, phosphine and hydrogen selenide are added to the raw materials, respectively.

The molecular beam epitaxy method uses A as a raw material.
l, Ga, In, and phosphine or P as a raw material of P
Is preferably used at a growth temperature of 500 ° C to 600 ° C. The pressure is 10 to 10 when P is used as a raw material for P.
It is preferable to carry out at ¹⁰ Torr to ¹⁰ to ¹¹ Torr,
When using phosphine as a raw material of P, it is 10 to ⁵ Tor.
It is preferable to carry out at r.

[0014]

[Action] The operation of the present invention will be described as an example epitaxially grown quaternary mixed crystal was _{(Al y Ga 1-y)} a In 1-a P on a GaAs substrate. The value of a for making this mixed crystal lattice-matched with the substrate is 0.51. Now, (AlGa) _0.51
The In _0.49 P mixed crystal has an ordered arrangement structure of group III elements and has a small band gap energy. In the present invention,
The band gap energy of the active layer is increased by suppressing the ordered arrangement structure of the group III elements in the (AlGa) _0.51 In _0.49 P mixed crystal by impurity doping.

However, for example, Japanese Journal of Applied Physics, Vol. 28 (1
989) L2092-L2094 (Jpn J.A.
ppl. Phys. , 28 (1989) L2092-L
2094), it is known that the emission intensity may decrease due to impurity doping. It is considered that this is because the impurity doping causes defects in the AlGaInP mixed crystal to increase and the emission efficiency to decrease. Therefore, the laser oscillation wavelength can be shortened by doping the light emitting active layer with impurities, but the threshold current may be increased in some cases.

A particularly preferred structure of the present invention is a structure in which a quantum well layer which can obtain a gain in a multiple quantum well structure is not doped with an impurity and only a quantum barrier layer is modulated to dope the impurity. As a result, the barrier energy of the quantum barrier layer can be increased without lowering the emission efficiency of the quantum well layer that is the active region, and it can be expected that laser oscillation will occur at a shorter wavelength.

For example, the relationship between the photoluminescence peak wavelength and the GaInP quantum well layer thickness will be described with reference to FIG. A conventional undoped GaInP bulk active layer grown by metalorganic vapor phase epitaxy has a peak wavelength of 665.
nm (square mark in the figure), while an undoped multiple quantum well structure (an undoped GaInP quantum well layer with a film thickness of 3 nm and an undoped (Al _0.5 Ga _0.5 ) _0.51 film with a film thickness of 4 nm) _0.51
In _0.49 P quantum barrier layer) is 626 nm (indicated by a circle in the figure), and the quantum barrier layer is p
620nm when doped with type impurities (● in the figure)
Mark). These values are (Al _0.5 Ga _0.5 ) _0.51
The peak wavelengths when the In _0.49 P quantum barrier layer has an ordered arrangement structure and a disordered arrangement structure are calculated using band gap energies of 570 nm and 551 nm, respectively (shown by a dotted line and a solid line in the figure). It was in good agreement with the case where the film thickness was 3 nm.

Here, (Al _0.5 Ga _0.5 ) _0.51 In _0.49 P
The barrier energy when the quantum barrier layer is doped with impurities has an Al composition of 0.65 in the undoped case.
_Was equivalent to the band gap energy of the (Al _0.65 Ga _0.35 ) _0.51 In _0.49 P layer. This indicates that short wavelength laser oscillation can be achieved by the impurity modulation doping of the quantum barrier layer. In the present invention, a laser oscillation wavelength of 630 to 635 nm is obtained when the quantum barrier layer is modulated and doped with impurities, and is 5 to 6 nm more than when it is undoped.
A short oscillation wavelength was realized. When the quantum well layer is not doped with impurities, the gain is obtained by the carriers of the quantum barrier layer doped with impurities without increasing defects and decreasing the luminous efficiency. Increase and low threshold operation could be achieved.

[0019]

EXAMPLE 1 A sectional view of a semiconductor laser device according to an example of the present invention is shown in FIG. 1 and its manufacturing method will be described. The n-type Ga is formed on the n-type GaAs substrate 1 by the metal organic chemical vapor deposition method described later in detail.
As buffer layer 2 (thickness 0.5 μm, electron concentration n _D = 1
× 10 ¹⁸ cm ~ ³ ), n-type (Al _0.7 Ga _0.3 ) _0.51 In
_0.49 P optical waveguide layer 3 (thickness 1.5 μm, electron concentration n _D = 1
The light-emitting active layer 4 is epitaxially grown at × 10 ¹⁸ cm ³ ). The light emitting active layer 4 has the following structure. That is, this layer is made of undoped Ga _0.51 In with a thickness of 3 nm.
_0.49 P quantum well layer 10 and p-type impurity Zn doped (hole concentration n _A = 6 to 9 × 10 ¹⁷ cm to ³ ) with a film thickness of 4 nm
Nine layers of (Al _0.5 Ga _0.5 ) _0.51 In _0.49 P quantum barrier layers are alternately provided, and (Al _0.5 G _0.5 nm) having a film thickness of 15 nm is provided on both sides thereof.
a _0.5 ) _0.51 In _0.49 P Multiple quantum well structure provided with an optical confinement layer.

Next, p-type (Al _0.7 Ga _0.3 ) _0.51 In
_0.49 P optical waveguide layer 5 (thickness 1.2 μm, hole concentration n _A = 5
^{~7 × 10 17 cm ~ 3)} , p -type Ga _0.51 In _0.49 P buffer layer 6 (thickness 0.05 .mu.m, the hole concentration n _A = 2 × 10 ¹⁸
cm ~ ³ ) is similarly epitaxially grown.

Next, SiO _{2 is formed} by photolithography.
A mask (film thickness 0.2 μm, stripe width 5 μm) is formed, and the optical waveguide layer 5 is 0.2 μm by chemical etching.
The buffer layer 6 and the optical waveguide layer 5 are removed by etching to the point where they are left to form a ridge stripe.

Next, the n-type GaAs current constriction and light absorption layer 7 (thickness 1.0 μm, electron concentration n _D = 2 × 10 ¹⁸ cm ³ ) is selectively grown while leaving the SiO ₂ mask. Further, after p-type GaAs contact layer 8 (thickness 1 μm, electron concentration n _A = 5 × 10 ¹⁸ to 1 × 10 ¹⁹ cm ³ and high electron concentration in the upper portion) is embedded and grown, p-electrode 9 and n-electrode are formed. 10 is vapor-deposited. Furthermore, cleavage scribing is performed to cut out the element to obtain a laser element.

In the metal organic chemical vapor deposition method, trimethylaluminum is used as a raw material of Al, trimethylgallium is used as a raw material of Ga, trimethylindium is used as a raw material of In, and P is used.
Using phosphine as a raw material, the growth temperature was 700 ° C. and the pressure was 70 Torr. Dimethyl zinc was used as a raw material for modulation-doping Zn, which is a p-type impurity, in the quantum barrier layer.

The band edge energy of the quantum barrier layer in the above multiple quantum well structure is 0.42 than that of the quantum well layer.
eV is high. The laser device of this example operates at room temperature with a threshold current of 40 to 50 mA and a laser oscillation wavelength of 63.
It was 0 to 635 nm. In a device in which the quantum barrier layer is not doped with impurities, the threshold current at room temperature is 60 to 7
Since it was 0 mA and the laser oscillation wavelength was 636 to 640 nm, low threshold current operation and a shorter oscillation wavelength were realized by the present invention.

Example 2 A laser device was manufactured in the same manner as in Example 1 except that the portion of the multiple quantum well structure constituting the light emitting active layer 4 was changed as follows. That is, the multiple quantum well structure was doped with p-type impurity Zn (hole concentration n _A = 6 to 9 × 10 ¹⁷ cm to ³ )
Ga _0.51 In _0.49 P quantum well layer 10 with a thickness of 3 nm and undoped (Al _0.5 Ga _0.5 ) _0.51 In with a thickness of 4 nm
9 layers of _0.49 P quantum barrier layers were alternately provided, and (Al _0.5 Ga _0.5 ) _0.51 In _0.49 P optical confinement layers having a film thickness of 15 nm were provided on both sides thereof.

The band edge energy of the quantum barrier layer in this multiple quantum well structure is 0.33 than that of the quantum well layer.
eV is high. The laser device of this example operates at room temperature with a threshold current of 60 to 70 mA and a laser oscillation wavelength of 63.
It was 0 to 635 nm. The laser oscillation wavelength can be shortened by about 5 to 10 nm as compared with the device in which impurities are not doped.

Example 3 A laser device was manufactured in the same manner as in Example 1 except that the portion of the multiple quantum well structure constituting the light emitting active layer 4 was changed as follows. That is, a multiple quantum well structure having a film thickness of 3 nm
_{Ga 0.51 In 0.49 P (Al 0.5} Ga 0.5) of the quantum well layers 10 layers and the thickness of 4nm _0.51 In _0.49 P quantum barrier layer 9 layers are provided alternately, (Al _0.5 having a thickness of 15nm on both sides
Ga _0.5 ) _0.51 In _0.49 P All layers of the structure provided with the optical confinement layer are doped with the p-type impurity Zn (hole concentration n
_A = 6 to 9 × 10 ¹⁷ cm ³ ).

The band edge energy of the quantum barrier layer in this multiple quantum well structure is 0.36 than that of the quantum well layer.
eV is high. The laser device of this example operates at room temperature with a threshold current of 60 to 80 mA and a laser oscillation wavelength of 62.
It was 5 to 630 nm. The laser oscillation wavelength could be shortened by about 10 to 15 nm as compared with the element not doped with impurities.

In each of the above examples, each layer grown by the metal organic chemical vapor deposition method was grown by the molecular beam epitaxy method, and a laser device was similarly manufactured. In this case, using Al, Ga, and In as a starting material, the phosphine as a raw material for P, the growth temperature of 550 ℃, 10 ~ ⁵ Tor
It went with r. Each manufactured laser element showed the same effect as each laser element manufactured by the metal organic chemical vapor deposition method.

Although Zn was used as an impurity for doping the light emitting active layer in the above examples, Mg,
Similar results were obtained using Be or using n-type impurities Si and Se.

[0031]

According to the present invention, a laser device that oscillates at a shorter wavelength can be realized by modulation-doping the quantum barrier layer or the quantum well layer or by doping the entire quantum well structure with impurities. ..

Since the barrier energy of the quantum barrier layer can be increased by modulation-doping the impurities into the quantum barrier layer, the quantum level energy is increased, and a laser device that oscillates at a shorter wavelength can be realized. Furthermore, when the quantum well layer is not doped with impurities, gain is obtained by carriers in the impurity-doped quantum barrier layer without causing increase in defects and reduction in luminous efficiency, so that a laser device operating at a low threshold current can be obtained. Was obtained.

The laser device of the present invention has a temperature of 50 ° C. and a length of 3 m.
In the life test of the W constant light output operation, no remarkable deterioration was observed even after about 2000 hours.

[Brief description of drawings]

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

FIG. 2 is a diagram showing a relationship between a photoluminescence peak wavelength and a quantum well layer film thickness.

[Explanation of symbols]

 1 n-type GaAs substrate 2, 6 buffer layer 3 optical waveguide layer 4 light emitting active layer 5 optical waveguide layer 7 current constriction and light absorption layer 8 contact layer 9 p electrode 10 n electrode

Claims (22)

[Claims] 1. An (Al _y Ga _1-y ) _a In _1-a P (where y,
a is a value in the range of 0 <y ≦ 1 and 0.3 ≦ a ≦ 0.8), and the optical waveguide layer has a large forbidden band.
In a semiconductor laser device having a double heterojunction sandwiching a light emitting active layer having a smaller forbidden band on a semiconductor substrate, the light emitting active layer is (Al _x1 Ga _{1 -x1} ) _a In _{1 -a}
P (provided that x ₁ is a value in the range of 0 ≦ x ₁ <y and a is a value in the above range), and (Al _x2
Ga _1-x2 ) _a In _1-a P (where x ₂ is a value in the range of x ₁ <x ₂ <y, and a is a value in the above range) and is repeatedly provided. A semiconductor laser device having at least a multiple quantum well structure and having an impurity in the quantum barrier layer. 2. (Al _y Ga _1-y ) _a In _1-a P (where y,
a is a value in the range of 0 <y ≦ 1 and 0.3 ≦ a ≦ 0.8), and the optical waveguide layer has a large forbidden band.
In a semiconductor laser device having a double heterojunction sandwiching a light emitting active layer having a smaller forbidden band on a semiconductor substrate, the light emitting active layer is (Al _x1 Ga _{1 -x1} ) _a In _{1 -a}
P (provided that x ₁ is a value in the range of 0 ≦ x ₁ <y and a is a value in the above range), and (Al _x2
Ga _1-x2 ) _a In _1-a P (where x ₂ is a value in the range of x ₁ <x ₂ <y, and a is a value in the above range) and is repeatedly provided. A semiconductor laser device having at least a multiple quantum well structure and having impurities in the quantum well layer. 3. (Al _y Ga _1-y ) _a In _1-a P (provided that y,
a is a value in the range of 0 <y ≦ 1 and 0.3 ≦ a ≦ 0.8), and the optical waveguide layer has a large forbidden band.
In a semiconductor laser device having a double heterojunction sandwiching a light emitting active layer having a smaller forbidden band on a semiconductor substrate, the light emitting active layer is (Al _x1 Ga _{1 -x1} ) _a In _{1 -a}
P (provided that x ₁ is a value in the range of 0 ≦ x ₁ <y and a is a value in the above range), and (Al _x2
Ga _1-x2 ) _a In _1-a P (where x ₂ is a value in the range of x ₁ <x ₂ <y, and a is a value in the above range) and is repeatedly provided. A semiconductor laser device having at least a multiple quantum well structure and having impurities in the quantum well layer and the quantum barrier layer. 4. The semiconductor laser device according to claim 1, wherein the light emitting active layer further comprises (Al _x2 Ga _{1 -x2} ) _a In _{1 -a} P (provided that both sides of the multiple quantum well structure are provided. x ₂ is a value in the range of x ₁ <x ₂ <y, where x ₁ is a value in the above range and a is a value in the above range). And a semiconductor laser device. 5. The semiconductor laser device according to claim 1, wherein the quantum barrier layer has a composition (Al _{x2
Ga 1-x2) a In 1} -a X 2 in the P is, 0.4 ≦ X ₂ ≦
A semiconductor laser device having a value in the range of 0.7. 6. The semiconductor laser device according to claim 1, wherein the band edge energy of the quantum barrier layer is 0.2 eV or more higher than that of the quantum well layer. Semiconductor laser device. 7. The semiconductor laser device according to claim 1, wherein the quantum barrier layer has a thickness of 4 to
A semiconductor laser device having a range of 8 nm. 8. (Al _y Ga _1-y ) _a In _1-a P (provided that y,
a is a value in the range of 0 <y ≦ 1 and 0.3 ≦ a ≦ 0.8), and the optical waveguide layer has a large forbidden band.
In a semiconductor laser device having a double heterojunction sandwiching a light emitting active layer having a smaller forbidden band on a semiconductor substrate, the upper part of the optical waveguide layer above the light emitting active layer is stripe-shaped in the laser light emitting direction. And a current confinement and light absorption layer on both sides of the convex portion, and the light emitting active layer is
(Al _x1 Ga _1-x1 ) _a In _1-a P (where x ₁ is 0 ≦ x ₁ <
a value in the range of y, where a is the value in the above range) and (Al _x2 Ga _{1 -x2} ) _a In _1-a P (where x ₂ is x ₁ <x ₂ < a value in the range of y, a is a value in the above range), and a quantum barrier layer having at least a multiple quantum well structure repeatedly provided, and the quantum barrier layer having an impurity. And a semiconductor laser device. 9. (Al _y Ga _1-y ) _a In _1-a P (provided that y,
a is a value in the range of 0 <y ≦ 1 and 0.3 ≦ a ≦ 0.8), and the optical waveguide layer has a large forbidden band.
In a semiconductor laser device having a double heterojunction sandwiching a light emitting active layer having a smaller forbidden band on a semiconductor substrate, the upper part of the optical waveguide layer above the light emitting active layer is stripe-shaped in the laser light emitting direction. And a current confinement and light absorption layer on both sides of the convex portion, and the light emitting active layer is
(Al _x1 Ga _1-x1 ) _a In _1-a P (where x ₁ is 0 ≦ x ₁ <
a value in the range of y, where a is the value in the above range) and (Al _x2 Ga _{1 -x2} ) _a In _1-a P (where x ₂ is x ₁ <x ₂ < a value in the range of y, a is a value in the above range), and a quantum barrier layer having a multiple quantum well structure repeatedly provided, and the quantum well layer having an impurity. And a semiconductor laser device. 10. An (Al _y Ga _1-y ) _a In _1-a P (where y and a are values in the range of 0 <y ≦ 1 and 0.3 ≦ a ≦ 0.8, respectively) In a semiconductor laser device having a double heterojunction on a semiconductor substrate in which an emission active layer having a smaller forbidden band width is sandwiched by an optical waveguide layer having a larger forbidden band width, an upper portion of the optical waveguide layer above the emission active layer is provided. Is
The light emitting active layer has a stripe-shaped convex portion in the emitting direction of laser light, and a current confinement and light absorption layer on both sides of the convex portion, and the light emitting active layer is (Al _x1 Ga _{1 -x1} ) _a In _{1 -a} P (However, x ₁ is 0 ≦
x ₁ <y, where a is a value in the above range), and (Al _x2 Ga _{1 -x2} ) _a In
_1-a P (where x ₂ is a value in the range of x ₁ <x ₂ <y, and a
Is a value within the above range) and at least a multiple quantum well structure repeatedly provided with a quantum barrier layer, and the quantum well layer and the quantum barrier layer have impurities. Laser element. 11. The semiconductor laser device according to claim 8, wherein the light emitting active layer further comprises (Al _x2 Ga _{1 -x2} ) _a In _{1 -a} P (provided that both sides of the multiple quantum well structure are provided. x ₂ is a value in the range of x ₁ <x ₂ <y, where x ₁ is a value in the above range and a is a value in the above range). And a semiconductor laser device. 12. The semiconductor laser device according to claim 8, wherein the quantum barrier layer has a composition (A
X ₂ in l _x2 Ga _1-x2 ) _a In _1-a P is 0.4 ≦ X ₂
A semiconductor laser device having a value in the range of ≤0.7. 13. The semiconductor laser device according to claim 8, wherein the band edge energy of the quantum barrier layer is 0.2 eV higher than that of the quantum well layer.
A semiconductor laser device characterized by being larger than the above. 14. The semiconductor laser device according to claim 8, wherein the quantum barrier layer has a thickness of
A semiconductor laser device having a range of 4 to 8 nm. 15. A semiconductor _{substrate, (Al y Ga 1-y} ) a I
n _1-a P (where y and a are 0 <y ≦ 1 and 0.3, respectively)
≦ a ≦ 0.8) and a (Al _x1 Ga _1-x1 ) _a In _1-a P (where x ₁ is 0 ≦ x ₁ <y A value in the range, a is a value in the above range), and a (Al _x2 Ga _{1 -x2} )
_a quantum barrier layer composed of _a In _1-a P (where x ₂ is a value in the range of x ₁ <x ₂ <y and a is a value in the above range) is repeatedly provided to form a light emitting active layer. forming a multiple quantum well structure, a step of forming a light waveguide layer made of _{(Al y Ga 1-y)} a in 1-a P ( except y, a are each a value within the above range) In the method for manufacturing a semiconductor laser device having at least the above, the quantum well layer and the quantum barrier layer are formed by a metal organic chemical vapor deposition method, and the quantum barrier layer is doped with an impurity. Manufacturing method. 16. A semiconductor _{substrate, (Al y Ga 1-y} ) a I
n _1-a P (where y and a are 0 <y ≦ 1 and 0.3, respectively)
≦ a ≦ 0.8) and a (Al _x1 Ga _1-x1 ) _a In _1-a P (where x ₁ is 0 ≦ x ₁ <y A value in the range, a is a value in the above range), and (Al _x2 Ga _{1 -x2} ) _a
A quantum barrier layer made of In _1-a P (where x ₂ is a value in the range of x ₁ <x ₂ <y and a is a value in the above range) is repeatedly provided to form a light emitting active layer. forming a multiple quantum well structure, and forming a light waveguide layer made of _{(Al y Ga 1-y)} a in 1-a P ( except y, a are each a value within the above range) In the method for producing a semiconductor laser device having at least the quantum well layer and the quantum barrier layer, the quantum well layer is formed by a metal organic chemical vapor deposition method, and the quantum well layer is doped with impurities. Production method. 17. A (Al _y Ga _1-y ) _a I film on a semiconductor substrate.
n _1-a P (where y and a are 0 <y ≦ 1 and 0.3, respectively)
≦ a ≦ 0.8) and a (Al _x1 Ga _1-x1 ) _a In _1-a P (where x ₁ is 0 ≦ x ₁ <y A value in the range, a is a value in the above range), and (Al _x2 Ga _{1 -x2} ) _a
A quantum barrier layer made of In _1-a P (where x ₂ is a value in the range of x ₁ <x ₂ <y and a is a value in the above range) is repeatedly provided to form a light emitting active layer. forming a multiple quantum well structure, and forming a light waveguide layer made of _{(Al y Ga 1-y)} a in 1-a P ( except y, a are each a value within the above range) In the method for manufacturing a semiconductor laser device having at least the quantum well layer and the quantum barrier layer, the quantum well layer and the quantum barrier layer are formed by metal organic chemical vapor deposition, and the quantum well layer and the quantum barrier layer are doped with impurities. Method for manufacturing semiconductor laser device. 18. The method of manufacturing a semiconductor laser device according to claim 15, 16 or 17, wherein the metal organic chemical vapor deposition method is performed at a growth temperature in the range of 650 to 750 ° C. Production method. 19. A (Al _y Ga _1-y ) _a I film on a semiconductor substrate.
n _1-a P (where y and a are 0 <y ≦ 1 and 0.3, respectively)
≦ a ≦ 0.8) and a (Al _x1 Ga _1-x1 ) _a In _1-a P (where x ₁ is 0 ≦ x ₁ <y A value in the range, a is a value in the above range), and a (Al _x2 Ga _{1 -x2} )
_a quantum barrier layer composed of _a In _1-a P (where x ₂ is a value in the range of x ₁ <x ₂ <y and a is a value in the above range) is repeatedly provided to form a light emitting active layer. forming a multiple quantum well structure, a step of forming a light waveguide layer made of _{(Al y Ga 1-y)} a in 1-a P ( except y, a are each a value within the above range) In the method for manufacturing a semiconductor laser device having at least the above, the quantum well layer and the quantum barrier layer are formed by a molecular beam epitaxy method, and the quantum barrier layer is doped with an impurity. Method. To 20. A semiconductor _{substrate, (Al y Ga 1-y} ) a I
n _1-a P (where y and a are 0 <y ≦ 1 and 0.3, respectively)
≦ a ≦ 0.8) and a (Al _x1 Ga _1-x1 ) _a In _1-a P (where x ₁ is 0 ≦ x ₁ <y A value in the range, a is a value in the above range), and (Al _x2 Ga _{1 -x2} ) _a
A quantum barrier layer made of In _1-a P (where x ₂ is a value in the range of x ₁ <x ₂ <y and a is a value in the above range) is repeatedly provided to form a light emitting active layer. forming a multiple quantum well structure, and forming a light waveguide layer made of _{(Al y Ga 1-y)} a in 1-a P ( except y, a are each a value within the above range) In the method for manufacturing a semiconductor laser device having at least the quantum well layer and the quantum barrier layer, the quantum well layer is formed by a molecular beam epitaxy method, and the quantum well layer is doped with an impurity. .. 21. (Al _y Ga _1-y ) _a I on a semiconductor substrate
n _1-a P (where y and a are 0 <y ≦ 1 and 0.3, respectively)
≦ a ≦ 0.8) and a (Al _x1 Ga _1-x1 ) _a In _1-a P (where x ₁ is 0 ≦ x ₁ <y And a is a value in the above range), and a quantum well layer of (Al _x2 Ga _{1 -x2} ) _a I
n _1-a P (where x ₂ is a value in the range of x ₁ <x ₂ <y,
a is provided repeatedly and quantum barrier layers composed of a is) the value of the above range, forming a multiple quantum well structure forming the light-emitting active _{layer, (Al y Ga 1-y} ) a In 1-a P (Where y and a are values in the above ranges, respectively). In the method for manufacturing a semiconductor laser device, the quantum well layer and the quantum barrier layer are molecular beam epitaxy. A method of manufacturing a semiconductor laser device, which is characterized in that the quantum well layer and the quantum barrier layer are doped with impurities. 22. The method of manufacturing a semiconductor laser device according to claim 19, 20 or 21, wherein the molecular beam epitaxy method is performed at a growth temperature of 500 to 600 ° C. ..