JPH10190126A - Semiconductor laser device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a semiconductor laser device which has a small oscillation threshold current value and a small operating current value, can prevent the deterioration of its temperature characteristic, and does not produce high noise. SOLUTION: A semiconductor laser is constituted by successively forming a first light guide layer 5 composed of InV1 (Ga1- Y1 AlY1 )1- V1 P of a first conductivity, a second light guide layer 6 composed of Ga1- Y2 AlY2 As of the first conductivity, a current blocking layer 7 which has a current passing window 7a and is composed of Ga1- ZAlZAs of a second conductivity, and a third light guide layer 8 which is composed of Ga1- Y3 AlY3 As of the first conductivity and fills up the current passing window 7a of the current blocking layer 7 on an active layer 4 composed of InV(Ga1- XAlX)1- VP, where V, V1, X, Y1, Y2, Y3, and Z are respectively set to satisfy the following relations: 0.45<=V<=0.55, 0.45<=V1<=0.55, 0<=Y2<Y3<Z<1, and 0<=X<Y1<1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a semiconductor laser device.

[0002]

2. Description of the Related Art FIG. 11 is a sectional view of a conventional semiconductor laser device (Japanese Patent Laid-Open No. 05-299767). FIG.
1, n-type GaAs is formed on a substrate 1
Layer 2 composed of n-type GaAs, n-type In
_A cladding layer 3 composed of _0.5 (Ga _0.4 Al _0.6 ) _0.5 P, an active layer 4 composed of undoped In _0.5 Ga _0.5 P, and a p-type In _0.5 (Ga _0.6 Al _0.4 ) _0.5 P composed of In _0.5 (Ga _0.6 Al _0.4 ) _0.5 P 1 of the optical guide layer 5, p-type an in _0.5 Ga _0.5 second optical guiding layer 6 composed of P, n-type in _0.5 (Ga _{0 .3} a
l _0.7 ) _0.5 P, a current blocking layer 7 having a mesa-shaped current transmission window 7 a provided for the purpose of current constriction;
Protective layer 7b composed of In _0.5 Ga _0.5 P, p-type In
_A third optical guide layer 8 made of _0.5 (Ga _0.6 Al _0.4 ) _0.5 P and a contact layer 9 made of p-type GaAs are formed in this order.

In a conventional semiconductor laser device, a current injected from a contact layer 9 is confined in a current transmission window 7 a by a current blocking layer 7. As a result, laser oscillation occurs near the portion of the active layer 4 where the active layer 4 contacts the current transmission window 7a. Here, the refractive index of the third light guide layer 8 is made higher than the refractive index of the current block layer 7 in order to confine the laser light in the current transmission window 7a by forming the semiconductor laser device into a waveguide structure. . Generally, by setting the width of the lower end of the current transmission window 7a, that is, the minimum width of the current transmissive area to about 3 μm, laser oscillation in a single transverse mode used in an optical disk device or the like can be obtained.

[0004]

However, in the conventional semiconductor laser, the current transmitting window 7 of the current blocking layer 7 is not provided.
a is oxidized. As a result, when the third light guide layer 8 is formed on this slope, the composition ratio of In, Ga, and Al constituting the third light guide layer 8 becomes a predetermined value. Will change. As a result, the lattice constant of the third light guide layer 8 changes, and lattice defects of the crystal,
Problems such as lattice misalignment and dislocation occur. this is,
This is considered to be due to the difference in the bonding distance between the elements. For this reason, a large number of non-radiative recombination centers such as lattice defects and transitions are formed in the third light guide layer 8 formed on the slope of the current transmission window 7a of the current block layer 7, and the semiconductor laser device has This causes an increase in the oscillation threshold current, an increase in the operating current value, and a deterioration in temperature characteristics.

An object of the present invention is to provide a semiconductor laser device having a small oscillation threshold current and operating current value, capable of preventing deterioration of temperature characteristics, and having low noise.

[0006]

According to a first aspect of the present invention, there is provided a semiconductor laser device having a first conductivity type on an active layer composed of In _V (Ga _1-x Al _x ) _1-VP . In _V1 (Ga _1-Y1 A
l _Y1 ) has a first light guide layer composed of _1-V1 P, and has a first conductivity type Ga _{1 -Y 2} Al _Y2 A on the first light guide layer.
s having a second optical guide layer composed of, yet the the second optical guide layer, the current block constituted by Ga _1-Z Al _Z As the second conductivity type having a current transmitting window A first conductivity type Ga _{1 -Y 3 on the} current blocking layer so as to fill the current transmission window of the current blocking layer.
Forming a third light guide layer made of Al _Y3 As;
V, V1, X, Y1, Y2, Y3, and Z are:
0.45 ≦ V ≦ 0.55, 0.45 ≦ V1 ≦ 0.55,
0 ≦ Y2 <Y3 <Z <1, 0 ≦ X <Y1 <1.

According to a second aspect of the present invention, there is provided a semiconductor laser device having a first conductivity type of In _V1 (Ga _1- ) on an active layer composed of In _V (Ga _1-x Al _x ) _{1- VP. A} first light guide layer made of _Y1 Al _Y1 ) _1-V1 P, and a first conductivity type of In _V2 (Ga _{1 -Y2} Al _Y2 ) _{1 -V2} P on the first light guide layer; And a second conductive type G having a current transmission window on the second light guide layer.
a _1-Z Al _Z As, a current blocking layer composed of Al ₁ -As, and a first conductivity type Ga _{1 -Y 3 on the} current blocking layer so as to fill a current transmission window of the current blocking layer. Al _Y3
A third light guide layer composed of As is formed, wherein V, V1, V2, X, Y1, Y2, Y3, and Z are:
0.45 ≦ V ≦ 0.55, 0.45 ≦ V1 ≦ 0.55,
0.45 ≦ V2 ≦ 0.55, 0 <Y3 <Z <1, 0 ≦ X
.Ltoreq.Y2 <Y1 <1.

According to a third aspect of the present invention, there is provided a semiconductor laser device having a first conductivity type of In _V1 (Ga _1- ) on an active layer composed of In _V (Ga _1-x Al _x ) _{1- VP. Y1} Al _Y1 ) a second light guide layer made of Ga _{1 -Y2} Al _Y2 As of the first conductivity type, having a first light guide layer made of _1-V1 P; A second conductivity type In _W (Ga ₁ -Z) having a light guide layer and further having a current transmission window on the second light guide layer;
Al _Z ) _1-WP having a current blocking layer, and a first conductivity type Ga _{1 -Y 3} is formed on the current blocking layer so as to fill a current transmission window of the current blocking layer. Al _Y3 A
s, a third light guide layer composed of
V1, W, X, Y1, Y2, Y3, and Z are 0.4
5 ≦ V ≦ 0.55, 0.45 ≦ V1 ≦ 0.55, 0.4
5 ≦ W ≦ 0.55, 0 ≦ Y2 <Y3 <1, 0 ≦ X <Y1
<Z <1.

According to a fourth aspect of the present invention, there is provided a semiconductor laser device having a first conductivity type In _V1 (Ga _1- ) on an active layer composed of In _V (Ga _1-x Al _x ) _{1- VP. A} first light guide layer made of _Y1 Al _Y1 ) _1-V1 P, and a first conductivity type of In _V2 (Ga _{1 -Y2} Al _Y2 ) _{1 -V2} P on the first light guide layer; And a second conductive type I layer having a current transmission window on the second light guide layer.
a current blocking layer composed of n _W (Ga _{1 -Z} Al _Z ) _{1 -WP; a first} current blocking layer is formed on the current blocking layer so as to fill a current transmission window of the current blocking layer. Conductive Ga
_A third light guide layer made of _1-Y3 Al _Y3 As is formed, and the V, V1, V2, W, X, Y1, Y2, Y3,
And Z are 0.45 ≦ V ≦ 0.55, 0.45 ≦ V1
≦ 0.55, 0.45 ≦ V2 ≦ 0.55, 0.45 ≦ W
≤0.55, 0≤Y3 <1, and 0≤X≤Y2 <Y1 <
Z <1.

As described above, according to the present invention, a high-quality third light guide layer free from lattice defects can be formed in a semiconductor laser device.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to FIGS.

FIG. 1 is a sectional view of a semiconductor laser device according to the present invention. In FIG. 1, a buffer layer 2 made of n-type GaAs and having a thickness of 1 μm is formed on a substrate 1 made of n-type GaAs, and n-type In _0.5 (Ga _0.3 Al _0.7 ).
Consists of _0.5 P, is constituted by a cladding layer 3, In _0.5 Ga _0.5 P having a thickness of 1.5 [mu] m, an active layer 4, p-type In _0.5 having a thickness of 35nm (Ga _0.3 Al _{0.7) 0.5}
A first optical guide layer 5 composed of P and having a thickness of 0.15 μm, composed of p-type Ga _0.8 Al _0.2 As;
a second light guide layer 6 having a thickness of m, n-type Ga _0.12
A current blocking layer 7 having a thickness of 0.7 μm; a current blocking layer 7 having a thickness of 0.7 μm; and a p-type Ga _0.22 Al _0.78 As, which is formed of Al _0.88 As. A third light guide layer 8 having a thickness of 0.5 μm;
And a contact layer 9 made of p-type GaAs and having a thickness of 3 μm. The resonator length of this semiconductor laser device is 400 μm. Hereinafter, for example, _x in In _V (Ga _1-x Al _x ) _1- VP is referred to as an Al mixed crystal ratio, and V is referred to as an In mixed crystal ratio.

In the semiconductor laser device shown in FIG.
The current injected from the contact layer 9 is confined in the current transmission window 7 a by the current blocking layer 7. As a result, of the active layers 4, the active layer 4 becomes the current transmission window 7a.
Laser oscillation occurs near the portion in contact with. The active layer 4 is n
It may be of type, p-type or undoped. In addition, in order to prevent catastrophic optical damage (COD) in which the end face of the semiconductor laser device is destroyed by its own light at the time of high output, the thickness of the active layer 4 is desirably 40 nm or less. The thickness of the active layer 4 is 35 nm.
And

In order to confine the laser beam in the current transmitting window 7a, the Al composition ratio of the current blocking layer 7 is set to the third value.
The refractive index of the third light guide layer 8 is made higher than the refractive index of the current block layer 7 by making the ratio of the Al mixed crystal of the light guide layer 8 larger than that of the current guide layer 8. In the semiconductor laser device shown in FIG. 1, in order to obtain a stable transverse mode oscillation by making the refractive index of the third light guide layer 8 sufficiently higher than the refractive index of the current blocking layer 7, the Al of the current blocking layer 7 The mixed crystal ratio is set to be 0.1 larger than the Al mixed crystal ratio of the third optical guide layer 8. When the thickness of the current blocking layer 7 is small, the third
Exudation of laser light to the light guide layer 8 of
Since the transverse mode of laser oscillation becomes unstable, it is desirable that the thickness of the current blocking layer 7 be 0.4 μm or more.

Further, by making the Al mixed crystal ratio of the first optical guide layer 5 sufficiently larger than the Al mixed crystal ratio of the active layer 4, carriers can be effectively confined. FIG.
In the semiconductor laser device shown in FIG.
By setting the l-mixed crystal ratio to 0.7, laser light in the 650 nm band can be effectively confined in the active layer 4.

In order to reduce the operating current value by not significantly affecting the light distribution in the semiconductor laser device and widening the forbidden band width by the quantum well effect so as to be transparent to laser oscillation light, It is desirable that the thickness of the second light guide layer 6 be 3 nm or less. Furthermore, since the forbidden band width of the current blocking layer 7 is larger than the forbidden band width of the active layer 4, a semiconductor laser device with no light absorption in the current blocking layer 7 and a low operating current with a small waveguide loss can be obtained.
As a result, no curvature occurs on the equiphase plane of the laser light propagating in the semiconductor laser device, and the astigmatic difference is 0.5 μm.
It was able to be reduced to the following. For example, when this semiconductor laser device is used as a light source of an optical pickup device, laser light can be focused on a smaller point on the optical disk surface, and a low-noise optical pickup characteristic can be obtained.

In order to make the refractive index of the third light guide layer 8 substantially equal to the refractive index of the first light guide layer,
The AlAs mixed crystal ratio of the light guide layer 8 was set to 0.78.

In this structure, the width of the lower end of the current transmission window 7a needs to be 3 μm or less in order to suppress the oscillation in the higher transverse mode and obtain the fundamental transverse mode oscillation. In the present embodiment, this width is 2.5 μm.

Further, from a low output of about 30 mW to 30
Stable laser light current even at high output of mW or more
In order to be confined in the area of the transmission window 7a, current transmission
The effective refractive index difference (Δn) inside and outside the window 7a region to an appropriate value
Need to adjust. Δn is 1 × 10^-2Where is more
In this case, the effect of trapping light in the area of the current transmission window 7a is reduced.
And the light density in the area of the current transmission window 7a becomes extremely large.
Become higher. At this time, the spatial
Hole burning occurs in the area of the current transmission window 7a.
Effective refractive index is increased, and the light distribution becomes more and more current transmission window
Concentrate in area 7a. As a result, the current-light output characteristics
Kink or COD that bends
And the characteristics of the semiconductor laser device are remarkably inferior.
Become On the other hand, Δn is 1 × 10^-3 When it is less than
In this case, the effect of trapping light in the area of the current transmission window 7a is reduced.
It becomes weak and the transverse mode becomes unstable. Stable single horizontal module
In order to obtain the mode oscillation, Δn should be 3 × 10^-3Above
It is desirable. Furthermore, the light distribution pattern of the guided mode
In order to prevent the deformation significance of Δn, the value of Δn is set to 5 × 10 ^-3
Above, 8 × 10^-3It is more desirable that:

The value of Δn in the semiconductor laser device of the present invention can be controlled by the Al composition ratio of the third light guide layer 8 and the Al composition ratio of the current blocking layer 7.
In the semiconductor laser device of the present embodiment, the Al composition ratio of the third light guide layer 8 is kept constant, and the A
By changing the Al composition ratio of the current blocking layer 7 within the range where the l composition ratio becomes larger than the Al composition ratio of the third optical guide layer 8, the magnitude of Δn can be easily made in the order of 10 ^-3. Can be controlled.

The magnitude of Δn can be controlled by the thickness (dp) of the first light guide layer 5. FIG.
Shows the value of Δn for p. As is clear from FIG.
As the value of dp increases, the value of Δn decreases. FIG.
In the semiconductor laser device shown in (1), the deformation of the light distribution pattern of the guided mode is prevented from a low output of about 3 mW to a high output of 30 mW or more, and the laser light is stably confined in the current transmission window 7a. Therefore, Δn is 6 × 10 ⁻³
Dp was set to 0.15 μm so that

In the semiconductor laser device according to the present invention, in order to obtain good crystallinity by lattice matching with GaAs, the mixed crystal ratio of In is particularly set to 0.5 for the semiconductor layer containing In. Is 0.45 to 0.55
If it is within the range, it can be similarly implemented.

FIGS. 3A to 3C are diagrams showing a process of manufacturing the semiconductor laser device shown in FIG.

First, as shown in FIG. 3A, a buffer layer 2, a clad layer 3, an active layer 4, a first light guide layer 5, and a second light guide layer 5 are formed on a substrate 1 by MOCVD or MBE growth. The light guide layer 6 and the current block layer 7 are sequentially formed.

Next, as shown in FIG. 3 (b), the current transmission window 7a is exposed in the air by using the photolithography technique.
Is formed by etching. As an etching method, the current block layer 7 is selectively etched using an etchant that can selectively etch a layer having a high Al mixed crystal ratio such as a hydrofluoric acid. At this time, the second guide layer 6 also functions as an etching stop layer. For this reason, variation in the etching depth is small, and a high yield can be obtained. Here, the shape of the current transmission window 7a is preferably a forward mesa shape rather than an inverted mesa shape. In the case of the inverted mesa shape, the crystal growth of the third light guide layer 8 becomes more difficult than in the case of the forward mesa shape, and the laser oscillation characteristics may be reduced. Actually, in the case of the inverted mesa shape, GaAlAs selectively grown on the side of the stripe is used.
The crystallinity of the device is impaired, and the threshold current of the manufactured device is higher than that of the device having a forward mesa shape.

Further, as shown in FIG.
The third light guide layer 8 and the contact layer 9 are formed by regrowth by VD or MBE growth. here,
Unlike the conventional semiconductor laser device in which the third light guide layer 8 is formed of an InGaAlP-based material, the semiconductor laser device of the present embodiment in which the third light guide layer 8 is formed of a GaAlAs-based material includes: Even if the composition ratio of the elements constituting the third light guide layer 8 varies, the lattice constant does not change, so that the crystal lattice defect, lattice irregularity, and dislocation are prevented. This is considered to be due to the consistency of the atomic bond distance of each element.

The second light guide layer 6 exposed in the current transmission window 7a has a small Al mixed crystal ratio. As a result, the third light guide layer 6 grown on the second light guide layer 6 is formed. Layer 8 has excellent crystallinity.

FIG. 4 is a diagram showing the magnitude of the optical output with respect to the input current of the semiconductor laser device of the present embodiment and the conventional semiconductor laser device. In FIG. 4, the conventional semiconductor laser device (line A) has a high operating current, has a non-linearity in light output characteristics when the light output is about 30 mW or more, and is saturated at about 40 mW. On the other hand, in the semiconductor laser device (line B) of the present embodiment, a maximum output of 100 mW is obtained when the input current is 132 mA. Further, the current value required to obtain an optical output of 35 mW is as extremely low as 65 mA. Further, the oscillation threshold current is smaller and the efficiency is higher than in the conventional semiconductor laser device.

In the semiconductor laser device of the present invention, since the laser light is not absorbed by the current blocking layer 7, the laser light also spreads below the current blocking layer 7, and the active layer 4 has a lower portion than the current transmitting window 7a. The other portions, that is, the portions where the transmission of current is prevented by the current blocking layer 7 act as saturable absorbers and self-pulsation occurs. As a result, the spectrum becomes multimode and a low-noise laser is obtained. As described above, in order to efficiently spread the laser light to the active layer 4, Δn may be reduced to about 3 × 10 ⁻³ , and in this case, it is understood from FIG. 2 that dp may be set to 0.3 μm. .

FIG. 5 is a diagram showing the magnitude of the light output with respect to the input current of the semiconductor laser device in which the thickness dp of the first light guide layer 5 is 0.3 μm. In a semiconductor laser device having a cavity length of 200 μm, an operating current value required to emit 3 mW laser light at room temperature is about 28 mA. The spectrum also oscillates in multiple modes causing self-pulsation, and the relative noise intensity (RIN; Relative Intensity) is within a range where the rate of return light is 10% or less.
y Noise) was obtained as low as -130 dB / Hz.

Further, it is possible to reduce Δn by increasing the thickness (da) of the active layer. When da is large, the light distribution in the direction perpendicular to the junction surface of each layer constituting the semiconductor laser device is collected on the active layer 4, and as a result, the light distribution in the active layer 4 below the current blocking layer 7 has a low refractive index The influence of the block layer 7 is reduced, and Δn is reduced.

FIG. 6 shows da and d which cause self-pulsation in the semiconductor laser device shown in FIG.
The range of the value of p is shown. In FIG. 6, self pulsation is developed in the area A, and no self pulsation is generated in the area B. Wavelength 6
In the 50 nm band, a wide range of da and dp, in particular, d
Self-pulsation is obtained even in the region of small a and dp. Here, since there is no absorption of laser light in the current blocking layer 7, the waveguide loss is reduced, and dp may be small, and leakage current to the outside of the current transmission window 7a is reduced. Furthermore, since self-pulsation can be obtained even in a state of Δn of 3 × 10 ⁻³ or more necessary for obtaining a stable fundamental transverse mode, a semiconductor laser device with low operating current and low noise can be obtained. .

The active layer 4 of the semiconductor laser device shown in FIG.
With a 5 nm thick In_0.5Ga_0.5Three layers of P
Well layer and In with a thickness of 5 nm_0.5(Ga_0.5Al
_0.5 )_0.5Triple consisting of two barrier layers of P
FIG. 7 shows a quantum well (TQW) structure.
Light output characteristics were obtained. As shown in FIG.
150m in 650nm band by adopting TQW structure
An optical output of W or more was obtained.

Next, another embodiment of the present invention will be described with reference to FIG.
This will be described with reference to FIG. FIG. 8 shows n-type GaAs.
buffer layer 2 made of n-type GaAs on a substrate 1 made of s, n-type In _0.5 (Ga _0.3 Al _0.7 ) _0.5
Clad layer formed of P 3, In _0.5 Ga _0.5 active layer composed of P 4, p-type _{In 0.5 (Ga 0.3 Al 0. 7} ) 0.5
First light guide layer 5 made of P, p-type In _0.5 G
a _0.5 P second light guide layer 6, n-type Ga
A current blocking layer 7 made of _0.12 Al _0.88 As and having a mesa-shaped current transmission window 7 a provided for the purpose of current confinement, and a third light guide layer 8 made of p-type Ga _0.22 Al _0.78 As 1 and a cross-sectional view of a semiconductor laser device in which a contact layer 9 made of p-type GaAs is sequentially formed.

FIG. 9 shows that a buffer layer 2 made of n-type GaAs and an n-type In _0.5 (Ga _0.3 Al _0.7 ) _0.5 P are formed on a substrate 1 made of n-type GaAs. Cladding layer 3, active layer 4 composed of In _0.5 Ga _0.5 P, first optical guide layer 5 composed of p-type In _0.5 (Ga _0.3 Al _0.7 ) _0.5 P, p-type Ga _0.8 Al _0.2 As second light guide layer 6, n-type an in _0.5 (Ga tHAT configured
_0.15 Al _0.85 ) _0.5 P, a current blocking layer 7 having a mesa-shaped current transmission window 7 a provided for the purpose of current confinement, and a third layer formed of p-type Ga _0.22 Al _0.78 As.
1 is a cross-sectional view of a semiconductor laser device in which a light guide layer 8 and a contact layer 9 made of p-type GaAs are sequentially formed.

FIG. 10 shows a substrate 1 made of n-type GaAs, a buffer layer 2 made of n-type GaAs, and an n-type In _0.5 (Ga _0.3 Al _0.7 ) _0.5 P. Cladding layer 3, active layer 4 composed of In _0.5 Ga _0.5 P, first optical guide layer 5 composed of p-type In _0.5 (Ga _0.3 Al _0.7 ) _0.5 P, p-type In _0.5 Ga _0.5 P second light guide layer 6, n-type an in _0.5 (Ga tHAT configured
_0.15 Al _0.85 ) _0.5 P, a current blocking layer 7 having a stripe-shaped current transmission window 7 a provided for the purpose of current confinement, and a third light guide composed of p-type Ga _0.22 Al _0.78 As. FIG. 2 shows a cross-sectional view of a semiconductor laser device in which a layer 8 and a contact layer 9 made of p-type GaAs are sequentially formed.

In each of the semiconductor laser devices of the present invention shown in FIGS. 8 to 10, the third light guide layer 8 is made of GaAlA.
Since it is composed of an s-based crystal, the lattice constant does not change even if the composition ratio of the elements constituting the third light guide layer 8 varies, as in the semiconductor laser device of FIG.
Crystal defects, lattice irregularities, and dislocations of the crystal are prevented, the oscillation threshold current and the operating current value are small, deterioration of temperature characteristics can be prevented, and a low-noise semiconductor laser device can be manufactured.

The active layer 4 of the semiconductor laser device of the present invention has a single quantum well (SQW) structure, a double quantum well (DQW) structure, a triple quantum well (TQW) structure, and a multiquantum well (MQW) structure. , GRIN structure, or separate confinement heterostructure (SC)
If a multiple quantum well structure such as the H) structure is adopted, a semiconductor laser device that achieves low operating current, high output, and low noise can be obtained.

In the semiconductor laser device of the present invention described above, the current blocking layer is formed on the second optical guide layer 5 having a small Al mixed crystal ratio, so that oxidation at the regrowth interface can be prevented. In addition, the interface resistance can be reduced.

In the above description, only the case where the n-type substrate 1 and the n-type current blocking layer 7 are used is shown. However, in the semiconductor laser device of the present invention, the Al mixed crystal of the current blocking layer 7 is used in any case. Since the ratio is high, the diffusion of electrons in the current blocking layer 7 can be suppressed. For this reason, the present invention can be similarly implemented by using a p-type semiconductor as the substrate 1 and the current blocking layer 7.

Although the semiconductor laser device in which the active layer is formed between the substrate and the current block layer has been described, the present invention can be similarly implemented when the current block layer is formed between the substrate and the active layer. is there. If the current block layer has a double confinement structure formed on both sides of the active layer, the leakage current is further reduced, and the operating current can be reduced.

Further, GaAlAs-based and InGa
Although the case where an AlP-based semiconductor material is used is shown, other material systems, for example, InP-based, InGaAsP-based, ZnSe
System, ZnCdSSe system, ZnMgSSe system, GaN system,
The present invention can be similarly implemented by using a compound semiconductor material such as an InGaN-based or AlGaN-based compound semiconductor material.

[0043]

As described above, according to the first aspect of the present invention, it is possible to prevent lattice defects occurring in the crystal constituting the third light guide layer, and to reduce the oscillation threshold current and the oscillation threshold current. It is possible to obtain a semiconductor laser device having a small operating current value, preventing deterioration in temperature characteristics, and having low noise.

According to the second aspect of the present invention, it is possible to prevent lattice defects occurring in the crystal constituting the third optical guide layer, to reduce the oscillation threshold current and the operating current value, and to reduce the temperature characteristic. The deterioration can be prevented, and a low-noise semiconductor laser device can be obtained.

According to the third aspect of the present invention, it is possible to prevent lattice defects occurring in the crystal constituting the third optical guide layer, to reduce the oscillation threshold current and the operating current value, and to reduce the temperature characteristic. The deterioration can be prevented, and a low-noise semiconductor laser device can be obtained.

According to the invention described in claim 4 of the present application, it is possible to prevent lattice defects occurring in the crystal constituting the third optical guide layer, to reduce the oscillation threshold current and the operating current value, and to reduce the temperature characteristic. The deterioration can be prevented, and a low-noise semiconductor laser device can be obtained.

[Brief description of the drawings]

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

FIG. 2 is a diagram showing a relationship between a thickness dp of a first optical guide layer and an effective refractive index difference Δn in the semiconductor laser device.

FIG. 3 is a view showing a manufacturing process of the semiconductor laser device according to the embodiment of the present invention;

FIG. 4 is an optical output characteristic diagram of the semiconductor laser device and a conventional semiconductor laser device.

FIG. 5 is a light output characteristic diagram of the semiconductor laser device according to the embodiment of the present invention.

FIG. 6 is a diagram showing ranges of dp and da giving self-pulsation in the semiconductor laser device.

FIG. 7 is a current-light output characteristic diagram of a semiconductor laser device.

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

FIG. 9 is a sectional view of a semiconductor laser device according to an embodiment of the present invention.

FIG. 10 is a sectional view of a semiconductor laser device according to an embodiment of the present invention.

FIG. 11 is a sectional view of a conventional semiconductor laser device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate 2 Buffer layer 3 Cladding layer 4 Active layer 5 1st light guide layer 6 2nd light guide layer 7 Current block layer 7a Current transmission window 7b Protective layer 8 3rd light guide layer 9 Contact layer

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor ▲ Yoshi ▼ Akio Kawa 1-1 1-1 Sachicho, Takatsuki-shi, Osaka Matsushita Electronics Corporation

Claims (6)

[Claims] [Claim 1] _{In V (Ga 1-X Al} X) 1-V on an active layer including at P, of a first conductivity type _{In V1 (Ga 1-Y1 Al} Y1)
_First light guide layer composed of _1-V1 P, G of first conductivity type
a second light guide layer made of a _1-Y2 Al _Y2 As, a current block layer having a current transmission window and made of Ga _{1 -Z} Al _Z As of the second conductivity type, and a first conductivity type Ga _1-Y3 Al
_A third light guide layer made of _Y3 As and filling the current transmission window of the current block layer is sequentially formed, and the V, V1, X, Y1, Y2, Y3, and Z are set to 0.4.
5 ≦ V ≦ 0.55, 0.45 ≦ V1 ≦ 0.55, 0 ≦ Y
A semiconductor laser device having a relationship of 2 <Y3 <Z <1, 0 ≦ X <Y1 <1. 2. An active layer composed of In _V (Ga _{1 -X} Al _X ) ₁ -VP is provided with a first conductive type of In _V1 (Ga _{1 -Y 1} Al _Y1 ).
_1-V1 P first light guide layer, first conductivity type I
Second conductivity type Ga _{1 -Z} A having a second light guide layer made of n _V2 (Ga _{1 -Y 2} Al _{Y 2} ) _{1 -V} 2 P and a current transmission window.
l _Z As with comprised current blocking layer, and formed of a first conductivity type Ga _1-Y3 Al _Y3 As, and the third light guide layer are sequentially formed to fill the current transmission window of said current blocking layer V, V1, V2, X, Y1, Y2, Y
3, and Z are 0.45 ≦ V ≦ 0.55, 0.45 ≦
V1 ≦ 0.55, 0.45 ≦ V2 ≦ 0.55, 0 <Y3
A semiconductor laser device having a relationship of <Z <1, 0 ≦ X ≦ Y2 <Y1 <1. 3. An active layer composed of In _V (Ga _1-x Al _x ) _1-VP is provided with a first conductivity type of In _V1 (Ga _1-Y1 Al _Y1 ).
_First light guide layer composed of _1-V1 P, G of first conductivity type
a _{2 -conductivity} type In _W (Ga _{1 -Z} Al _Z ) having a second light guide layer made of a _{1 -Y 2} Al _Y2 As and a current transmission window
_A current blocking layer made of _1-WP and a third light guide layer made of Ga _{1 -Y 3} Al _Y3 As of the first conductivity type and filling a current transmission window of the current blocking layer are sequentially formed. V, V1, W, X, Y1, Y2, Y3,
And Z are 0.45 ≦ V ≦ 0.55, 0.45 ≦ V1
≤0.55, 0.45≤W≤0.55, 0≤Y2 <Y3
A semiconductor laser device having a relationship of <1, 0 ≦ X <Y1 <Z <1. 4. The first conductivity type In _V1 (Ga _{1 -Y1} Al _Y1 ) is formed on an active layer composed of In _V (Ga _{1 -X} Al _X ) _{1 -VP} .
_1-V1 P first light guide layer, first conductivity type I
n _V2 (Ga _{1 -Y 2} Al _Y2 ) _{1 -V} 2 P A second light guide layer composed of P and a second conductivity type In _W (G
a _1-Z Al _Z ) A current blocking layer made of _1-WP and a first conductive type Ga _{1 -Y 3} Al _Y3 As, which fills a current transmission window of the current blocking layer. 3 light guide layers are sequentially formed, and the V, V1, V2, W, X,
Y1, Y2, Y3, and Z are 0.45 ≦ V ≦ 0.5
5, 0.45 ≦ V1 ≦ 0.55, 0.45 ≦ V2 ≦ 0.
55, 0.45 ≦ W ≦ 0.55, 0 ≦ Y3 <1, and 0
A semiconductor laser device having a relationship of ≦ X ≦ Y2 <Y1 <Z <1. 5. The semiconductor laser device according to claim 1, wherein the thickness of the second light guide layer is 3 nm or less. 6. The semiconductor laser device according to claim 1, wherein said active layer has a quantum well structure.