JP3200918B2 - Semiconductor laser device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a low-noise semiconductor laser device having a low operating current value and suitable as a light source for an optical disk or the like.

[0002]

2. Description of the Related Art A conventional semiconductor laser device will be described below. FIG. 13 is a sectional view of a conventional semiconductor laser device. An n-type GaAs buffer layer 22 is formed on an n-type gallium arsenide (GaAs) substrate 21, and an n-type gallium aluminum arsenide (Ga _0.5 Al _0.5 As) is formed thereon.
A p-type Ga _0.5 Al _0.5 As clad layer 25 having a clad layer 23, a Ga _0.85 Al _0.15 As active layer 24, and a ridge 25a is formed, and a portion other than the ridge 25a serving as a current channel is used for current confinement. n-type GaAs
A current blocking layer 26 is formed. 27 is a p-type GaAs protective layer, and 28 is a p-type GaAs contact layer.

[0003] In the structure shown in FIG.
The current injected from the s-contact layer 28 is the ridge 25a
Is effectively confined within the ridge 25a.
Laser oscillation occurs in the _0.85 Al _0.15 As active layer 24. At this time, the refractive index of the n-type GaAs current block layer 26 is p
The refractive index of the n-type GaAs current blocking layer 26 is larger than the refractive index of the n-type Ga _0.5 Al _0.5 As clad layer 25.
Since towards the forbidden band width smaller than the forbidden band width of the Ga _{0. 85} Al _0.15 As active layer 24, the n-type with respect to the laser beam Ga
The As current blocking layer 26 becomes an absorber. Therefore, the laser light is effectively confined in the ridge 25a by the absorption by the n-type GaAs current blocking layer 26.
Generally, by setting the lower end of the ridge 25a, that is, the width of the stripe to about 5 μm, a single transverse mode laser oscillation used for an optical disk or the like can be obtained.

[0004]

However, in the above-mentioned conventional structure, the threshold value and efficiency of the laser are limited by the loss of the waveguide due to the light absorption of the n-type GaAs current blocking layer 26. Since the laser light is steeply confined within the stripes due to the light absorption of the block layer 26, the spectrum is likely to be in a single mode. _0.85 Al
_There are problems such as the fact that it must be separated from the _0.15 As active layer 24 by a certain degree or more, and an increase in operating current due to an increase in lateral leakage current below the ridge 25a.

Further, when the width of the stripe is reduced, the light absorption by the current block layer 26 increases, so that there is a restriction that the width of the stripe cannot be reduced to a certain level or less, which hinders a reduction in operating current.

An object of the present invention is to solve the above-mentioned conventional problems, and an object of the present invention is to provide a semiconductor laser device having a low operating current, a multimode spectrum and low noise.

[0007]

SUMMARY OF THE INVENTION The semiconductor laser device of the present invention in order to achieve this objective is to have a ridge that is formed on at least one surface of the Ga _1-X Al _X As active layer, Li
The width of the portion of the edge closest to the active layer is 4 μm or less.
That one conductivity type Ga _1-Y Al _Y As layer and, Ga _1-Z Al of the opposite conductivity type formed along a longitudinal side of the ridge _Z As
And X, Y, and Z that determine the AlAs mixed crystal ratio have a relationship of Z>Y> X ≧ 0, and the n-type Ga _{1- Z} AlZAs layer of each of these layers Si as impurity
Is added.

[0008]

According to this structure, Ga_1-ZAl_ZAs Stra
The current flowing through the window, i.e. the ridge,
Ga_1-XAl_XLaser oscillation occurs in the As active layer.
_1-ZAl_ZThe refractive index of the As layer is Ga within the stripe._1-YA
l_YSince the laser beam is smaller than the As cladding layer,
It is effectively confined within the stripe due to the difference in the folding ratio. Sa
Ra Ga_1-ZAl_ZThe band gap of the As layer is Ga_1-XAl_XAs
Because it is much larger than the band gap of the active layer,
There is almost no light absorption by the current block layer.
Light also spreads in the active layer in the layer and below the current blocking layer.
And the spectrum becomes multimodal.

Further, n-type Ga in which laser light is guided
Since Si is added as an impurity to the AlAs layer, a loss grating in the n-type GaAlAs layer that hinders multimode oscillation is hardly formed, and sufficient multimode oscillation can be obtained.

[0010]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view of a semiconductor laser device according to one embodiment of the present invention. n-type GaAs substrate 1
An n-type GaAs buffer layer 2 is formed on
An n-type Ga _0.5 Al _0.5 As clad layer 3 and Ga
A p-type Ga _0.5 Al _0.5 As clad layer 5 having a _0.85 Al _0.15 As active layer 4 and a ridge 5 a is formed, and an n-type Ga _0.35 is formed in a region other than the ridge 5 a serving as a current channel due to current confinement. al _{0. 65} As current blocking layer 6
Are formed. 7 is a p-type GaAs protective layer, 8
Is a p-type GaAs contact layer.

Here, in order to obtain stable single transverse mode oscillation, the n-type Ga _0.35 Al _0.65 As
The p-type Ga _0.5 Al _0.5 As clad layer
10% or more higher than the AlAs mixed crystal ratio. If n
_-Type Ga _0.35 Al _0.65 As AlAs of current block layer 6
When the mixed crystal ratio is about the same as that of the p-type Ga _0.5 Al _0.5 As clad layer 5, there is a decrease in the refractive index in the stripe due to the plasma effect.
A single transverse mode oscillation cannot be obtained. N-type Ga
_When the AlAs mixed crystal ratio of the _0.35 Al _0.65 As current blocking layer 6 is lower than that of the p-type Ga _0.5 Al _0.5 As clad layer 5, the transverse mode becomes completely unstable, and the intended low operating current cannot be achieved. In the present embodiment, as shown in FIG. 1, the A of the n-type Ga _0.35 Al _0.65 As current blocking layer 6
The p-type Ga _0.5 Al _0.5 As clad layer
0.15 higher than that, and 0.65.

In such a structure, p-type GaAs
The current injected from the s-contact layer 8 is confined in the ridge 5a, and Ga _0.85 Al _0.15 A below the ridge 5a.
Laser oscillation occurs in the s active layer 4. Here, n-type Ga
_Since the refractive index of the _0.35 Al _0.65 As current blocking layer 6 is sufficiently smaller than the refractive index of the p-type Ga _0.5 Al _0.5 As clad layer 5 inside the current channel, the laser light is confined in the ridge 5 a by this difference in refractive index, and One transverse mode laser light is obtained.

Also, n-type Ga_0.35Al_0.65As current blow
The forbidden band width of the magnetic layer 6 is Ga_0.85Al _0.15As active layer 4
Because it is larger than the forbidden band width, the current
There is no light absorption by the lock layer, greatly reducing the waveguide loss
As a result, the operating current can be reduced. More light absorption
Laser beam is n-type Ga_0.35Al_{0. 65}
A broad spectrum is also provided below the As current blocking layer 6.
Easy to be in mode.

However, each n-type GaAlAs that guides light
Layer, Ga _0.35 Al _0.65 of Ga _0.5 Al _{0 .5} As cladding layer 3 and the n-type n-type in this embodiment As current blocking layer 6
The liquid phase growth method (L
In the PE method, Te is used, and in addition, metal organic chemical vapor deposition (MOC)
In the VD method), when Se is added, these impurities become G
aAlAs becomes DX center in AlAs, several mW to several tens mW
Since the saturable absorption effect becomes remarkable at the optical density of the main mode oscillating in the above, a loss grating is formed by the standing wave of the oscillating main mode. For this reason, modes other than the oscillating main mode are suppressed, and conversely, the single mode property is enhanced, and the multi-mode property, which is an advantage of this structure, is impaired.

In order to solve this problem, Si is added as an impurity to each GaAlAs layer for guiding light in a semiconductor laser having this structure. In this case, S in the GaAlAs layer
Since the activation energy of thermal capture and emission of carriers between the DX center level and the conduction band caused by i is different from that when Se or Te is used as an impurity, light absorption is saturated at a very low optical density. As a result, since the loss grating due to the oscillating main mode is hardly formed, the multi-mode property is not impaired, sufficient multi-mode oscillation can be obtained, and low noise can be easily achieved.

Next, the spectral characteristics of the semiconductor laser device having the above structure will be described. FIG. 2A is a diagram illustrating the relationship between the spectral characteristics and the structural parameters of the semiconductor laser device according to one embodiment of the present invention, and FIG. 2B is a diagram illustrating the relationship between the spectral characteristics and the structural parameters of the conventional semiconductor laser device. It is. In these figures, the horizontal axis represents the thickness (dp) of the p-type cladding layer between the current blocking layer and the active layer, and the vertical axis represents the thickness (da) of the active layer. In the present embodiment shown in FIG.
As compared with the conventional example shown in FIG. 1, even if one or both of da and dp is thin, sufficient multi-mode oscillation is obtained.
In particular, since dp may be thin, a low-noise laser can be obtained in a state where the leakage current to the outside of the stripe is small, and the operating current can be further reduced. Specifically, in the structure of the conventional example, it was difficult to obtain multimode oscillation at a dp of 0.3 μm or less, whereas in the structure of the present example, dp was 0.2 μm
Even below, sufficient multi-mode oscillation can be obtained.

Next, the relationship between the stripe width and the operating current value of the semiconductor laser device according to one embodiment of the present invention will be described with reference to FIG. The conventional example is also shown for reference. In the structure of this embodiment, unlike the conventional example, even when the stripe width is reduced, the operating current value does not increase due to the increase in light absorption by the current block layer. , And from this point, a lower operating current can be achieved. Specifically, in the structure of the conventional example, the operating current value increases when the stripe width is 4 μm or less, whereas in the structure of the present embodiment, when the stripe width is reduced, the operating current value increases in proportion to the stripe width. Reduce. Further, when the stripe width is reduced in the structure of the present embodiment, the exudation of light into the current block layer is relatively increased as compared with the light inside the stripe, so that the multi-modality of the spectrum is further enhanced. That is, the noise can be reduced by reducing the stripe width.

Next, a method for manufacturing the semiconductor laser device of the present invention will be described. FIG. 4 is a manufacturing process diagram of the semiconductor laser device. First, as shown in FIG.
An n-type GaAs buffer layer 2 (thickness: 0.5 μm) is formed on an aAs substrate 1 by MOCVD or MBE growth.
m), n-type Ga _0.5 Al _0.5 As clad layer 3 (thickness,
1 μm), Ga _0.85 Al _0.15 As active layer 4 (thickness, 0.1 μm).
07 μm), p-type Ga _0.5 Al _0.5 As clad layer 5
(Thickness: 1 μm) and a p-type GaAs protective layer 7 (thickness: 0.2 μm). This protective layer 7 is necessary for preventing the surface oxidation of the p-type Ga _0.5 Al _0.5 As clad layer 5 through which current flows. Although the conductivity type of the active layer 4 is not particularly described, whether it is p-type or n-type,
It may be undoped.

Next, as shown in FIG.
Film (silicon nitride, tungsten nitride) or
A dielectric film 9 such as a silicon oxide film is formed.
9 is used as a mask to form a ridge 5a.
I do. At this time, the lower end of the ridge 5a having the stripe width
The width is 2.5 μm, and the p-type Ga
_0.5Al_0.5The thickness (dp) of the As cladding layer 5 is 0.1
The thickness was 5 μm.

Next, as shown in FIG.
N-type Ga _0.35 Al by MOCVD using
_{The 0.65} As current blocking layer 6 (thickness: 1 μm) is selectively formed. If the n-type Ga _0.35 Al _0.65 As current blocking layer 6 is thin, laser light is absorbed in the p-type GaAs contact layer 8 thereover.
A thickness of μm is required. All of the above n-type GaAs
Si is added as an impurity to the lAs layer.

Next, as shown in FIG.
Is removed, and a p-type GaAs contact layer 8 is formed by MOCVD or MBE growth. Finally, n-type Ga
Electrodes are formed on the As substrate 1 side and the p-type GaAs contact layer 8 side, respectively, to complete a semiconductor laser device.

In the semiconductor laser of this embodiment, the operating current required to emit 3 mW laser light at room temperature is as low as 25 mA in a device having a cavity length of 200 μm, and the spectrum is self-pulsating (self-pulsation). )
Oscillated in multiple modes sufficient to cause The actual noise characteristic is -135 dB / Hz within the range of the return light rate of 0 to 10%.
The following RIN values were obtained, realizing low noise.

In the manufacturing process shown in FIG. 4, when the n-type Ga _0.35 Al _0.65 As current blocking layer 6 is grown directly on the p-type Ga _0.5 Al _0.5 As clad layer 5 during the second crystal growth. The regrowth interface becomes a pn junction to form a deep interface state, which may adversely affect the temperature dependence of the current-light output characteristics of the laser. To prevent this, the second Ga _{0. 35} Al _0.65 n-type after forming the thin p-type layer on the first time of crystal growth of As current blocking layer 6
It is effective to form In this case, the regrowth interface is p-
Since it is no longer an n-junction, no deep interface state is formed.

Hereinafter, another embodiment of the present invention will be described with reference to FIGS.
This will be described with reference to FIG. FIG. 5 is a sectional view of a semiconductor laser device according to a second embodiment of the present invention, showing an example in which a p-type Ga _0.35 Al _0.65 As current blocking layer 6 is formed at the time of the second crystal growth. In this case, the n-type Ga _0.35 Al _0.65 As current blocking layer 6 is made of p-type Ga _0.35 Al _0.65 As.
_{It is formed on the 0.5} Al _0.5 As clad layer 5 via an n-type Ga _0.35 Al _0.65 As layer 17 to which Si is added. The n-type Ga _0.35 Al _0.65 As current blocking layer 6
Must be transparent to laser light,
The mixed crystal ratio of As is Ga _0.85 Al _0.15 As
The film thickness needs to be 0.1 μm or less in order to be larger than the s mixed crystal ratio and to reduce the leakage current in the lateral direction. In this embodiment, in order to make the refractive index the same as when there is no p-type layer, the AlAs of the n-type Ga _0.35 Al _0.65 As layer 17 is used.
Ga _0.35 Al _0.65 As current blocking layer 6 with n-type mixed crystal ratio
And the same. The thickness of the n-type Ga _0.35 Al _0.65 As layer 17 is 0.01 μm, which is a thickness that hardly affects the current distribution. With the structure of FIG. 5, a semiconductor laser having low operating current, low noise, and excellent temperature characteristics can be obtained.

When a semiconductor laser device having the above-described effect is fabricated on a p-type GaAs substrate, the crystal is grown by reversing the p-type and n-type conductivity types in the above embodiment. However, in this case, the n-type Ga _0.35 Al _0.65 As layer 17 in FIG. 5 becomes p-type. Further, by adding Si as an impurity to the p-type thin layer at this time, the multi-mode property is not impaired in this layer.

FIG. 6 shows a semiconductor device according to a third embodiment of the present invention.
FIG. 2 is a cross-sectional view of a body laser device, on a p-type GaAs substrate.
An example of the formation is shown. As shown in FIG.
P-type GaAs buffer layer 1 on a GaAs substrate 10
1, p-type Ga_0.5Al_0.5As clad layer 12, Ga
_0.85Al_0.15As active layer 4, ridge 13 doped with Si
n-type Ga having a_0.5Al_0.5As clad layer 13,
p-type Ga_0.35Al_0.65As current blocking layer 14
N-type GaAs protective layer 15 on
A GaAs contact layer 16 is formed. In addition, p-type
Ga_0.35Al_0.65The As current blocking layer 14 is doped with Si.
N-type Ga added_0.5Al_0.5On the As cladding layer 13
N-type Ga doped with Si_0.35Al_0.65Via the As layer 17
It is formed. Each layer in the structure of this embodiment is
The structure shown in FIG. 5 is inverted from that of the structure shown in FIG.
It has the same effect as in the case. In addition, this n-type Ga
_0.35Al _0.65Si is added to the As layer 17 as an impurity.
Multi-modality is lost in this layer
And low operating current, low noise and excellent temperature characteristics
A body laser can be obtained.

In the manufacturing process shown in FIG.
When an aAs substrate is used, an HF-based etchant is used to remove the silicon nitride film constituting the dielectric film 9, but at this time, the n-type Ga _0.35 Al formed by the second growth is used.
_{The 0.65} As current blocking layer 6 may be etched at the same time. In order to prevent this, it is effective to introduce a layer having a low AlAs mixed crystal ratio for etching prevention on the n-type Ga _0.35 Al _0.65 As current blocking layer 6 during the second growth. This layer high AlAs mixed crystal ratio Ga _0.35 Al _0.65 A
It also has the effect of protecting the s current block layer 6 from surface oxidation. Further, by adding Si as an impurity to this layer, the multi-mode property is not impaired in this layer.

FIG. 7 is a sectional view of a semiconductor laser device according to a fourth embodiment of the present invention, in which an n-type GaAlAs layer 1 is formed.
8 is introduced by 0.5 μm. In FIG. 7, the thickness of the n-type Ga _0.35 Al _0.65 As current blocking layer 6 is 0.5 μm, which is smaller than that of the embodiment shown in FIG. 1, in order to maintain flatness. The introduced GaAlAs layer 18
The conductivity type of the layer is preferably the n-type in terms of blocking current, and noise can be reduced without impairing the multi-mode property by adding Si as an impurity. N-type GaAlAs
The layer 18 may be a multilayer of two or more layers. With the structure in FIG. 7, a semiconductor laser device having low operating current, low noise, and excellent mass productivity can be obtained.

The structure in the embodiment described above has a low operating current value and can be operated in multiple modes as compared with the conventional one, so that a low-noise and high-output semiconductor laser can be realized. As a high-power semiconductor laser device, an optical output of 100 mW or more can be obtained by coating the end face with a cavity length of 350 μm, and multimode oscillation can be achieved at low output of several mW. Was. By using such a semiconductor laser device as a light source of an optical disk, a high-frequency superimposing circuit for reducing noise at the time of reading is not required, and the pickup can be significantly reduced in size.

FIG. 8 is a sectional view of a semiconductor laser device according to a fifth embodiment of the present invention, and shows a p-type Ga _0.6 Al _0.4 A
The example of the LOC structure having the s light guide layer 19 has been described. In the structure shown in FIG. 8, the level of destruction by light on the end face is improved, so that higher output can be achieved. p-type Ga _0.6
The AlAs mixed crystal ratio of the Al _0.4 As light guide layer 19 is Ga _0.
It is sufficient that the band gap is higher than the AlAs mixed crystal ratio of the 85Al _0.15 As active layer 4. However, considering the temperature characteristics, the forbidden band width is Ga _0.85
Desirably 0.3 eV or more larger than the Al _0.15 As active layer 4. In this embodiment, the p-type Ga _0.6 Al _0.4 As light guide layer 19 has an AlAs mixed crystal ratio of 0.4, and its layer thickness is in the lateral direction. Is reduced to 0.1 μm in order to reduce the leakage current. When the light guide layer is n-type, the addition of Si as an impurity prevents the multi-mode property from being impaired in this layer. The light guide layer is shown in FIG.
However, it may be provided not on the lower portion of the active layer but on the upper portion or both sides. According to the structure of this embodiment, a semiconductor laser device having a low operating current, a high output, and a low noise can be obtained.

The effects of the structure shown in FIG. 5, FIG. 6, the structure shown in FIG. 7, and the structure shown in FIG. 8 are independent of each other. By combining these structures, an excellent semiconductor laser device having both effects is obtained. Can be obtained. An embodiment in the case of a combination will be described below.

FIG. 9 is a sectional view of a semiconductor laser device according to a sixth embodiment of the present invention, and shows an example in which the structure of FIG. 5 and the structure of FIG. 7 are combined. In this case, it is possible to obtain a semiconductor laser device that has high characteristic temperature in addition to low operating current and low noise characteristics and is excellent in mass productivity.

FIG. 10 is a sectional view of a semiconductor laser device according to a seventh embodiment of the present invention, showing an example in which the structure of FIG. 5 and the structure of FIG. 8 are combined. Light guide layer 1
9 may not be on the upper part of the active layer 4 but may be on the lower part or on both sides. In this case, a high-output semiconductor laser device having a high characteristic temperature in addition to the low operating current and low noise characteristics can be obtained.

FIG. 11 is a sectional view of a semiconductor laser device according to an eighth embodiment of the present invention, and shows an example in which the structure of FIG. 7 and the structure of FIG. 8 are combined. Light guide layer 1
9 may not be on the upper part of the active layer 4 but may be on the lower part or on both sides. In this case, in addition to the low operating current and low noise characteristics, a semiconductor laser device having higher output and excellent mass productivity can be obtained.

FIG. 12 is a sectional view of a semiconductor laser device according to a ninth embodiment of the present invention, and shows an example in which the structure of FIG. 5, the structure of FIG. 7, and the structure of FIG. 8 are combined.
The light guide layer 19 may be provided not on the upper portion of the active layer 4 but on the lower portion or on both sides. In this case, it is possible to obtain a semiconductor laser device having a high characteristic temperature in addition to the low operating current and low noise characteristics, a higher output, and excellent mass productivity.

In each of the above embodiments, the substrate is n-type,
Although either of p-type and n-type may be used, the current blocking layer is n-type when the substrate is n-type, and the cladding layer on which the ridge is formed is n-type when the substrate is p-type. Further, in these structures, n-type Ga
By adding Si as an impurity to the AlAs layer,
The noise can be reduced without impairing the multimodality in that layer.

[0037]

As described above, according to the present invention, Ga _1-x Al _x A
a Ga _1-Y Al _Y As layer of the one conductivity type having a ridge formed on at least one surface of the s active layer, of the opposite conductivity type formed along a longitudinal side of the ridge Ga _1-Z Al _Z A
X, Y and Z for determining the AlAs mixed crystal ratio
Is a relation of Z>Y> X ≧ 0, and of these layers, an n-type GaAlAs layer is doped with Si as an impurity, whereby an excellent semiconductor laser having a low operating current value and low noise is obtained. The device can be realized.

Further, according to the present invention, A of the current blocking layer
Since the lAs mixed crystal ratio is set higher than the AlAs mixed crystal ratio of the cladding layer, it oscillates in a single transverse mode, and there is almost no light absorption by the current block layer of the laser light, and the loss of the waveguide is greatly reduced. As a result, the operating current value can be reduced.

Further, according to the present invention, since light spreads in the current blocking layer and the active layer therebelow, multimode oscillation of the spectrum is easily obtained, so that the distance between the active layer and the current blocking layer can be made shorter than before. A low-noise semiconductor laser device that is excellent in multi-mode characteristics and hardly forms a loss grating due to the main mode oscillating by adding Si as an impurity to each n-type GaAlAs layer that guides light. Is obtained.

Further, according to the present invention, the stripe width can be made narrower than in the prior art because there is almost no light absorption by the current blocking layer. As a result, the synergistic effect of the effect of reducing the leakage current and the effect of narrowing the stripe width can be obtained. Thus, the dimensions can be set in the direction of lowering the operating current value, and the operating current value can be further reduced as a low-noise laser for a compact disk or the like.

Further, according to the present invention, the reduction in operating current value leads to a reduction in the amount of heat generated in the active layer, so that the optical output also increases as compared with the prior art. Multi-mode oscillation is possible, and if such a semiconductor laser device is used as a light source of an optical disk, a high-frequency superimposing circuit for reducing noise at the time of reading is not required, and the optical pickup can be significantly reduced in size.

[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. 2A is a diagram illustrating a relationship between a spectrum characteristic and a structure parameter of a semiconductor laser device according to an embodiment of the present invention; FIG. 2B is a diagram illustrating a relationship between a spectrum characteristic and a structure parameter of a conventional semiconductor laser device;

FIG. 3 is a diagram showing a relationship between a stripe width and an operating current value of the semiconductor laser device according to one embodiment of the present invention.

FIGS. 4A to 4D are manufacturing process diagrams of a semiconductor laser device according to an embodiment of the present invention.

FIG. 5 is a sectional view of a semiconductor laser device according to a second embodiment of the present invention.

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

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

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

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

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

FIG. 11 is a sectional view of a semiconductor laser device according to an eighth embodiment of the present invention.

FIG. 12 is a sectional view of a semiconductor laser device according to a ninth embodiment of the present invention.

FIG. 13 is a sectional view of a conventional semiconductor laser device.

[Explanation of symbols]

4 Ga _0.85 Al _0.15 As active layer (Ga _1-x Al _X As active layer) 5 p-type Ga _0.5 Al _0.5 As clad layer (one conductivity type Ga _1-Y Al _Y As layer) 5 a ridge 6 n-type Ga _0.35 Al _0.65 As current blocking layer (Ga _1-Z Al _Z As layer of reverse conductivity type)

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-63-208292 (JP, A) JP-A-2-113586 (JP, A) JP-A-3-238886 (JP, A) JP-A-1- 151284 (JP, A) IEICE Technical Report (ED 91-116) Vol. 31, No. 321 pp. 1-5 (58) Fields surveyed (Int. Cl. ⁷ , DB name) H01S 5/00-5/50 JICST file (JOIS)

Claims (9)

(57) [Claims] [Claim 1] have a ridge that is formed on at least one surface of the Ga _1-X Al _X As active layer, the active of the ridge
A one-conductivity-type Ga _1-Y Al _Y As layer in which the width of the portion closest to the conductive layer is 4 μm or less, and a reverse-conductivity-type Ga _1-Z Al _Z formed along the longitudinal side surface of the ridge. And an As layer, wherein Z> X, Y and Z determining the AlAs mixed crystal ratio.
It has a relationship of Y> X ≧ 0, and is Ga ₁ -Z A of the opposite conductivity type.
The semiconductor laser device characterized by Si as an impurity is added to l _Z As layer. 2. A one-conductivity-type Ga _1-Y having a ridge formed on at least one surface of a Ga _1-x Al _x As active layer.
An Al _Y As layer, a reverse conductivity type Ga ₁ -Z Al _Z As layer formed along the longitudinal side surface of the ridge,
_One- conductivity-type Ga _{1 -B} Al _B having a thickness of 0.1 μm or less formed between the _1-Y Al _Y As layer and the Ga _{1 -Z} Al _Z As layer.
An As layer, and a relation of Z>Y> X ≧ 0 and B> X among X, Y, Z and B for determining the AlAs mixed crystal ratio,
A semiconductor laser device, wherein Si is added as an impurity to the n-type GaAlAs layer in each of the layers. 3. A one-conductivity-type Ga _1-Y having a ridge formed on at least one surface of a Ga _1-x Al _x As active layer.
An Al _Y As layer, a reverse conductivity type Ga ₁ -Z Al _Z As layer formed along the longitudinal side surface of the ridge,
_1-Z Al _Z As formed on said layer Ga _1-Z than Al _Z As layer and a GaAlAs layer or GaAs layer AlAs mixed crystal ratio is formed of at least one layer lower, AlAs
GaAlA which has a relation of Z>Y> X ≧ 0 among X, Y and Z which determine the mixed crystal ratio, and is an n-type GaAlA
A semiconductor laser device, wherein Si is added as an impurity to an s layer. 4. The ridge formed on at least one surface of the Ga _1-x Al _x As active layer, which is closest to the active layer.
A one-conductivity-type Ga _1-Y Al _Y As layer having a ridge with a width of 4 μm or less, and a reverse-conductivity-type Ga _1-Z Al _Z As layer formed along the longitudinal side surface of the ridge When the Ga _1-X Al X As active layer formed in contact with the Ga _1-C
A al _C As layer, determines the AlAs mixed crystal ratio X,
Y, semiconductor, characterized in having a Z>Y>C> X ≧ 0 the relationship between Z and C, the Si as an impurity is added to the Ga _1-Z Al _Z As layer of the opposite conductivity type Laser device. 5. A one-conductivity-type Ga _1-Y having a ridge formed on at least one surface of a Ga _1-x Al _x As active layer.
An Al _Y As layer, a reverse conductivity type Ga ₁ -Z Al _Z As layer formed along the longitudinal side surface of the ridge,
_One- conductivity-type Ga _{1 -B} Al _B having a thickness of 0.1 μm or less formed between the _1-Y Al _Y As layer and the Ga _{1 -Z} Al _Z As layer.
Comprising As layers, and the Ga _1-Z Al _Z As formed on said layer Ga _1-Z Al _Z As layer made of at least one layer low AlAs mixed crystal ratio than the GaAlAs layer or GaAs layer, X, Y, Z and B that determine the AlAs mixed crystal ratio
Have the relationship of Z>Y> X ≧ 0 and B> X, and the n-type GaAlAs layer in each of the layers has S as an impurity.
A semiconductor laser device to which i is added. 6. _One conductivity type Ga _{1 -Y} having a ridge formed on at least one surface of a Ga _{1 -X} Al _X As active layer.
An Al _Y As layer, a reverse conductivity type Ga ₁ -Z Al _Z As layer formed along the longitudinal side surface of the ridge,
_One- conductivity-type Ga _{1 -B} Al _B having a thickness of 0.1 μm or less formed between the _1-Y Al _Y As layer and the Ga _{1 -Z} Al _Z As layer.
As layers, the Ga _1-X Al X As active layer and a Ga _1-C Al _C As layer formed in contact, X determine the AlAs mixed crystal ratio, Y, Z, between B and C Z>Y>C> X ≧
A semiconductor laser device having a relationship of 0, B> X, and wherein Si is added as an impurity to an n-type GaAlAs layer in each of the layers. 7. A one-conductivity-type Ga _1-Y having a ridge formed on at least one surface of a Ga _1-x Al _x As active layer.
An Al _Y As layer, a reverse conductivity type Ga ₁ -Z Al _Z As layer formed along the longitudinal side surface of the ridge,
_1-Z Al _Z As formed on said layer Ga _1-Z Al Z As layer and GaAlAs layer or GaAs layer AlAs mixed crystal ratio is formed of at least one layer lower than the Ga _1-X A
l _X As active layer and a Ga _1-C Al C As layer formed in contact, determine the AlAs mixed crystal ratio X, Y, Z and B
Wherein Z>Y>C> X ≧ 0 and Si is added as an impurity to the n-type GaAlAs layer of each of the layers. 8. A one-conductivity-type Ga _1-Y having a ridge formed on at least one surface of a Ga _1-x Al _x As active layer.
An Al _Y As layer, a reverse conductivity type Ga ₁ -Z Al _Z As layer formed along the longitudinal side surface of the ridge,
_One- conductivity-type Ga _{1 -B} Al _B having a thickness of 0.1 μm or less formed between the _1-Y Al _Y As layer and the Ga _{1 -Z} Al _Z As layer.
As layers, and a GaAlAs layer or GaAs layer composed of the Ga _1-Z Al _Z As formed on said layer Ga _1-Z Al _Z As at least one layer of low AlAs mixed crystal ratio than layer, the Ga G formed in contact with the _1-x Al _x As active layer
a _1-C Al _C As layer, and Z>Y>C> X ≧ 0, X>Y>C> X ≧ 0 between X, Y, Z, B and C which determine the AlAs mixed crystal ratio
> X, and n-type Ga
A semiconductor laser device, wherein Si is added as an impurity to an AlAs layer. 9. The method according to claim 1, wherein the Ga _1-X Al _X As active layer and the Ga
_1-Z Al _Z The distance from the As layer must be 0.3 μm or less.
5. The semiconductor laser device according to claim 1, wherein:
Place.