JP3098827B2 - 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 semiconductor laser device which is suitable as a light source for an optical disk or the like and has a low noise and a low operating current value.

[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.
There is 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. GaAs current blocking layer 26 is formed. 27 is a p-type Ga
The As protective layer 28 is a p-type GaAs contact layer.

As a similar structure, there is a semiconductor laser device whose regrowth interface is close to the active layer as shown in FIG. FIG.
The semiconductor laser device shown in FIG.
On the n-type GaAs buffer layer 22.
_0.5 Al _0.5 As clad layer 23, Ga _0.85 Al _0.15 As
Active layer 24, p-type Ga _0.5 Al _0.5 As clad layer 2
5. After forming up to the n-type current block layer 26 by one crystal growth process, a stripe-shaped groove is formed by etching, and the p-type Ga _0.5 Al _0.5 As clad layer 2 is formed thereon.
9. A semiconductor laser device is manufactured by forming a p-type GaAs contact layer 28. In this structure, since the regrowth interface 25b is close to the Ga _0.85 Al _0.15 As active layer 24, there is a problem that the light distribution is affected depending on the growth conditions and the yield is lower than that of the structure of FIG. That is,
Due to diffusion of the dopant during regrowth, that is, zinc (Zn) or the like, from the regrowth interface 25b, the refractive index in the stripe increases, the spectrum tends to be in a single mode, and there is a problem that noise failure occurs. .

The operation of the conventional semiconductor laser device configured as described above will be described below. In the structure of FIG. 13, the p-type GaAs contact layer 28
Is effectively confined in the ridge 25a, and laser oscillation occurs in the Ga _0.85 Al _0.15 As active layer 24 below the ridge 25a. At this time, n-type GaAs
The refractive index of the s current block layer 26 is p-type Ga _0.5 Al _0.5
Although it is larger than the refractive index of the As clad layer 25,
Since the forbidden band width of the n-type GaAs current blocking layer 26 is smaller than the forbidden band width of the Ga _0.85 Al _0.15 As active layer 24, the n-type GaAs current blocking layer 26 becomes an absorber for laser light, The laser light is effectively confined in the ridge by absorption by the n-type GaAs current blocking layer 26. Generally, by setting the width of the lower end of the ridge 25a, that is, the stripe width to about 5 μm, a single transverse mode laser oscillation used for an optical disk or the like can be obtained.

[0005]

However, in the above-described conventional configuration, the threshold and efficiency of the semiconductor laser device 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 beam is steeply confined in the stripe due to the light absorption of the current blocking layer 26, the spectrum tends to be in a single mode. The blocking layer 26 must be separated from the Ga _0.85 Al _0.15 As active layer 24 by a certain degree or more, and there is a problem in that the leakage current in the lateral direction under the ridge 25a increases, thereby further increasing the operating current. Was.

Further, when the stripe width (the width of the lower end of the ridge 25a) is reduced, light absorption by the current blocking layer 26 is increased. Therefore, there is a restriction that the stripe width cannot be reduced to a certain extent or more. Had become.

An object of the present invention is to provide a semiconductor laser device having a multimode spectrum, low noise, and a low operating current value.

[0008]

In order to achieve this object, a semiconductor laser device according to the present invention comprises a Ga.sub.1 _-X film serving as an active layer.
Have a ridge on at least one side of the upper and lower surfaces of the al _X As layer, the thickness of the portion other than the ridge is 0.3 Mi
A first conductivity type Ga _1-Y Al _Y As layer which is less than chromium, and a reverse conductivity type Ga _1-Z Al _Z As layer along the longitudinal side surface of the ridge;
X, Y, and Z that determine the mixed crystal ratio satisfy Z>Y> X ≧ 0, and the width of a portion of the ridge closest to the active layer is 4 μm or less.

[0009]

According to this structure, Ga serving as a current blocking layer is formed.
Ga _1-x Al _x As which becomes an active layer by current injected from a stripe-shaped window of the _1-Z Al _Z As layer, that is, a ridge.
Laser oscillation occurs in the layer. Here, the stripe since the refractive index of the Ga _1-Z Al _Z As layer serving as a current blocking layer is smaller than Ga _1-Y Al _Y As layer as a stripe inner cladding layer, the laser beam by the difference in the refractive index Effectively confined within.

[0010] Further, Ga _{1 -Z} A to be a current blocking layer
l _Z bandgap of the As layer becomes an active layer Ga _1-X Al X As
Since the laser beam is not absorbed by the current blocking layer because it is much larger than the bandgap of the layer, and the light is widely distributed in the current blocking layer and also in the active layer below the current blocking layer, the spectrum is multimode. Prone.

[0011]

BRIEF DESCRIPTION OF THE DRAWINGS FIG.
I will explain while. FIG. 1 shows a half of an embodiment of the present invention.
It is sectional drawing of a conductor laser device. n-type GaAs substrate 1
An n-type GaAs buffer layer 2 is formed on
And n-type Ga_0.5Al_0.5As cladding layer (hereinafter
The lower first cladding layer) 3, Ga _0.85Al_0.15A
s active layer (hereinafter referred to as active layer) 4 and ridge 5a
P-type Ga_0.5Al_0.5As cladding layer (hereinafter referred to as second cladding layer)
(Referred to as a lad layer) 5 is formed.
In the region other than the ridge 5a serving as a current channel,
Type Ga_0.35Al_0.65As current block layer (hereinafter referred to as current block)
A lock layer 6 is formed. 7 is p-type
GaAs protective layer (hereinafter referred to as protective layer), 8 is a p-type
GaAs contact layer (hereinafter referred to as contact layer)
is there.

Here, in order to obtain a stable single transverse mode oscillation, the AlAs mixed crystal ratio of the current block layer 6 is set to the second p-type.
Is set to be higher than the AlAs mixed crystal ratio of the cladding layer 5 by 10% or more. If the AlAs mixed crystal ratio of the current blocking layer 6 is the same as that of the second cladding layer 5, the refractive index in the stripe is reduced due to the plasma effect, and the waveguide acts as an anti-guide, so that a single transverse mode oscillation occurs. Cannot be obtained. Furthermore, when the AlAs mixed crystal ratio of the current blocking layer 6 is lower than that of the p-type second cladding layer 5, the transverse mode becomes completely unstable, and the intended low operating current cannot be achieved.
In this embodiment, as shown in FIG. 1, the AlAs mixed crystal ratio of the current blocking layer 6 is changed to the AlAs of the p-type second cladding layer 5.
It is 0.15 higher than the mixed crystal ratio and 0.65.

In this structure, the p-type contact layer 8
Is injected into the ridge 5a, and laser oscillation occurs in the active layer 4 below the ridge 5a. Here, since the refractive index of the n-type current blocking layer 6 is sufficiently smaller than the refractive index of the p-type second cladding layer 5 inside the current channel, the laser light is confined in the ridge 5a by this refractive index difference, A single transverse mode laser beam is obtained.

Further, since the forbidden band width of the n-type current blocking layer 6 is larger than the forbidden band width of the active layer 4, there is no light absorption by the current blocking layer 6 seen in the conventional structure, and the waveguide is greatly reduced. Loss can be reduced, and lower operating current can be realized. Furthermore, since there is no light absorption, the laser beam spreads to the lower portion of the n-type current blocking layer 6, and the spectrum tends to be multimode, so that a low-noise laser can be easily obtained.

However, this is because the current blocking layer 6 is made of the same material GaAs as the active layer 4 and the second cladding layer 5.
Because of the use of the lAs system, the refractive index of the current blocking layer 6 may be selected to be slightly lower, about 3.2, for the refractive index of about 3.3 for the p-type second cladding layer 5. This is because the effective refractive index difference between the inside and outside of the stripe can be formed very gently as much as the conventional loss guide structure shown in FIG. For example, when ZnSe, which is a different material system, is used for the current blocking layer 6, the refractive index is about 2.4, so that the effective refractive index difference between the inside and outside of the stripe is too large, and the current blocking layer 6
Light does not spread to the lower part of the spectrum, and the spectrum is unlikely to be multimode.

FIGS. 2A and 2B show spectral characteristics and structure.
FIG. 6A is a diagram showing the relationship between the fabrication parameters, and FIG.
(B) shows the characteristics of a conventional semiconductor laser device.
3 shows characteristics of a laser device. In these figures, the horizontal axis is
Thickness d of second cladding layer 5 _p, The vertical axis is the thickness of the active layer 4
d_aIs represented. As described above, the active layer 4 is
Thickness d_a, P-type between current blocking layer 6 and active layer 4
Thickness d of the second cladding layer 5_pIs thin enough
It can be seen that mode oscillation is obtained. In particular, d_pIs thin
The leakage current to the outside of the stripe is small.
In this condition, a low-noise laser is obtained, and the operating current is further reduced.
Reduction can be realized. Specifically, in the conventional structure, d_pIs 0.
It was difficult to obtain multi-mode oscillation below 3 μm
On the other hand, in the structure of the present invention, d_pIs less than 0.2 μm
Multimode oscillation can be obtained in minutes.

FIG. 3 shows the relationship between the stripe width (width of the lower end of the ridge) and the operating current value. In the structure of the present invention, when the stripe width is reduced as in the conventional structure, there is no increase in operating current due to an increase in light absorption in the current block layer 6, and therefore the stripe width is set to a considerably smaller value than in the conventional structure. In this respect, a lower operating current can be realized. Specifically, in the conventional structure, the operating current sharply increases when the stripe width becomes 4 μm or less, whereas in the structure of the present embodiment, the operating current value is further reduced when the stripe width is reduced. When the stripe width is reduced in the structure of this embodiment, the amount of light seeping out to the current blocking layer 6 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.

FIGS. 4 (a) to 4 (d) are manufacturing process diagrams of a semiconductor laser device according to an embodiment of the present invention. First, FIG.
As shown in (a), M-type GaAs substrate 1
By an OCVD or MBE growth method, an n-type GaAs buffer layer 2 (thickness: 0.5 μm), an n-type first cladding layer 3 (thickness: 1 μm), and an active layer 4 (thickness: 0.07 μm)
m), a p-type second cladding layer 5 (thickness, 1 μm) and a p-type protection layer 7 (thickness, 0.2 μm) are sequentially formed. This protective layer 7 is necessary to protect the upper part of the ridge 5a of the p-type second cladding layer 5 through which current flows from surface oxidation. Although the conductivity type of the active layer 4 is not particularly described in FIG. 4, it may be p-type, n-type, or non-doped. Next, as shown in FIG. 4B, a dielectric film 9 such as a nitride film (silicon nitride, tungsten nitride, or the like) or silicon oxide is formed in a stripe shape, and etching is performed using the dielectric film 9 as a mask.
The ridge 5a is formed. At this time, the stripe width is 2.
The thickness d _p of the p-type second cladding layer 5 in the region other than the ridge 5a was 5 μm, and the thickness d _p was 0.15 μm. In this structure, there is no light absorption loss due to the current blocking layer 6, and the structure dimensions are all the same as the stripe width of the conventional structure (about 5 μm).
m), which is about half of the thickness d _p (0.3 μm or more) of the cladding layer 5, and a low operating current can be realized. Next, FIG.
As shown in (c), the MOC is used with the dielectric film 9 as a mask.
N-type current blocking layer 6 (thickness: 1 μm) by VD method
Are formed selectively. Here, the shape of the ridge 5a is preferably a forward mesa shape rather than an inverted mesa shape. This is because crystal growth is more difficult in the case of an inverted mesa shape than in the case of a forward mesa shape, and there is a possibility that the yield may be reduced due to a reduction in characteristics. Actually, in the case of the inverted mesa shape, the Ga selectively grown on the side surface of the ridge 5a is used.
The crystallinity of AlAs was impaired, and the threshold current of the fabricated device was about 10 mA higher than that of the forward mesa-shaped device. The characteristics shown in FIG. 5 show a forward mesa shape. The thickness of the current blocking layer 6 is required to be at least 0.4 μm because the thinning of the current blocking layer 6 causes absorption of laser light in the upper p-type contact layer 8. Next, as shown in FIG. 4D, the dielectric film 9 is removed, and a p-type contact layer 8 is formed by MOCVD or MBE growth. Finally, external electrodes (not shown) are formed on the n-type GaAs substrate 1 and the p-type contact layer 8, respectively.

FIG. 5 is a current-light output characteristic diagram of a semiconductor laser device according to one embodiment of the present invention. The characteristics of the conventional semiconductor laser device are also shown for comparison. In the semiconductor laser device of the present embodiment, since the loss of the waveguide is small,
The threshold value is low, the efficiency is high, and the operating current value is significantly reduced. Specifically, the operating current value required to emit 3 mW laser light at room temperature in a device having a resonator length of 200 μm was reduced from 50 mA to 25 mA.
Further, in the semiconductor laser device of the present embodiment, the spectrum also oscillates in multiple modes that cause self-pulsation (self-pulsation), and the RIN falls within the range of the return light rate of 0 to 10%.
A low noise characteristic with a relative noise intensity of -130 dB / Hz was obtained.

In the above embodiment, if the n-type current blocking layer 6 is grown directly on the p-type cladding layer 5 during the second crystal growth, the regrowth interface becomes a pn junction, A deep interface state may be formed, which may adversely affect the temperature dependence of laser current-to-light output characteristics. To prevent this, it is effective to form an n-type current block layer 6 after forming a p-type thin layer first in the second crystal growth. In this case, since the regrowth interface is not a pn junction, formation of a deep interface level is also eliminated.

Hereinafter, semiconductor laser devices having various cross-sectional structures will be described. FIG. 6 shows a p-type Ga _0.35 Al
FIG. 3 is a cross-sectional view of the semiconductor laser device on which a _0.65 As layer 10 is formed. In order for the p-type Ga _0.35 Al _0.65 As layer 10 to be transparent to laser light, the AlAs mixed crystal ratio is larger than the AlAs mixed crystal ratio of the active layer 4 and the leakage current in the lateral direction is reduced. Therefore, the film thickness needs to be 0.1 μm or less. In the embodiment shown in FIG. 6, p-type Ga _0.35 Al
_In order to make the refractive index the same as when there is no _0.65 As layer 10, the AlAs mixed crystal ratio of the current blocking layer 6 is made the same. The film thickness is 0.01 μm, and the film thickness is hardly affected by the current distribution. With the structure of FIG. 6, a semiconductor laser having low operating current, low noise, and excellent temperature characteristics can be realized. In the manufacturing process of the semiconductor laser device of the above embodiment, when the dielectric film 9 shown in FIG. 4 is, for example, a silicon nitride film, if an HF-based etchant is used for removal, the n-type formed by the second growth is used. The current block 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 that is harder to be etched than the current blocking layer 6 on the n-type current blocking layer 6 during the second growth. This layer is A
It also has an effect of protecting the current blocking layer 6 having a high lAs mixed crystal ratio from surface oxidation.

FIG. 7 is a sectional view of a semiconductor laser device on which an n-type GaAs layer 11 is formed. In this case, the GaAs layer
Reference numeral 11 denotes 0.5 μm, and the thickness of the current blocking layer 6 is 0.5 μm to keep flatness, which is smaller than that of the embodiment shown in FIG. The conductivity type of the GaAs layer 11 is preferably n-type in terms of current blocking. However, when the current blocking layer 6 is 0.4 μm or more, the current is sufficiently blocked. Or a high resistance layer or a multilayer of two or more layers. With the structure of FIG. 7, a stable element can be manufactured even in the manufacturing process, and a semiconductor laser device having low operating current, low noise, and excellent mass productivity can be realized.

Further, since the structure of this embodiment has a low operating current value, it is effective for increasing the output of the semiconductor laser. In particular, even when the thickness of the active layer 4 is reduced to 0.03 to 0.05 μm, as shown in FIG. A high output semiconductor laser can be realized. By actually fabricating the device with a resonator length of 350 μm for high output and coating the end face, an optical output of 100 mW or more could be realized. If such a semiconductor laser is used as a light source for an optical disk, a high-frequency superimposing circuit for realizing low noise at the time of reading is not required, and the size of the pickup can be significantly reduced. If d _p is reduced to reduce the leakage current in the horizontal direction, a single longitudinal mode is obtained.
Needless to say, higher output can be achieved.

FIG. 8 is a sectional view of a semiconductor laser device having the light guide layer 12 formed thereon. This embodiment uses p-type Ga _0.6
LOC (Lar) in which the light guide layer 12 is formed of an Al _0.4 As layer
(Ge Optical Cavity) structure, and higher output can be realized by improving the level of destruction of the end face by laser light. The AlAs mixed crystal ratio of the light guide layer 12 is A
It is sufficient that the ratio is higher than the lAs mixed crystal ratio. However, considering the temperature characteristics, it is desirable that the forbidden body width is larger than the active layer 4 by 0.3 eV or more. In FIG. 8, the AlAs mixed crystal ratio of the light guide layer 12 is 0.4. did. The thickness of the light guide layer 12 is reduced to 0.1 μm in order to reduce the leakage current in the lateral direction.
The light guide layer 12 may be provided below or on both sides of the active layer 4 instead of the upper part as shown in FIG. With this structure, a semiconductor laser with low operating current and high output can be realized.

The effects of the embodiments described above with reference to FIGS. 6, 7 and 8 are independent from each other, and an excellent semiconductor laser exhibiting each effect can be realized by combining them. An embodiment in the case of a combination will be described below.

FIG. 9 shows a p-type Ga _0.35 Al _0.65 As layer 10.
FIG. 2 is a cross-sectional view of a semiconductor laser device in which a semiconductor laser device and an n-type GaAs layer 11 are formed. That is, the structure shown in FIG.
And a semiconductor laser having a high characteristic temperature and excellent mass productivity in addition to low operating current and low noise characteristics.

FIG. 10 shows a p-type Ga _0.35 Al _0.65 As layer 1
FIG. 4 is a cross-sectional view of a semiconductor laser device in which a light guide layer and a light guide layer are formed. That is, the structure is a combination of the structure of FIG. 6 and the structure of FIG.
Even if it is not at the top of the active layer 4 but at the bottom like 0,
Or it may be on both sides. In this structure, in addition to the low operating current and low noise characteristics, the characteristic temperature is high and a higher output can be obtained.

FIG. 11 is a sectional view of a semiconductor laser device in which an n-type GaAs layer 11 and a light guide layer 12 are formed. That is, the structure is a combination of the structure of FIG. 7 and the structure of FIG. 8, and the light guide layer 12 is not under the active layer 4 as shown in FIG. You may. With this structure, it is possible to realize a semiconductor laser having higher output and excellent mass productivity in addition to low operating current and low noise characteristics.

FIG. 12 shows a p-type Ga _0.35 Al _0.65 As layer 1
FIG. 2 is a cross-sectional view of a semiconductor laser device having a 0, n-type GaAs layer 11 and a light guide layer 12 formed thereon. That is, the structure is a combination of the structure shown in FIG. 6, the structure shown in FIG. 7, and the structure shown in FIG.
Instead of the upper part of the active layer 4 as shown in FIG. With this structure, low operating current,
In addition to low noise characteristics, a semiconductor laser having a higher characteristic temperature, higher output, and excellent mass productivity can be realized.

In all the above embodiments, the substrate is n
Although only the case where an n-type current blocking layer is used is shown, a p-type current blocking layer may be used for the substrate. This is because the AlAs mixed crystal ratio of the current blocking layer 6 is high. In the case of the conventional GaAs current blocking layer 26 shown in FIG.
The diffusion length of electrons into the contact layer 28 is 2-3 μm, which is longer than the thickness of the current blocking layer 26, and it is difficult to realize a p-type current blocking layer.
In the case of a GaAlAs type layer, diffusion of electrons is suppressed, so that a p-type current blocking layer can be realized.

In all of the above embodiments, only the case where the ridge 5a is on the active layer 4, that is, the ridge 5a is on the side opposite to the n-type GaAs substrate 1 when viewed from the active layer 4, has been described. The same effect can be obtained even when it is on the same side as the GaAs substrate 1 of the mold type. Further, if the ridge 5a has a double configuration structure on both sides of the active layer 4, it goes without saying that the leakage current is further reduced and a lower operating current can be realized.

[0032]

As described above, according to the present invention, the G
a _1-X Al _X As layer possess a ridge on at least one side of the upper and lower surfaces of the film thickness of the portion other than the ridge is 0.
Provided with a one conductivity type Ga _1-Y Al _Y As layer of less than 3 microns, it includes a Ga _1-Z Al _Z As layer of opposite conductivity type along a longitudinal side of the ridge, and Al
X, Y and Z that determine the As mixed crystal ratio satisfy Z>Y> X ≧ 0 and are closest to the active layer of the ridge.
With a configuration in which the width of the portion is 4 μm or less, it is possible to realize a semiconductor laser device that has low noise and an operating current value that is significantly lower than that of the related art.

That is, since the AlAs mixed crystal ratio of the current blocking layer is set higher than the AlAs mixed crystal ratio of the cladding layer, oscillation occurs in a single transverse mode, and there is no light absorption by the current blocking layer. The loss of the wave path can be reduced, and the operating current value can be reduced.

Further, since the laser beam spreads to the current blocking layer and the active layer below the current blocking layer, multimode oscillation of the spectrum can be easily obtained as compared with the conventional case, and even if the distance between the active layer and the current blocking layer is shortened as compared with the conventional case, it is low. Noise characteristics can be obtained.

Further, since there is no light absorption by the current blocking layer, the stripe width can be made smaller than before. Therefore, the effect of reducing the leakage current and the effect of narrowing the stripe width can be used to set the dimension in the direction in which the operating current value is reduced, so that the operating current value can be further reduced as a low-noise laser for compact discs and the like. it can.

Since the reduction in the operating current value results in a reduction in the amount of heat generated in the active layer, the light output also becomes higher than in the prior art. Therefore, high output can be obtained even if the active layer is thinned. If the semiconductor laser device of the present invention having such features is used as a light source of an optical disk, it becomes possible to eliminate a high-frequency superimposing circuit for realizing low noise at the time of reading, and to realize a significant miniaturization of a pickup. .

Further, a reduction in the operating current value results in a reduction in the amount of heat generated in the laser mount portion, and a smaller and lighter heat sink can be used. As a result, a resin package can be used in place of the metal package conventionally used, and the size and cost of the pickup can be significantly reduced.

Further, since the semiconductor laser device of the present invention has a ridge structure, the regrowth interface is farther from the active layer than in the conventional structure, and high yield can be expected.
An optical pickup using such a semiconductor laser device is effective when used as a light source for an optical disk, which is required to be miniaturized.

[Brief description of the drawings]

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

FIGS. 2A and 2B are diagrams showing the relationship between spectral characteristics and structural parameters.

FIG. 3 is a diagram showing a relationship between a stripe width (width of a ridge lower end) and an operation current value.

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 current-light output characteristic diagram of a semiconductor laser device according to an embodiment of the present invention.

FIG. 6 is a sectional view of a semiconductor laser device on which a p-type Ga _0.35 Al _0.65 As layer 10 is formed.

FIG. 7 is a sectional view of a semiconductor laser device on which an n-type GaAs layer 11 is formed.

FIG. 8 is a cross-sectional view of a semiconductor laser device on which a light guide layer 12 is formed.

FIG. 9 shows a p-type Ga _0.35 Al _0.65 As layer 10 and an n-type G
Sectional view of a semiconductor laser device formed with an aAs layer 11

FIG. 10 is a sectional view of a semiconductor laser device in which a p-type Ga _0.35 Al _0.65 As layer 10 and an optical guide layer 12 are formed.

FIG. 11 is a sectional view of a semiconductor laser device in which an n-type GaAs layer 11 and a light guide layer 12 are formed.

FIG. 12 is a sectional view of a semiconductor laser device in which a p-type Ga _0.35 Al _0.65 As layer 10, an n-type GaAs layer 11, and an optical guide layer 12 are formed.

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

FIG. 14 is a cross-sectional view of a conventional semiconductor laser device in which a regrowth interface is close to an active layer.

[Explanation of symbols]

Reference Signs List 4 Active layer (Ga _1-x Al _X As layer) 5 Second cladding layer (Ga _1-Y Al _Y As layer) 5a ridge 6 Current blocking layer (Ga _1-Z Al _Z As layer)

────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Yuichi Shimizu 1006 Kazuma Kadoma, Kadoma City, Osaka Inside Matsushita Electronics Corporation (56) References JP-A-63-208292 (JP, A) JP-A-63- 265485 (JP, A) JP-A-1-151284 (JP, A) Applied Physics Letters Vol. 51, No12, p.p. 877-879 (September 21, 1987) (58) Field surveyed (Int. Cl. ⁷ , DB name) H01S 5/00-5/50 JICST file (JOIS)

Claims (11)

(57) [Claims] [Claim 1] to have a ridge on at least one side of the upper and lower surfaces of the active layer to become Ga _1-X Al _X As layer, the
Provided with a Ga _1-Y Al _Y As layer having a thickness of one conductivity type is less than 0.3 microns portions other than the ridge, of opposite conductivity type along a longitudinal side of the ridge Ga _1-Z Al _Z
X comprising an As layer and determining an AlAs mixed crystal ratio,
A semiconductor laser device wherein Y and Z satisfy Z>Y> X ≧ 0, and a width of a portion of the ridge closest to the active layer is 4 μm or less. 2. The semiconductor device according to claim ₁ , further comprising a one-conductivity-type Ga _1-Y Al _Y As layer having a ridge on at least one of an upper surface and a lower surface of the Ga _1-x Al _X As layer serving as an active layer. of opposite conductivity type along the direction of the side surface Ga _1-Z Al _Z a
s layer, and the Ga _1-Y Al _Y As layer and the Ga
_1-Z Al _Z layer thickness at one conductivity type between the As layer is formed following Ga _1-B Al B As layer 0.1 [mu] m, and AlAs
X, Y, Z and B which determine the mixed crystal ratio are such that Z>Y> X ≧ 0,
The device - semiconductor laser, wherein the B> X Der Turkey. 3. possess a ridge on at least one side of the upper and lower surfaces of the active layer to become Ga _1-X Al _X As layer, the
Provided with a Ga _1-Y Al _Y As layer having a thickness of one conductivity type is less than 0.3 microns portions other than the ridge, of opposite conductivity type along a longitudinal side of the ridge Ga _1-Z Al _Z
With the As layer and on said Ga _1-Z Al _Z As layer, the Ga _1-Z Al _Z As layer low AlAs mixed crystal ratio than, GaAlAs layer or GaA having the above at least one layer
The s layer is formed, X>Y> Z determining the AlAs mixed crystal ratio is Z>Y> X ≧ 0, and the width of the portion of the ridge closest to the active layer is 4 μm or less. A semiconductor laser device characterized by the above-mentioned. 4. A have a ridge on at least one side of the upper and lower surfaces of the active layer to become Ga _1-X Al _X As layer, the
Provided with a Ga _1-Y Al _Y As layer having a thickness of one conductivity type is less than 0.3 microns portions other than the ridge, of opposite conductivity type along a longitudinal side of the ridge Ga _1-Z Al _Z
Ga _1-x Al _x As which has an As layer and serves as the active layer
Layers are Ga _1-C Al _C As layer is formed in contact, and determines the AlAs mixed crystal ratio X, Y, Z and C Z>Y>
C> X ≧ 0 and the active layer of the ridge
A semiconductor laser device, wherein the width of the closest part is 4 μm or less. 5. A one-conductivity-type Ga _1-Y Al _Y As layer having a ridge on at least one of an upper surface and a lower surface of a Ga _1-X Al _X As layer serving as an active layer, and a longitudinal direction of the ridge. of opposite conductivity type along the direction of the side surface Ga _1-Z Al _Z a
s layer, and the Ga _1-Y Al _Y As layer and the Ga
_1-Z Al Z As between layers, the layer thickness at one conductivity type is formed following Ga _1-B Al B As layer 0.1 [mu] m, and the G
On the a _{1 -Z} Al _Z As layer, the G 1 -Z Al _Z As layer has a lower AlAs mixed crystal ratio than that of the Ga _{1 -Z} Al _Z As layer and has at least one G layer.
a, an AlAs layer or a GaAs layer is formed, and X, Y, Z and B that determine the AlAs mixed crystal ratio are Z>Y>
X ≧ 0, B> X der Turkey and semiconductor laser, characterized in - The device. 6. A one-conductivity-type Ga _1-Y Al _Y As layer having a ridge on at least one of an upper surface and a lower surface of a Ga _1-x Al _X As layer serving as an active layer, and a length of the ridge. of opposite conductivity type along the direction of the side surface Ga _1-Z Al _Z a
s layer, and the Ga _1-Y Al _Y As layer and the Ga
_1-Z Al Z As layer Ga _1-X Al X As layer thickness in one conductivity type is formed following Ga _1-B Al B As layer 0.1 [mu] m, and serving as the active layer between the the contact, Ga _1-C Al C a
X, Y, Z, B and C which determine the AlAs mixed crystal ratio are Z>Y>C> X ≧ 0 and B> X
The device - semiconductor laser which is characterized the Der Turkey. On at least one side of the upper and lower surfaces of 7. the active layer Ga _1-X Al _X As layer, have a ridge, pre
With the thickness of the portion other than the serial ridge comprises a Ga _1-Y Al _Y As layer of <br/> one conductivity type is less than 0.3 microns, along the longitudinal side of the ridge, opposite conductivity type Ga _1-Z
Al _Z As layer comprising a and the Ga _1-Z Al Z As layer wherein Ga _1-Z Al Z As layer low AlAs mixed crystal ratio than on the, GaAlAs layer or GaAs layer is formed of at least one or more layers G that is formed and is to be the active layer
In a _1-X Al X As layer in contact with Ga _1-C Al _C As layer is formed, and determines the AlAs mixed crystal ratio X, Y, Z and C Z>Y>C> X ≧ 0 With the ridge
A width of a portion closest to the active layer is 4 μm or less. 8. A one-conductivity-type Ga _1-Y Al _Y As layer having a ridge on at least one of an upper surface and a lower surface of a Ga _1-X Al _X As layer serving as an active layer, and a longitudinal direction of the ridge. of opposite conductivity type along the direction of the side surface Ga _1-Z Al _Z a
s layer, and the Ga _1-Y Al _Y As layer and the Ga
_1-Z Al Z As layer Ga _1-B Al B As layer thickness at one conductivity type the following 0.1μm between is formed, and the Ga
_1-Z Al Z As the over layer Ga _1-Z Al Z As A than layer
Ga having a low lAs mixed crystal ratio and at least one layer
AlAs layer or GaAs layer is formed, and in contact with the Ga _1-X Al X As layer to be the active layer Ga _1-C A
l _C As layer is formed, and determines the AlAs mixed crystal ratio X, Y, Z, B and C Z>Y>C> X ≧ 0, B
> Semiconductor laser, wherein the X der Turkey - The equipment. 9. The ridge is closest to the active layer.
The width of the portion is 4 μm or less.
The semiconductor laser device according to any one of claims 2, 5, 6, and 8,
Place. 10. A film thickness of a portion other than the ridge is 0.3.
Claims 2, 5, characterized in that they are smaller than microns.
The semiconductor laser device according to any one of claims 6 and 8 . 11. The ridge closest to the active layer.
Not more than 4 μm and other than the ridge
Characterized in that the thickness of the portion is less than 0.3 micron
The semiconductor laser according to any one of claims 2, 5, 6, and 8.
User device.