JP2842465B2 - Semiconductor laser device and method of manufacturing the same - 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 suitable for use as a light source for an optical disk or the like and having a low operating current and a low noise having a visible wavelength.

[0002]

2. Description of the Related Art A conventional semiconductor laser device will be described below.

FIG. 15 is a sectional view of a conventional semiconductor laser device. (JP-A-62-73687) An n-type gallium aluminum arsenide (Ga _0.65 Al _0.35 As) cladding layer 22 on an n-type gallium arsenide (GaAs) substrate 21,
There is an active layer 23, a p-type Ga _0.75 Al _0.25 As first cladding layer 24, and an n-type Ga _0.51 Al _0.49 As for current confinement in a portion other than the window 25a serving as a current channel.
A current block layer 25 is formed. 26 is a p-type Ga _0.75 Al _0.25 As second cladding layer formed by regrowth, and 27 is a p-type GaAs contact layer.

In the structure shown in FIG. 15, the current injected from the p-type GaAs contact layer 27 is effectively confined in the window 25a, and the GaAs active layer 23 below the window 25a.
Causes laser oscillation. At this time, n-type Ga _0.51 Al
_0.49 As The refractive index of the current blocking layer 25 is p-type Ga
The refractive index is smaller than the refractive index of the _0.75 Al _0.25 As second clad layer 26, and the laser light is also effectively confined in the window 25a. Further, the forbidden band width of the n-type Ga _0.51 Al _0.49 As current blocking layer 25 is sufficiently larger than the forbidden band width of the GaAs active layer 23, so that the n-type G
a _0.51 Al _0.49 As current blocking layer 25 becomes transparent,
A low operating current semiconductor laser with small internal loss is obtained.

[0005]

Since it is difficult to regrow the semiconductor laser having the above-described conventional structure, the p-type Ga _0.75
There was a problem that the AlAs mixed crystal ratio of the Al _0.25 As first cladding layer 22 could not be increased, and the temperature characteristics were poor. Therefore, in particular, there is a problem that a laser in the visible region of the 780 nm band cannot be easily realized. That is, when regrowth is performed on GaAlAs having a high AlAs mixed crystal ratio, the crystallinity of the regrowth interface deteriorates due to the problem of surface oxidation, and a defect occurs in the current-voltage characteristics. Al
This is because it is necessary to lower the As mixed crystal ratio to some extent.
For easy fabrication, it is necessary to make the AlAs mixed crystal ratio 0.3 or less. However, since the confinement of carriers in the active layer is limited, a laser having excellent temperature characteristics cannot be obtained. In particular, in this case, laser oscillation in the visible region that requires an AlAs mixed crystal ratio of about 0.5 is very difficult. In addition, since a time-controlled etchant is used in etching the stripe portion, it is difficult to stop the etching in the thin first cladding layer, which has led to a reduction in yield.

Further, it is also difficult to realize low noise characteristics required for application to an optical disk or the like. This is because the AlAs mixed crystal ratio of the first cladding layer 22 needs to be set low for the above-mentioned reason, so that the effective refractive index difference in the horizontal direction at the junction increases and the single-mode property of the spectrum increases.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has improved a temperature characteristic, a noise characteristic and a manufacturing method, and has a low operating current value and a low noise semiconductor laser device which can be easily manufactured even in a visible region. The purpose is to provide.

[0008]

In order to achieve this object, a semiconductor laser device according to the present invention comprises a _first conductive type Ga ₁ -Y ₁ Al _Y1 As first light on at least one side of a main surface of an active layer. guiding layer having a low Al composition which acts as an etching stop layer Ga _1-Y2 Al _Y2 as Alternatively, In _{0. 5} Ga _0.5
A second light guide layer composed of P, In _0.5 (GaAl) _0.5 P, and InGaAsP was sequentially provided, and the second light guide layer was selectively etched in a stripe shape with the opposite conductivity type to the second light guide layer. Ga _1-Z Al _Z as layer having a window and is formed on the stripe-shaped window is made includes a Ga _1-Y3 Al _Y3 as layer of the same conductivity type as the light guide layer, AlAs mixed crystal The ratio, Y1, Y2, Y3, and Z, has a configuration that establishes the relationship of Z>Y3> Y2, Y1> Y2.

[0009]

With this configuration, the confinement of carriers in the active layer is determined by the _{Ga1 -Y1AlY1As} first light guide layer having a high AlAs mixed crystal ratio, and regrowth is performed on the second light guide layer having a low Al composition. Therefore, regrowth can be easily performed. In addition, a striped window can be formed with good control by selective etching. Further, the first light guide layer AlAs
By increasing the mixed crystal ratio, the effective refractive index difference in the horizontal direction at the junction can be reduced, and the spectrum can be made multimode.

[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 an embodiment of the present invention. An n-type GaAs buffer layer 2 is formed on an n-type GaAs substrate 1, and an n-type Ga _0.5 Al _0.5 As clad layer 3 and a Ga
_0.85 Al _0.15 As active layer 4, p-type Ga _0.5 Al _0.5 As
A first light guide layer 5 and a p-type Ga _0.8 Al _0.2 As second light guide layer 6 are formed, and n-type Ga _0.4 A is formed in a region other than the window 7a serving as a current channel for current confinement.
An l _0.6 As current blocking layer 7 is formed. 8 is G
a _0.8 Al _0.2 As protective layer, 9 is p-type Ga _0.5 Al _0.5 A
The s cladding layer 10 is a p-type GaAs contact layer.

Here, in order to obtain a stable single transverse mode oscillation, the AlAs mixed crystal ratio of the current blocking layer 7 is changed to a p-type Ga
_{It is} set higher than the AlAs mixed crystal ratio of the _0.5 Al _0.5 As cladding layer 9. If the AlAs mixed crystal ratio of the current blocking layer 7 is the same as that of the cladding layer 9, the refractive index in the stripe is lowered due to the plasma effect, and the stripe becomes an anti-guide waveguide, and a single transverse mode oscillation is obtained. Absent. That is, the AlAs mixed crystal ratio of the current blocking layer 7 is p-type Ga.
_When it is lower than the _0.5 Al _0.5 As cladding layer 9, the transverse mode becomes completely unstable. In the present embodiment shown in FIG. 1, the AlAs mixed crystal ratio of the current blocking layer 7 is changed to p-type Ga.
_From the AlAs mixed crystal ratio of the _0.5 Al _0.5 As clad layer 9,
0.1 higher than 0.6.

In this structure, the current injected from the p-type GaAs contact layer 10 is confined in the window 7a and 780 in the Ga _0.85 Al _0.15 As active layer 4 below the 7a.
Laser oscillation in the nm band occurs. Here, p-type Ga _0.5
The AlAs mixed crystal ratio of the Al _0.5 As first light guide layer 5 is sufficiently higher than the AlAs mixed crystal ratio of the active layer to effectively confine carriers in the active layer and enable oscillation in the visible region with good temperature characteristics. . Specifically, in order to obtain laser oscillation in the 780 nm band having a good temperature characteristic with a characteristic temperature of 150 K or more, an AlAs mixed crystal ratio of 0.45 or more is required. . In the conventional configuration shown in FIG. 15, crystal growth on the first optical guide layer is required. However, regrowth on a layer having an AlAs mixed crystal ratio of 0.3 or more has a problem of surface oxidation, It has been difficult to realize a semiconductor laser with good characteristics in the visible region. In order to solve this problem, in the present invention, a second light guide layer having a low AlAs mixed crystal ratio is introduced on the first light guide layer. That is, FIG.
In re-growth, p-type Ga having a low AlAs mixed crystal ratio was used.
_{Since it} grows on the _0.8 Al _0.2 As second light guide layer 6, there is no problem of surface oxidation. Specifically, the AlAs mixed crystal ratio of the second optical guide layer is set to 0.3, which is easy to regrow.
In the following, it is desirable to be transparent to the laser oscillation wavelength. Therefore, in this embodiment, it is set to 0.2. Further, the layer thickness is desirably 0.05 μm or less which does not significantly affect the light distribution. In this embodiment, 0.0
It is 3 μm. As described above, the layer for confining carriers (first optical guide layer) and the layer to be regrown (second optical guide layer)
Are separately formed, thereby enabling oscillation in the visible region.

In this structure, in order to further improve the confinement of carriers in the active layer, there is a method of introducing a multiple quantum well barrier layer having a high reflectance for electron waves into the first optical guide layer. . FIG. 2A shows a potential energy structure diagram of the multiple quantum well barrier layer. A multiple quantum well barrier layer is formed near the active layer of the first light guide layer in order to prevent overflow of electrons from the active layer. The multiple quantum well barrier layer is composed of two types of semiconductor layers, and has a combination of a periodic structure of the well layer and the barrier layer. The AlAs mixed crystal ratio of the barrier layer was set to 0.5, which is the same as the mixed crystal ratio of the cladding layer. The AlAs mixed crystal ratio of the well layer was set to 0.2 higher than that of the active layer in order to avoid absorption of laser light. According to quantum mechanics, the barrier layer,
As the thickness of each well layer is reduced, high-energy electron waves can be reflected by the active layer. With this effect, electrons can be more effectively confined in the active layer than in the case of a normal double heterojunction, and the characteristic temperature can be improved. However, when the barrier layer becomes thin, the transmission of electrons due to the tunnel effect increases. In consideration of this tunnel effect, in the present embodiment, the thickness of the barrier layer is made thicker near the active layer and thinner as the distance from the active layer increases. FIG. 2B shows the calculation result of the reflectance of this configuration. When there is no multiple quantum well barrier layer, the barrier height for electrons in the active layer and the cladding layer is determined by the classical barrier height (V
₀ ), it can be seen that by introducing the multiple quantum well barrier layer, the reflectivity to an electron wave can be made almost 100% up to a height of 1.3 times the electron energy of V ₀ .
That is, by using the multiple quantum well barrier layer, it becomes possible to effectively confine high energy electrons activated at high temperature in the active layer. In other words, by introducing the multiple quantum well barrier layer, it is possible to realize a semiconductor laser device having an excellent temperature characteristic in which electrons do not overflow from the active layer at a high temperature. The structure of the multi-quantum well barrier layer may have a configuration other than the above as long as the reflectivity of the electron wave is high. Further, the entire first light guide layer may be a multiple quantum well barrier layer.

The forbidden band width of the n-type Ga _0.4 Al _0.6 As current blocking layer 7 is Ga _0.85 Al _0.15 As active layer 4.
Is larger than the forbidden band width, a light blocking element having no light absorption by the current blocking layer and a small operating current with a small loss in the waveguide can be obtained.

Further, in this structure, since there is no light absorption by the current blocking layer, the laser light is n-type Ga _0.4 Al
_The spectrum also spreads below the _0.6 As current blocking layer 7, the spectrum tends to be multimode, and a low-noise laser can be easily obtained. However, it is necessary to reduce the refractive index difference in the horizontal direction to some extent at the junction. For this purpose, it is desirable that the effective refractive index of the layer between the active layer and the current blocking layer is large. In terms of the mixed crystal ratio, the AlAs mixed crystal ratio of the first optical guide layer needs to be as high as that of the cladding layer.

FIG. 3 shows an experimental result of a relationship between a spectrum characteristic and a structural parameter in one embodiment of the present invention. It can be seen that in the 780 nm wavelength band, multimode oscillation is obtained in a wide range of the active layer thickness (da) and the first optical guide layer thickness (dp). The thickness of the second light guide layer is 0.1 mm.
03 μm. Here, the effective refractive index difference in the horizontal direction at the junction of the multimode element was 6 × 10 ⁻³ or less. As described above, in the present invention, light absorption by the current blocking layer is eliminated, and a small effective refractive index difference can be realized.
Multi-mode oscillation is obtained even in a thin region. Since dp may be thin, a low-noise laser can be obtained with a small leakage current to the outside of the stripe. In particular, since da may be thin, a low-noise, high-output laser can be realized. is there.

However, each GaAlAs capable of guiding light can be used.
In the layer, the n-type Ga _0.5 Al _0.5 As cladding layer 3 and the n-type Ga _0.4 Al _0.6 As current blocking layer 7 in the embodiment, as an impurity commonly used in the related art, T
In addition, when Se is added in the metal organic chemical vapor deposition method (MOCVD method), these impurities become DX centers in GaAlAs and have a light density of the main mode oscillating at several mW to several tens mW. Causes a saturable absorption effect.
For this reason, a loss grating is formed for the standing wave of the oscillating main mode, and other modes other than the oscillating main mode are suppressed, thereby increasing the single mode property.

In order to solve this problem, in the embodiment of the present invention, Si is added as an impurity to each layer of GaAlAs that can guide light. Si is D in GaAlAs
Since the activation energy of thermal capture and emission of carriers between the X center level and the conduction band is different from that of Te or Se, light absorption is saturated at a very low optical density and oscillation occurs. Very little loss grating is formed for the main mode. Therefore, there is no problem that the multi-modality of the spectrum is impaired, and the noise can be easily reduced. For the same reason, the use of Si is also effective when the spectrum is made multimode by high-frequency superposition to reduce noise. In other words, in order to reduce the noise in an element structure in which the effective refractive index difference in the horizontal direction is increased at the junction and the oscillation mode spectrum is single mode, high frequency has been conventionally superimposed on the operating current to make the spectrum multimode. However, compared to the case of Te or Se in which a loss grating is formed, the spectrum of multi-mode can be more easily made with Si, and low noise characteristics can be realized.

FIG. 4 shows the relationship between the stripe width and the operating current value. In the structure of the present invention, when the stripe width is reduced, the operating current value is further reduced. Here, in the structure of the present invention, when the stripe width is narrowed, the multi-modality of the spectrum is more increased because light seeping into the current blocking layer is relatively increased as compared with light inside the stripe. It gets even stronger. In other words, by reducing the stripe width, noise can be further reduced.

Here, the design value of the thickness of the first light guide layer will be considered. First, the upper limit of dp will be described.
In order to prevent the waveguide from becoming an anti-guide due to a decrease in the refractive index in the stripe due to the plasma effect and to maintain a stable single transverse mode, the magnitude of the effective refractive index difference Δn inside and outside the stripe must be a certain value or more. Must be.
First, the case where the active layer is made of bulk GaAlAs will be described. At this time, the effective refractive index difference Δn needs to be 4 × 10 ⁻³ or more in order to prevent the waveguide from being anti-guided due to a decrease in the refractive index in the stripe due to the plasma effect. FIG. 5 shows the relationship between the effective refractive index difference Δn and the thickness of the first optical guide layer (d when the current blocking layer is made of AlAs that can maximize the effective refractive index difference Δn inside and outside the stripe.
p). Here, the AlAs mixed crystal ratio of the first optical guide layer and the n-type and p-type cladding layers is set to 0.45 which is a minimum necessary for oscillating in the 780 nm band. The active layer thickness (da) has a vertical divergence angle (θv) of 25 °.
Is set to 0.03 μm. For θv <25 °,
Since the threshold value increases, da = 0.03 μm is the practical lower limit of da. At this time, Δn becomes the largest. From FIG. 5, when the current block layer is made of AlAs,
In order to satisfy Δn ≧ 4 × 10 ⁻³ , dp ≦ 0.51 μm
It turns out that it must be. That is, when the current blocking layer is made of AlAs, dp ≦ 0.51 μm must be satisfied in order to obtain single transverse mode oscillation. However, the upper limit of dp depends on the AlAs mixed crystal ratio of the current blocking layer. That is, when the AlAs mixed crystal ratio of the current blocking layer decreases, the effective refractive index difference Δn at the same dp decreases, and the upper limit of dp also decreases. FIG. 6 shows the relationship between dp (referred to as dp-max) that satisfies Δn = 4 × 10 ⁻³ and the current block layer mixed crystal ratio. The portion below the solid line in the figure is a region where single transverse mode oscillation occurs, and it is necessary to manufacture an element in this region. When the thickness of the active layer is larger than the above, or when the AlAs mixed crystal ratio of the cladding layer is higher than the above, the value of dp-max is slightly smaller than the value of FIG. 6, but at least the value of dp is more than the above. , 0.51 μm is a necessary condition for single transverse mode oscillation.

Next, the lower limit of dp will be described. In FIG.
The relationship between dp and the characteristic temperature (T ₀ ) is shown. dp ≦ 0.0
At 5 μm, there is a problem that the characteristic temperature (T ₀ ) of the semiconductor laser deteriorates because the leakage current increases at high temperatures. Since a decrease in T ₀ leads to a decrease in reliability, at least 130
K or more is necessary. Therefore, it is necessary that dp ≧ 0.05 μm to ensure reliability.

As described above, the refractive index difference Δn between the inside and outside of the stripe
It can be seen that the minimum necessary condition for stably confining the transverse mode and obtaining a highly reliable semiconductor laser is that the first light guide layer thickness dp is 0.05 μm ≦ dp ≦ 0.51 μm.

In order to operate the spectrum only in the single mode, Δn ≧ 6 × 10 ⁻³ is required.
This must be dp ≦ 0.4 μm from FIG.
Therefore, the minimum necessary condition for obtaining a semiconductor laser having a stable transverse mode and a single-mode spectrum is 0.05 μm ≦ dp ≦ 0.4 μm.

Next, the case where the active layer has a quantum well structure will be described. At this time, in order to prevent the waveguide from acting as an anti-guide due to a decrease in the refractive index in the stripe due to the plasma effect, the effective refractive index difference Δn between the inside and the outside of the stripe needs to be 2.5 × 10 ⁻³ or more. There is. FIG. 8 shows a current blocking layer made of AlAs, five Ga _0.7 Al _0.3 As barrier layers each having a thickness of 10 nm giving θv = 25 ° and a thickness of four.
shows the relationship between the Al _0.05 Ga _0. first optical guide layer thickness and the effective refractive index difference Δn of the stripe and out of the laser having a quantum well structure composed of ₉₅ As well layers 4 layers as an active layer of a nm (dp). Also in the case of an active layer having a quantum well structure, the threshold value increases when θv <25 °, so Δn is the largest in this design example. For other active layers with a quantum well structure giving θv> 25 °, Δn will be smaller than in this case. The AlAs mixed crystal ratio of the first optical guide layer and the n-type and p-type claddings is 0.45. From FIG. 8, Δn ≧ 2.5 × 10 ⁻³
It is understood that dp ≦ 0.40 μm must be satisfied in order to satisfy the condition. When dp ≦ 0.05 μm, the characteristic temperature (T ₀ ) becomes low as in the case of the bulk active layer. Therefore, in order to stably confine the transverse mode by the refractive index difference Δn between the inside and outside of the stripe and obtain a highly reliable semiconductor laser, the thickness dp of the first optical guide layer is set to 0.05 ≦ dp.
≦ 0.40 μm.

Further, in order to operate the spectrum only in the single mode, Δn ≧ 6 × 10 ⁻³ or more is required. This must be dp ≦ 0.26 μm according to FIG. Therefore, in order to obtain a semiconductor laser having a stable transverse mode and a single-mode spectrum,
The first light guide layer thickness dp is 0.05 μm ≦ dp ≦ 0.26
μm.

Next, the front end face reflectance of the epitaxially grown layer will be described. In application to a writable optical disk, an optical output of 30 mW or more during writing and a low noise characteristic of -130 dB / Hz or less at 3 mW during reading are required. In a conventional high-power semiconductor laser, a single spectrum has a large noise, and at the time of reading, a method of multiplying a spectrum by superimposing a high frequency is used to reduce noise. As shown in FIG. 3, in the semiconductor laser of the present invention, since the spectrum can be made multimode even when the active layer is thin, a high-output laser with low noise can be realized even without high frequency superimposition. , Dp in the single-mode region of the spectrum will be described.

FIG. 9 shows the relationship between the reflectance of the front end face and the noise characteristics at the time of high frequency superposition. The light output is 3 mW and the return light rate is 5.
5%, optical path length is 50mm, superposition frequency is 600MHz,
The measurement frequency is 5 MHz and the band is 3 KHz. From FIG. 9, in order to obtain a low noise characteristic of -130 dB / Hz or less,
It can be seen that the front end face reflectance needs to be 6% or more. FIG. 10 shows the relationship between the front end face reflectance and the COD (optical end face destruction) light output. To ensure reliability at 30mW, COD output of 40mW or more is required.
FIG. 10 shows that the reflectance needs to be 45% or less.

From the above, it is necessary for the light source for an optical disk to have a front end face reflectivity of 6 to 45%. In the embodiment of the present invention, the reflectivity is set to 11%.

In actual use on an optical disk, there is a case where the return light from the optical disk returns to the substrate of the semiconductor laser. This return light is further reflected on the substrate surface, is superimposed on the signal of the detector, and may cause tracking noise or the like. As a countermeasure, the front end face reflectance on the substrate side is made lower than the front end face reflectance of the epitaxial growth layer. That is, the front end face reflectance of the epitaxial growth layer is set as described above, and only the reflectance on the substrate side is reduced, so that an increase in tracking noise and the like can be suppressed.

FIGS. 11 (a), (b), (c), (d),
(E) is a manufacturing process diagram of the semiconductor laser device in one embodiment of the present invention.

As shown in FIG. 11A, n-type GaAs
An n-type GaAs buffer layer 2 (thickness: 0.5 μm) is formed on an s 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).
04 μm), p-type Ga _0.5 Al _0.5 As first optical guide layer 5 (thickness, 0.22 μm), p-type Ga _0.8 Al _0.2 As
Second light guide layer 6 (thickness: 0.03 μm), n-type Ga
_0.4 Al _0.6 As current blocking layer 7 (thickness, 0.5 μ
m), Ga _0.8 Al _0.2 As protective layer 8 (thickness, 0.01 μm)
m). This protective layer 8 is made of n-type Ga _0.4 Al
_It is necessary to protect the top of the _0.6 As current blocking layer 7 from surface oxidation. Like the second optical guide layer, the AlAs mixed crystal ratio of the protective layer 8 is desirably 0.3 or less, which facilitates regrowth, and is preferably a mixed crystal ratio transparent to laser light. Here, the thickness of the active layer and the thickness of the first light guide layer are set to Δn = 5 × 10 ^{−3 in} order to obtain a stable single transverse mode. In FIG. 11, the conductivity types of the active layer 4 and the protective layer 8 are not particularly described, but may be p-type, n-type, or of course, undoped.

Next, as shown in FIG. 11B, a striped window 7a is formed by etching using a photolithography technique. As an etching method,
First, a Ga _0.4 Al _0.6 A etchant such as tartaric acid or sulfuric acid having a low selectivity to the AlAs mixed crystal ratio is used.
Etching is performed halfway through the s current block layer 7.
Next, using a hydrofluoric acid-based etchant capable of selectively etching a layer having a high AlAs mixed crystal ratio, Ga is selectively used.
_{The 0.4} Al _0.6 As current blocking layer 7 is etched. At this time, the resist may be removed, and the second etching may be performed using the protective layer 8 as a mask. In this second etching, p-type Ga _0.8 Al _{0 .2} As the second optical guide layer 6, to act as an etching stop layer, the variation due to the etching is small, high yield is obtained. The stripe width was 2.0 μm.

As the composition of the hydrofluoric acid etchant, one having a weight ratio to water of 5% to 50% is used. 5%
If it is less than 50%, the current block layer cannot be etched, and
This is because the etching rate is too high to make the control difficult, and the resist used for the mask is eroded.

An etchant obtained by diluting hydrofluoric acid with ammonium fluoride may be used. In this case, the weight ratio of hydrofluoric acid to ammonium fluoride is 25% to 80%. If it is less than 25%, the current blocking layer cannot be etched, and if it exceeds 80%, the etching rate is too fast to control, and the resist used for the mask is eroded.

Further, a mixed solution of hydrofluoric acid and an acid which does not etch GaAlAs by itself may be used as the selective etchant. Examples are shown below.

For example, an etchant containing a mixed solution of phosphoric acid and hydrofluoric acid may be used. In this case, the weight ratio of hydrofluoric acid to phosphoric acid is 5% to 50%. If less than 5%
If the current blocking layer cannot be etched and exceeds 50%, the etching rate is too fast to make it difficult to control, and the resist used for the mask is eroded.

Further, an etchant containing a mixed solution of sulfuric acid and hydrofluoric acid may be used. In this case, the weight ratio of hydrofluoric acid to sulfuric acid is 5% to 80%. If it is less than 5%, the current block layer cannot be etched. If it exceeds 80%, the etching rate is too fast to control, and the resist used for the mask is eroded.

An etchant containing a mixture of hydrochloric acid and hydrofluoric acid may be used. In this case, the weight ratio of hydrofluoric acid to hydrochloric acid is 5% to 80%. If it is less than 5%, the current block layer cannot be etched. If it exceeds 80%, the etching rate is too fast to control, and the resist used for the mask is eroded.

An etchant containing a mixture of tartaric acid and hydrofluoric acid may be used. In this case, the weight ratio of hydrofluoric acid to tartaric acid is 5% to 80%. If it is less than 5%, the current blocking layer cannot be etched, and if it exceeds 80%,
This is because the etch rate is too fast to make the control difficult and the resist used for the mask is eroded.

Further, an etchant containing a mixed solution of acetic acid and hydrofluoric acid may be used. In this case, the weight ratio of hydrofluoric acid to acetic acid is 5% to 80%. If it is less than 5%, the current block layer cannot be etched. If it exceeds 80%, the etching rate is too fast to control, and the resist used for the mask is eroded.

Hydrogen peroxide may be added to the mixture of the above acids to promote the reactivity. Further, in order to reduce the etch rate, it may be diluted with water or ammonium fluoride. In this example, hydrofluoric acid (containing 50%): phosphoric acid (containing 86%): aqueous hydrogen peroxide = 800: 2400: 1 (cc) was used as an etchant.
In this case, the weight ratio of hydrofluoric acid to water is 54% and the weight ratio to phosphoric acid is 19%. FIG. 12 shows the composition dependency and the time dependency of the etching amount of this etchant. FIG. 12A shows that the AlAs mixed crystal ratio is 0.4
It can be seen that the etchant is a selective etchant for a composition exceeding the above. That is, due to this property, only the current blocking layer can be selectively etched on the second light guide layer. This property is not limited to the composition of this etchant, but is common to all of the above-mentioned mixed solutions with hydrofluoric acid, and the selectivity by temperature does not change.

FIG. 12B shows AlAs of the current block layer.
The time dependence of the etching amount when the mixed crystal ratio is 0.65 and the temperature is 20 ° C. is shown. It can be seen that 0.5 μm etching can be performed in about 10 seconds. The etching rate can be freely adjusted by changing the weight ratio of hydrofluoric acid to other liquids. That is, as the concentration of hydrofluoric acid decreases, the etch rate decreases. Further, it is also possible to increase the etching rate by increasing the temperature of the selective etchant. At these times, selectivity is not lost. In this embodiment, the first etching of tartaric acid is performed up to a position just before the second optical guide layer, and then the time of the second selective etching is set to 5 seconds. The etching of the part is realized.

In the above embodiment, only the case where a single layer of the GaAlAs layer is used for the first optical guide layer is shown. However, in order to compare the temperature characteristics, the multiple quantum well barrier layer shown in FIG. An element included in the light guide layer was also manufactured.

Here, the shape of the stripe 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 an inverted mesa shape,
The crystallinity of GaAlAs grown on the side of the window was impaired, and the threshold current of the fabricated device was increased by about 10 mA as compared with the forward mesa-shaped device. The characteristics of the element described later indicate a forward mesa shape.

The impurity concentration n of the current block layer
_{When B} is less than 1 × 10 ¹⁷ cm ⁻³ , the current cannot be confined and the current leaks out of the stripe, resulting in 2 × 10 ¹⁷ cm ^−3.
In the case of ¹⁸ cm ⁻³ or more, the crystallinity of the current blocking layer is deteriorated, so that irregularities are generated on the side surfaces of the striped window during etching. That is, a smooth forward mesa shape cannot be obtained. For this reason, the crystallinity of the p-type cladding layer 9 grown on the side surface of the window is impaired, and the yield is reduced due to the deterioration of the characteristics. Table 1 shows the experimental results. According to Table 1, by setting n _B to 1 × 10 ¹⁷ to 2 × 10 ¹⁸ cm ⁻³ , regrowth with good current confinement and good crystallinity is performed.

[0047]

[Table 1]

Further, regarding the thickness of the current block layer,
When the thickness of the current blocking layer 7 is small, the upper p-type GaAs
Since light absorption of laser light occurs in the s-contact layer 8, at least 0.4 μm is required.

Next, as shown in FIG.
P-type Ga _0.5 Al by VD or MBE growth
_{A 0.5} As cladding layer 9 and a p-type contact layer 10 are formed by regrowth. At this time, a p-type Ga _0.8 Al _0.2 A having a low AlAs mixed crystal ratio is formed in the stripe through which current flows.
Since the growth is performed on the second light guide layer 6, the growth can be easily performed. However, in the case where Zn is used as a dopant for the p-type Ga _0.5 Al _0.5 As cladding layer 9, the internal loss increases due to the diffusion of the Zn stripe region into the active layer during the growth, and the current-light output is increased. The temperature characteristics of the characteristics may be adversely affected. In particular, in the case of an active layer having a quantum well structure, there is a problem that the quantum well is disordered due to diffusion. In order to prevent this, at least the carrier concentration of the p-type layer at the regrowth interface needs to be 10 ¹⁸ cm ⁻³ or less. In this embodiment, 7 × 10 ¹⁷ cm ⁻³
And

As a fundamental countermeasure, carbon, which is a dopant with little diffusion, is replaced with p-type Ga _0.5 Al _0.5 As.
Used as a dopant for the cladding layer 9. By using carbon, it is possible to obtain characteristics with excellent temperature dependence of current-light output characteristics. In the examples, both devices using Zn and carbon were manufactured.

Next, electrodes are formed on the n-type GaAs substrate 1 and the p-type GaAs contact layer 10, respectively.

Finally, the coating will be described. The reflectance of the end face was set to two types. That is, FIG.
As shown in FIG. 14, the coating configuration of the element (FIG. 14) in which the both ends are reduced to 32% for the element whose spectrum is multi-mode and the reflectance at the front end face is reduced in order to obtain high output realizes the design for the optical disk described above. Configuration. The coating process performed to obtain a high output will be described.
First, as shown in FIG. 11D, a dielectric 11 such as alumina is formed on the front end face of the element by sputtering to a thickness having a reflectance of 11%. The rear end face reflectance is set to 75% by the two-layer coat 12 of alumina and silicon. The reflectivity of the rear end face may be a value other than 75%, but it is desirable that the reflectivity be high in order to increase the slope efficiency.

Further, in order to reduce the tracking noise caused by the reflection of the return light on the substrate surface, FIG.
As shown in (e), the reflectance on the substrate side is formed lower than the reflectance on the epitaxially grown portion. That is, the epitaxial growth layer is masked with a resist or the like, and an additional coating of the dielectric film 13 is further performed on the alumina so that the reflectance of the substrate portion is reduced. After that, the resist is removed. In this embodiment, the reflectance of the substrate is set to 3%. There is also a method of reducing the reflectance of the substrate portion by a manufacturing method other than the above. For example, a method in which a dielectric is first coated on the entire front surface to be 3% or less, and then the substrate side is masked with a resist or the like, and the dielectric film of the epitaxial growth layer portion is etched until the reflectance becomes 11%. There is also. With these configurations, it is possible to suppress an increase in noise due to reflection of the return light to the substrate unit.

In the above embodiment, only the case where GaAlAs having a low AlAs mixed crystal ratio is used for the second light guide layer has been described, but other materials which can lattice-match with GaAs may be used. However, in order to suppress light absorption, it is required to have a band gap larger than the wavelength of the laser light. For example, as another embodiment, In _0.5 Ga _0.5 P may be used for the second light guide layer. At this time,
A selective etching method can be used, and since there is no Al in the composition, there is no problem of surface oxidation, and similar characteristics can be obtained.

Also, the same characteristics as described above can be obtained by using In ₁ -x Ga _x As _Y P _{1 -Y} . At this time, X and Y are 0.189Y−0.418X + 0.013XY + in order to obtain lattice matching with GaAs.
It is necessary to satisfy the relationship of 0.127 = 0.

The energy (E) at the wavelength of the laser beam
Than 1.35 + 0.6
72X-1.601Y + 0.758X ² + 0.101Y ² -0.157XY-0.312X ² Y + 0.109X
It is necessary to satisfy the relationship of Y ² > E.

Also in this case, there is no problem of surface oxidation in the manufacturing process, and the etching can be selectively stopped on the second light guide layer.

As another embodiment, In _0.5 (G
a _1-x Al _x ) _0.5 P may be used for the second light guide layer.
In this case, the bandgap becomes larger than the wavelength of the laser beam regardless of X, and lattice matching is obtained. However, if X is too large, there is a problem of oxidation. Therefore, X <0.3 is desirable.
In the etching step, the current block layer can be selectively etched as described above, and the controllability of the etching is improved.

FIG. 13 is a current-light output characteristic diagram of a semiconductor laser device according to one embodiment of the present invention. The end face reflectance is set to 32%. In this embodiment, in order to reduce noise,
Since da = 0.04 μm and dp = 0.22 μm, the spectrum is multimode as shown in FIG. However, since Δn is 5 × 10 ^{−3, the} transverse mode is single.
In a device having a resonator length of 200 μm, an operating current value required to emit 3 mW laser light at room temperature is 25 mA. The transverse mode oscillated in a stable fundamental mode. The spectrum oscillates in multiple modes causing self-pulsation in the 780 nm band, and has a relative intensity noise (RIN) of -130 dB / Hz within a range of the return light rate of 0 to 10%, and has a low noise. Characteristics were obtained. When Zn is used as a dopant during regrowth, the characteristic temperature is about 150K,
When using carbon, the characteristic temperature is about 180K,
It can be seen that an element having excellent temperature characteristics can be obtained by using carbon with little diffusion as the p-type dopant. Furthermore, in the device in which the multiple quantum well barrier layer was introduced into the first light guide layer, a high value of 200K was obtained.

Further, the structure of the present invention has a low operating current value, and is therefore effective for increasing the output of a semiconductor laser. In particular, in this structure, the thickness of the active layer is set to 0.03 to 0.05 μm.
Even when the thickness is reduced as shown in FIG. 3, since the spectrum can be made multi-mode as shown in FIG.
In addition, it is possible to realize a semiconductor laser capable of obtaining a high output in a visible region. If such a semiconductor laser is used as a light source for 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.

If the dp is reduced to reduce the leakage current in the horizontal direction, a single longitudinal mode is obtained, but the output can be further increased. Actually, an active layer thickness of 0.0
3 μm, dp = 0.15 μm, Δn = 7 × 10 ⁻³ , and the current was sufficiently confined, and the cavity was fabricated with a cavity length of 350 μm
By coating the end face for high output,
As shown in FIG. 4, an optical output of 100 mW or more could be obtained. With this coating, a low relative intensity noise of -138 dB / Hz was obtained during high frequency superposition at 3 mW.

Next, in order to improve the performance of the device, an active layer
A case where a quantum well structure is used will be described. Sand
That is, by making the active layer a quantum well structure,
The threshold can be reduced, and high output can be obtained. Quantum well structure
As a 10 nm thick G that oscillates in the 780 nm band.
a_0.95Al_0.054 layers of As well layer, 4 nm thick Ga
_0.7Al_0.3Multi-quantum toe consisting of 5 As barrier layers
Current-optical output characteristics when using a well (MQW) structure
As shown in FIG. dp is 0.2 μm, A of the current blocking layer
The ΔAs mixed crystal ratio was 0.7, and Δn = 6 × 10^-3Toshii
You. 200 mW in the coated device
The above light output can be realized. Composition of coating and
As in the case of the bulk active layer described above, FIG.
From FIG. 10, the light output of 30 mW or more and -130 dB / H
5% to 77% in order to satisfy the low noise characteristic of z or less.
The front end face reflectance is required, and in this embodiment, 14%
I have. At this time, RIN at the time of high frequency superimposition of 3 mW is -1.
It was 42 dB / Hz. In addition, the reflectance of the substrate
As with the bulk active layer described above, lowering the substrate
Tracking noise is reduced by reflection of return light to the
I can do it.

As the quantum well structure of the active layer, other quantum well structures, that is, a single quantum well (SQW) structure, a double quantum well (DQW) structure, a triple quantum well (TQW) structure, and a green (GRIN) structure The structure or its separate confinement heterostructure (SCH) structure may be used.

Also in the case of the quantum well structure, by using carbon as the dopant during regrowth, diffusion of the dopant during growth could be suppressed, and a high characteristic temperature of 250 K was obtained. About 200K when using Zn
Met. When a multiple quantum well barrier layer was provided in the first light guide layer, a very high value of 280 K was obtained.

In all of the above embodiments, only the case where the substrate is an n-type and an n-type current blocking layer is used is shown. However, the substrate may be a p-type and a p-type current blocking layer may be used. I do not care. That is, the AlAs mixed crystal ratio of the current blocking layer is high. This is because, in the case of a p-type GaAlAs layer having a high AlAs mixed crystal ratio, diffusion of electrons is suppressed, so that a p-type block layer can be realized.

In all of the above embodiments, only the case where the current blocking layer is on the active layer, that is, on the side opposite to the substrate when viewed from the active layer, is shown. The same effect is obtained. Alternatively, it is needless to say that the leakage current can be further reduced and the operating current can be reduced by adopting a double configuration structure in which the current block layer is in both directions.

[0067]

As described above, according to the present invention, one conductivity type Ga ₁ -Y ₁ Al _Y1 As is formed on at least one side of the main surface of the active layer.
First light guide layer, Ga _1-Y2 Al _Y2 As, or In
_{0.5 Ga 0 .5 P, In 0.5} (GaAl) 0.5 P, InGaA
While sequentially including a second light guide layer made of sP,
On the second light guide layer, a Ga _{1 -Z} Al _Z As layer having a striped window of the opposite conductivity type is formed, and the striped window has the light guide layer and the A Ga _{1 -Y 3} Al _Y3 As layer of the same conductivity type,
Between the mixed crystal ratios, Y1, Y2, Y3 and Z, Z>Y3>
With the configuration in which the relationship of Y2, Y1> Y2 is established, 78
A semiconductor laser device having a low operating current value in a 0 nm band can be easily realized.

That is, Ga ₁ -Y ₁ having a high AlAs mixed crystal ratio
Carriers are confined in the active layer by the Al _Y1 As first light guide layer, and regrowth is growth in the second light guide layer having a low Al mixed crystal ratio, so that a laser in the visible region can be easily produced.

In particular, by providing a multiple quantum barrier layer in the first light guide layer, it is possible to realize an element having a very high characteristic temperature even in the visible region.

Further, at the time of etching for forming a stripe, a selective etching method based on a difference in AlAs mixed crystal ratio can be used, so that the variation in etching is reduced.
High yield can be obtained.

Further, when the buried layer is p-type, the diffusion of the p-type dopant into the active layer at the time of regrowth can be suppressed by using carbon as the dopant at the time of regrowth. An element having excellent dependence can be obtained.

Further, when the current block layer is n-type,
Pure substance concentration of 10¹⁷~ 2 × 10¹⁸cm ^-3By doing
Current confinement and striped window etch
Good growth and growth on the side of the window, resulting in high yield
You.

Further, 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 of the laser beam by the current blocking layer. Therefore, a low operating current value can be obtained.

Here, by setting the thickness of the first optical guide layer to be 0.05 μm to 0.51 μm for the bulk active layer and 0.05 μm to 0.40 μm for the quantum well active layer,
It realizes stable single transverse mode oscillation and high reliability.

Further, the light spreads to the current blocking layer and the active layer thereunder, and the first optical guide layer having a high AlAs mixed crystal ratio can form a small difference in the effective refractive index in the horizontal direction at the junction. Mode oscillation can be easily obtained, and low noise characteristics can be obtained. In particular, the use of Si as a dopant for the n-type GaAlAs layer through which light can be guided facilitates multi-mode spectrum.

Further, by setting the front end face reflectivity of the epitaxial growth layer to 6 to 45% for the bulk active layer and 5 to 77% for the quantum well active layer, it is possible to obtain a light output suitable for a rewritable optical disk. Noise characteristics can be obtained. Furthermore, by making the reflectance of the substrate lower than the reflectance of the epitaxially grown portion, it is possible to reduce the noise due to the reflection of the return light on the substrate.

A laser having a low noise and a low operating current in the 780 nm band is most suitable as a light source for an optical disk including a compact disk. In particular, 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, the laser package, which has conventionally been made of metal, can be made of resin, and the size and cost of the pickup can be significantly reduced.

Further, since a lower operating current results in a reduction in the amount of heat generated in the active layer, a higher output can be obtained. Particularly when the active layer has a quantum well structure, higher output can be obtained. If the 780 nm band semiconductor laser of the present invention having such low noise and high output characteristics is used as a light source of an optical disk, it becomes possible to eliminate a high frequency superimposing circuit for reducing noise at the time of reading, and a 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. 2 shows the structure of a multiple quantum well barrier layer according to one embodiment of the present invention, and the calculation result of reflectivity for electrons.

FIG. 3 Relationship between spectral characteristics and structural parameters

FIG. 4 shows a relationship between an operating current value and a stripe width.

FIG. 5 is a relationship between dp and Δn.

FIG. 6 shows the relationship between the mixed crystal ratio (X _B ) of the current blocking layer and the maximum dp (dp-max) that results in a single transverse mode.

FIG. 7: Relationship between dp and T ₀

FIG. 8 shows the relationship between dp and Δn in the case of a quantum well active layer.

FIG. 9 shows the relationship between the front end face reflectance and RIN.

FIG. 10 shows a relationship between front end face reflectance and COD light output.

FIG. 11 is a manufacturing process diagram of the semiconductor laser device in one embodiment of the present invention.

FIG. 12 shows composition dependence and time dependence of an etching amount.

FIG. 13 is a current-light output characteristic diagram of a semiconductor laser device according to one embodiment of the present invention.

FIG. 14 is a graph showing current-light output characteristics of a semiconductor laser device according to an embodiment of the present invention.

FIG. 15 is a sectional view of a conventional semiconductor laser device.

[Explanation of symbols]

Reference Signs List 1 n-type GaAs substrate 2 n-type GaAs buffer layer 3 n-type Ga _0.5 Al _0.5 As clad layer 4 Ga _0.85 Al _0.15 As active layer 5 p-type Ga _0.5 Al _0.5 As first optical guide layer 6 p-type Ga _0.8 Al _0.2 As second light guide layer 7 n-type Ga _0.4 Al _0.6 As current blocking layer 7 a striped window 8 p-type Ga _0.8 Al _0.2 As protective layer 9 p-type Ga _0.5 Al _0.5 As cladding layer 10 p-type GaAs contact layer 11 front end face coating film 12 rear end face coating film 13 coating film for reducing the reflectance of the substrate 21 n-type GaAs substrate 22 n-type Ga _0.65 Al _0.35 As cladding layer 23 GaAs active layer 24 p-type Ga _0.75 Al _0.25 As first cladding layer 25 n-type Ga _0.51 Al _0.49 As current blocking layer 25a stripe of 26 p-type Ga _0.75 Al _0.25 As GaAs contact layer of the second cladding layer 27 p-type

──────────────────────────────────────────────────続 き Continued on the front page (31) Priority claim number Japanese Patent Application No. 4-156560 (32) Priority date Hei 4 (1992) June 16 (33) Priority claim country Japan (JP) (31) Priority Claim No. Hei 4-2554537 (32) Priority Date Hei 4 (September 24, 1992) (33) Country of priority claim Japan (JP) (31) Claim number of priority claim Japanese Patent Application No. 4-259303 (32) Priority Heisei 4 (1992) September 29 (33) Priority claiming country Japan (JP) (31) Priority claim number Japanese Patent Application No. 4-288550 (32) Priority date Hei 4 (1992) October 27 (33) ) Priority claiming country Japan (JP) (31) Priority claim number Japanese Patent Application No. 4-288553 (32) Priority date Heisei 4 (1992) October 27 (33) Priority claiming country Japan (JP) Application (72) Inventor Masahiro Kume 1006 Kadoma, Kadoma, Osaka Prefecture Inside Matsushita Denshi Kogyo Co., Ltd. (72) Kunio Ito Odaka, Kadoma, Osaka 1006 Shin Matsushita Denko Kogyo Co., Ltd. (72) Inventor Kazunari Ota 1006 Kadoma, Kadoma-shi, Osaka Prefecture Matsushita Denko Kogyo Co., Ltd. (56) References JP-A-6-53608 (JP, A) JP-A-6-77594 (JP, A) JP-A-6-132607 (JP, A) JP-A-60-110188 ( JP, A) JP-A-2-213181 (JP, A) JP-A-60-147119 (JP, A) JP-A-62-176183 (JP, A) JP-A-61-220490 (JP, A) 60-136165 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) H01S 3/18

Claims (31)

(57) [Claims] 1. A on at least one side of the main surface of the active layer to become Ga _1-X Al _X As layer, the one conductivity type Ga _1-Y1 Al _Y1 A
a first light guide layer, a Ga _{1 -Y 2} Al _{Y 2} As second light guide layer, and a Ga ₁ having a striped window of the opposite conductivity type on the second light guide layer. _-Z
Al _Z As current blocking layer is formed, the stripe-shaped window, of the same conductivity type as the light guide layer Ga
_1-Y3 Al _Y3 As clad layer is provided, and Z>Y3> between AlAs mixed crystal ratio, X, Y1, Y2, Y3 and Z.
A semiconductor laser device, wherein a relationship of Y2> X ≧ 0 and Y1> Y2 is satisfied. 2. A first light guide layer including a multi-quantum well barrier layer of one conductivity type, Ga _1-Y2 Al _Y2 on at least one side of a main surface of a Ga _1-x Al _x As layer serving as an active layer. As a second light guide layer is sequentially provided, and a stripe-shaped window having the opposite conductivity type to the second light guide layer is provided on the second light guide layer.
a _1-Z Al _Z As current blocking layer is formed, and the stripe-shaped window is provided with a Ga _{1 -Y 3} Al _Y3 As layer of the same conductivity type as the light guide layer, and an AlAs mixed crystal ratio ,
Between X, Y2, Y3 and Z, Z>Y3>Y2> X ≧
A semiconductor laser device wherein a relationship of 0 is established. On at least one side of the main surface of wherein the active layer Ga _1-X Al _X As layer, the first light guide layer including a multiple quantum well barrier layer of one conductivity type, the In _0.5 Ga _0.5 P G having two light guide layers in sequence and having a striped window on the second light guide layer having the opposite conductivity type to the second light guide layer.
a _1-Z Al _Z As current is blocking layer is formed on the stripe-shaped window is made includes a Ga _1-Y3 Al _Y3 As cladding layer of the same conductivity type as the light guide layer, AlAs
A semiconductor laser device wherein a relationship of Z>Y3> X ≧ 0 is established among the mixed crystal ratios, X, Y3 and Z. 4. A first light guide layer including a multi-quantum well barrier layer of one conductivity type and an InGaAsP second light guide layer on at least one side of a main surface of a Ga _1-x Al _x As layer serving as an active layer. Sequentially, and on the second light guide layer,
Ga of the opposite conductivity type and having a striped window
_1-Z Al _Z As current blocking layer is formed, the stripe-shaped window, of the same conductivity type as the light guide layer G
a _1-Y3 Al _Y3 As cladding layer, wherein a relationship of Z>Y3> X ≧ 0 is established among AlAs mixed crystal ratios, X, Y3 and Z. 5. A first light guide layer including a multi-quantum well barrier layer of one conductivity type, In _0.5 (GaAl) _0.5 on at least one side of a main surface of a Ga _1-x Al _x As layer serving as an active layer. A Ga _{1 -Z} Al _Z As current blocking layer having a striped window of the opposite conductivity type is formed on the second light guide layer while sequentially providing a P second light guide layer. The stripe-shaped window includes a Ga _{1 -Y 3} Al _Y3 As clad layer of the same conductivity type as the light guide layer,
AlAs mixed crystal ratio, between X, Y3 and Z, Z>Y3>
A semiconductor laser device, wherein a relationship of X ≧ 0 is satisfied. 6. The method of claim 1 film <br/> thick Ga _1-Y1 Al _Y1 As the first light guide layer is not more than 0.51μm exceed 0.1 [mu] m
Serial mounting semiconductor laser device. 7. A layer of one conductivity type is p- type and n-type Ga _{1 -Z}
The impurity concentration of the al _Z As current blocking layer is 1 × 10 ¹⁷ ~
2. The method according to claim 1, wherein the size is 2 × 10 ¹⁸ cm ^−3.
3, the semiconductor laser device according to claim 4 or claim 5 Symbol mounting. 8. The p-type Ga _{1 -Y 3 wherein the} one conductivity type layer is p- type.
Al _Y3 As claim 1 that addition of carbon as an impurity of the cladding layer, claim 2, claim 3, claim 4 or
The semiconductor laser device according to claim 5 Symbol mounting. 9. The first, second, third and fourth embodiments wherein the front end face reflectivity of the epitaxially grown layer is 6 to 45%.
Or fifth Kouki mounting the semiconductor laser device. 10. The front facet reflectance of the epitaxially grown layer is 6 to 45%, and the reflectance of at least a part of the front facet of the GaAs substrate is lower than the front facet reflectance of the epitaxially grown layer. Claim 1, Claim 2, Claim 3, Claim 4 or
Motomeko 5 Symbol mounting the semiconductor laser device. On at least one side of the 11. main surface of the active layer of quantum well structure, one conductivity type Ga _1-Y1 Al _Y1 As the first light guide layer of, Ga _1-Y2 Al _Y2 As the second optical guide layer Sequentially
And a Ga _{1 -Z} Al _Z As having a striped window of the opposite conductivity type on the second light guide layer.
A current blocking layer is formed, and Ga _{1 -Y 3} Al _{Y 3} of the same conductivity type as the light guide layer is provided in the stripe-shaped window.
Be provided with the As class head layer, AlAs mixed crystal ratio, Y1,
Between Y2, Y3 and Z, Z>Y3> Y2 > 0 , Y1
> Y2 > 0. A semiconductor laser device characterized by satisfying the relationship of : > Y2 > 0 . 12. A first optical guide layer including a multi-quantum well barrier layer of one conductivity type and a Ga _{1 -Y2} Al _Y2 As second optical guide layer on at least one side of a main surface of an active layer having a quantum well structure. And a Ga _{1 -Z} A having a striped window of the opposite conductivity type on the second light guide layer.
l _Z As current blocking layer is formed, the stripe-shaped window, of the same conductivity type as the light guide layer Ga
A semiconductor laser device comprising a _1-Y3 Al _Y3 As cladding layer, wherein a relationship of Z>Y3> Y2 is established among AlAs mixed crystal ratios, Y2, Y3 and Z. 13. A first light guide layer including a multi-quantum well barrier layer of one conductivity type and an In _0.5 Ga _0.5 P second light guide layer are sequentially formed on at least one side of a main surface of an active layer having a quantum well structure. And a Ga _{1 -Z} Al _Z having a striped window of the opposite conductivity type on the second light guide layer.
An As current blocking layer is formed, and Ga _{1 -Y 3} A of the same conductivity type as the light guide layer is provided in the stripe-shaped window.
l _Y3 As clad layer, AlAs mixed crystal ratio, Y
3. A semiconductor laser device wherein a relationship of Z> Y3 is established between 3 and Z. 14. A first light guide layer including a multi-quantum well barrier layer of one conductivity type and an InGaAsP second light guide layer are sequentially provided on at least one side of a main surface of an active layer having a quantum well structure, On the second light guide layer, Ga _{1 -Z} Al _Z having a striped window of the opposite conductivity type.
An As current blocking layer is formed, and Ga _{1 -Y 3} A of the same conductivity type as the light guide layer is provided in the stripe-shaped window.
l _Y3 As clad layer, AlAs mixed crystal ratio, Y
3. A semiconductor laser device wherein a relationship of Z> Y3 is established between 3 and Z. 15. A first light guide layer including a multi-quantum well barrier layer of one conductivity type on at least one side of a main surface of an active layer having a quantum well structure, and an In _0.5 (GaAl) _0.5 P second light guide layer. And a striped window having the opposite conductivity type on the second light guide layer.
a _1-Z Al _Z As current is blocking layer is formed on the stripe-shaped window is made includes a Ga _1-Y3 Al _Y3 As cladding layer of the same conductivity type as the light guide layer, AlAs
A semiconductor laser device wherein a relationship of Z> Y3 is established between the mixed crystal ratio, Y3 and Z. 16. The first optical guide layer of Ga _{1 -Y 1} Al _Y1 As .
Claim thickness is less than 0.40μm exceed 0.1 [mu] m
12. The semiconductor laser device according to item 11 . 17. The one conductivity type layer is p- type and n-type Ga
The impurity concentration of the _1-Z Al _Z As current blocking layer is 1 × 10 ¹⁷
~2 × 10 ¹⁸ cm ^-3 in a claim 11, claim 12,請
The semiconductor laser device according to claim 13, claim 14, or claim 15 . 18. The p-type Ga layer according to claim 18, wherein the one conductivity type layer is p- type.
12. The method according to claim 11, wherein carbon is added as an impurity of the _1-Y3 Al _Y3 As cladding layer.
16. The semiconductor laser device according to claim 14 or 15 . 19. The method of claim 11 front surface reflectivity of the epitaxially grown layer is from 5 to 77%, according to claim 12, wherein
16. The semiconductor laser device according to claim 13, 14, or 15 . 20. The front facet reflectivity of the epitaxially grown layer is 5 to 77%, and the reflectivity of at least a part of the front end face of the GaAs substrate is lower than the front facet reflectivity of the epitaxially grown layer. Claim 11, Claim 12, Claim 13, Claim 14
Or a semiconductor laser device according to claim 15 . 21. A _first conductivity type Ga ₁ -Y ₁ Al _Y1 As first light guide layer, G on at least one side of the main surface of the active layer.
a _1-Y2 Al _Y2 As second light guide layer, and a Ga _1-Z Al _Z As current block layer of the opposite conductivity type to the light guide layer,
Forming by epitaxial growth;
_{A step} of selectively etching only the _1-Z Al _Z As current blocking layer in a stripe shape with a mixed solution of hydrofluoric acid and a diluting solution; and a step of etching the stripe-shaped portion with the same conductivity type as the light guide layer. Forming a Ga ₁ -Y ₃ Al _Y3 As clad layer by epitaxial growth;
s mixed crystal ratio, between Y1, Y2, Y3 and Z, Z> Y3
> Y2, Y1> Y2. 22. A _first conductivity type Ga ₁ -Y ₁ Al _Y1 As first light guide layer, I on one side of the main surface of the active layer.
n _0.5 Ga _0.5 P second optical guide layer, a Ga _1-Z Al _Z As current blocking layer of the optical guide layer and the opposite conductivity type, sequentially forming by epitaxial growth, the Ga _1-Z
Al _Z and As current blocking layer only selectively striped, and etching with a mixture of hydrofluoric acid and the diluent, of the same conductivity type as the light guide layer etched portion to said stripe Ga _1- A step of forming a _Y3 Al _Y3 As clad layer by epitaxial growth;
s mixed crystal ratio, between Y1, Y3 and Z: Z> Y3, Z>
A method for manufacturing a semiconductor laser device, wherein the relationship of Y1 is established. 23. A one-conductivity-type Ga ₁ -Y ₁ Al _Y1 As first light guide layer, I, on at least one side of the main surface of the active layer.
sequentially forming, by epitaxial growth, an nGaAsP second light guide layer and a Ga ₁ -Z Al _Z As current blocking layer of a conductivity type opposite to that of the light guide layer; and forming the Ga _{1 -Z} A
l _Z of As current blocking layer only selectively striped, and etching with a mixture of hydrofluoric acid and the diluent, of the same conductivity type as the light guide layer etched portion to said stripe Ga _1- A step of forming a _Y3 Al _Y3 As clad layer by epitaxial growth;
s mixed crystal ratio, between Y1, Y3 and Z: Z> Y3, Z>
A method for manufacturing a semiconductor laser device, wherein the relationship of Y1 is established. 24. A _first conductivity type Ga ₁ -Y ₁ Al _Y1 As first light guide layer and a one conductivity type In _0.5 (GaAl) _0.5 P second light guide layer on at least one side of the main surface of the active layer. , A Ga _{1 -Z} Al _Z As current block having a conductivity type opposite to that of the light guide layer.
The click layer, successively, a step of forming by epitaxial growth, the Ga _1-Z Al _Z As current blocking layer only selectively stripes edge <br/> quenching with a mixture of hydrofluoric acid and the diluent And the same conductive type Ga _{1 -Y 3} Al _Y3 A as the light guide layer is formed in the striped portion.
a step of forming an s clad layer by epitaxial growth, wherein an AlAs mixed crystal ratio, Y1, Y3 and Z
A method for manufacturing a semiconductor laser device, wherein a relationship of Z> Y3 and Z> Y1 is satisfied. 25. The step of etching, comprising: Ga _{1 -Z} Al _Z
The As current blocking layer weight ratio of water hydrofluoric acid 5%
22. The method of claim 21, wherein the etching is selectively performed in a stripe shape with an etchant of about 50%.
A method for manufacturing a semiconductor laser device according to claim 23 or claim 24 . 26. An etching step comprising the steps of: Ga _{1 -Z} Al _Z
22. The As current blocking layer is selectively etched in a stripe shape with an etchant having a weight ratio of hydrofluoric acid to ammonium fluoride of 25% to 80% .
A method for manufacturing a semiconductor laser device according to claim 22, 23 or 24 . 27. An etching step comprising the steps of: Ga _{1 -Z} Al _Z
21. The As current blocking layer is to weight ratio phosphoric acid hydrofluoric acid etch to selectively striped with 5% to 50% of the etchant, claim 22,請
A method for manufacturing a semiconductor laser device according to claim 23 or claim 24 . 28. The method according to claim 28, wherein the step of etching is Ga _{1 -Z} Al _Z
The As current blocking layer weight ratio of sulfuric acid hydrofluoric acid 5
23. The method according to claim 21, wherein said etching is selectively performed in a striped shape with an etchant of% to 80%.
A method for manufacturing a semiconductor laser device according to claim 23 or claim 24 . 29. The step of etching comprises : Ga _{1 -Z} Al _Z
The As current blocking layer weight ratio of hydrochloric acid hydrofluoric acid 5
23. The method according to claim 21, wherein said etching is selectively performed in a striped shape with an etchant of% to 80%.
A method for manufacturing a semiconductor laser device according to claim 23 or claim 24 . 30. An etching step comprising the steps of: Ga _{1 -Z} Al _Z
21. The As current blocking layer is to weight ratio tartaric hydrofluoric acid etch to selectively striped with 5% to 80% of the etchant, claim 22,請
A method for manufacturing a semiconductor laser device according to claim 23 or claim 24 . 31. An etching step comprising the steps of: Ga _{1 -Z} Al _Z
The As current blocking layer weight ratio of acetic hydrofluoric acid 5
23. The method according to claim 21, wherein said etching is selectively performed in a striped shape with an etchant of% to 80%.
A method for manufacturing a semiconductor laser device according to claim 23 or claim 24 .