JPH0794830A - Semiconductor laser element and its manufacturing method - Google Patents

Abstract

PURPOSE:To suppress end face damage due to heat and achieve a high output by enabling an activated layer to be in recessed structure as compared with an element end face and a part which is adjacent to the activated layer of a clad layer to be gradually recessed toward the activated layer. CONSTITUTION:N-type clad layer 2, multiple quantum well activated layer 3, and p-type contact layer 5 are successively subjected to crystal growth on n-type substrate 1. The multiple quantum well activated layer 3 is formed by alternately laminating three well layers 6 and four barrier layers 7. Then, a stripe-shaped SiO2 film is formed on the upper surface of the contact layer 5. After the p-type contact layer 5 and the p-type clad layer 4 are partially etched with the film as a mask, the n-type block layer 8 is selectively grown at a region without this film. For reducing element resistance, after the SiO2 film is eliminated, a buried layer 9 and a cap layer 10 are formed. Then, an electrode 11 is formed on the surface of a wafer, the substrate 1 is etched by approximately 100mum, and then an electrode 12 is formed on it.

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, and more particularly to a high power semiconductor laser device used as a light source for a laser beam printer, an optical disk, a laser processing apparatus and the like and a method for manufacturing the same.

[0002]

2. Description of the Related Art A conventional high power semiconductor laser device is shown in FIG.
As shown in the perspective view of FIG. 1, a substrate 26, a block layer 27, a clad layer 28, an active layer 29, a clad layer 30, and a cap layer 31 are sequentially laminated, and the surface of the emitting end face that emits light is made of Al ₂ O ₃ or the like. The insulating film 13 is covered to prevent chemical reaction, thereby preventing the end face from being chemically damaged. Documents describing such high-power semiconductor lasers include J. Peek, et al.
IEE Journal of Quantum Electronics "IEEE J. of Quant. Elec."
QE-17 (5), p. 781, 1981).

[0003]

In the conventional high-power semiconductor laser described above, at least the end faces of the cladding layers 28, 30 and the active layer 29 on the light emitting side are flat, and the emitting end faces are flat. A laminate of the respective layers is cleaved, and the insulating film 13 is directly formed on the cleaved surface.
Therefore, although the radiation end face of the semiconductor laser can be protected from chemical corrosion, the interface state generated at the interface between the semiconductor and the insulating film cannot be completely removed, and the end face destruction due to the heat generated by the interface recombination is destroyed. May occur. This is because the higher the output of the semiconductor laser, the more easily the end face is destroyed.

Several structures have been proposed as a method of improving this and completely protecting the end face. For example, JP-A-63
Japanese Patent Laid-Open No. 216396 discloses a window structure in which the active layer exposed on the end face is replaced with a crystal that does not absorb laser light as a means for obtaining a larger end face protection effect. Further, Japanese Patent Laid-Open No. 64-86585 proposes a structure in which the active layer in the end face region is formed by bending and the active layer is removed to prevent light from being guided to the curved portion. . However, these structures have the drawback of requiring complicated and poorly reproducible fabrication steps for edge protection.

An object of the present invention is to realize a semiconductor laser device capable of suppressing damage to the end surface due to heat and producing a high output.

Another object of the present invention is to realize a manufacturing method for obtaining a semiconductor laser device which achieves the above object by a simple method.

[0007]

In order to achieve the above object, the present invention has a structure in which at least the active layer is recessed toward the inside of the crystal on the end face of the semiconductor laser device. The present invention includes not only the configuration in which only the active layer is recessed from the element end face, but also the configuration in which the clad layer is gradually recessed as the portion adjacent to the active layer is closer to the active layer side.

Such a recess is formed by cleaving a semiconductor laser wafer into a bar shape and then corroding the active layer with an etching solution for selectively etching the active layer. Further, in order to reduce the surface level formed by chemical etching, the surface of the semiconductor crystal is cleaned with a cleaning liquid containing a Group VI compound such as sulfur, selenium, and tellurium, and sulfur, selenium, tellurium, etc. are applied to the end surface of the active layer. Attach. The recess of the active layer may be formed on both end faces of the semiconductor laser.

[0009]

The heat generated by the surface recombination of the semiconductor laser is mainly conducted and dissipated through the crystallographically continuous semiconductor crystal. As shown by the isotherm 44 of FIG. 6A, in the case of the active layer 41 extending to the end face, the heat generation face is on the surface of the crystal, so the heat generated at the end face 42 of the active layer includes the semiconductor including the cladding layer 43. The inside spreads out in a semi-circular shape. On the other hand, as shown in FIG. 6B, in the case where the active layer end face 45 is recessed in the crystal as in the present invention, heat spreads in a circular shape centering on the active layer end face 45. . Therefore, the isotherm 4 of FIG.
As shown in FIG. 6, the thermal resistance near the active layer is smaller than that in the case of FIG. As a result, the temperature rise of the end face of the semiconductor laser is prevented and the light output is increased.

However, if the recess of the active layer is too deep, the end face of the active layer loses its function as a reflecting surface. For example, JP-A-58
Although a distributed feedback type semiconductor laser is described in Japanese Laid-Open Patent Application No. 58784, the Fabry-Perot mode is suppressed by utilizing the end face having a deep recess in reverse. On the contrary,
In the Fabry-Perot type semiconductor laser according to the present invention, it is necessary to set the depth of the recess within a range in which the function of the end face as a reflector is not lost so as not to impair the function of the end face as a reflection surface. FIG. 7 shows the result of measurement of the relationship between the etching depth and the end face destruction light output. From this figure, the etching amount is required to be about 50 nm to 300 nm in order to set the end face destruction light output to 150 mW or more.

Further, although the surface level of the crystal itself tends to be reduced by the chemical etching, it is possible to use only the effect of reducing the surface level by avoiding the complicated change of the surface shape due to the etching by etching only the active layer. There are advantages. As a structure for compensating the optical waveguide, it is effective to provide an optical guide layer which is not etched during the etching of the active layer between the active layer and the cladding layer of the semiconductor laser. Further, by making the bottom surface of the etched active layer a chemically stable (111) surface, a further effect can be obtained. Further, when a Group VI compound such as sulfur, selenium or tellurium is adsorbed on the surface of the semiconductor crystal to stabilize the surface level, a greater effect can be obtained.

[0012]

Embodiments of the present invention will be described with reference to the drawings.

<Embodiment 1> FIG. 1 is a diagram showing the structure of a first embodiment of a semiconductor laser device according to the present invention. FIG. 1A is a perspective view of a semiconductor laser wafer in a manufacturing process.
(B) is a side sectional view of the semiconductor laser device. In this embodiment, n-type Al _0.5 Ga _0.5 As is formed on the n-type GaAs substrate 1.
Cladding layer 2, multiple quantum well active layer 3, p-type Al _0.5 G
a _0.5 As clad layer 4, p-type GaAs contact layer 5
Were sequentially grown. The multiple quantum well active layer 3 is formed by alternately stacking three GaAs well layers 6 and four Al _0.3 Ga _0.7 As barrier layers 7 as shown in a partially enlarged view.

Next, a stripe-shaped SiO ₂ film is formed on the upper surface of the contact layer 5 of this structure by using the thermal CVD method and the photolithographic technique. Using this SiO ₂ film as a mask, the p-type GaAs contact layer 5 and the p-type Al _0.5 Ga _0.5 A are formed.
After etching a part of the s clad layer 4, the n-type GaAs block layer 8 was selectively grown in the region without the SiO ₂ film by the metal organic chemical vapor deposition method. In order to reduce the series resistance of the device, after removing the SiO ₂ film, p-type Al _0.5 G
An a _0.5 As embedded layer 9 and a p-type GaAs cap layer 10 were formed. Next, an electrode 11 containing Au as a main component is formed on the surface of the wafer, and the GaAs substrate 1 is etched to about 100 μm by mechanical polishing and chemical etching.
The electrode 12 containing Au as a main component was also formed on the s substrate 1 side. This semiconductor wafer was cleaved into bars at intervals of about 600 μm. FIG. 1A shows a perspective view of the semiconductor laser device at this stage.

Next, the multiple quantum well active layer 3 exposed on the surface cleaved in the shape of the bar was etched about 150 nm inward from the cleavage surface with an ammonia-based etching solution. At this time, the etching solution is HN ₄ OH: H ₂ O ₂ : H ₂ O =
1: 100: 1000, and about 10 devices in this liquid.
Soaked for a second. The etching rate ratio between the active layer and the cladding layer is about 20: 1. This makes Al
_{The 0.5} Ga _0.5 As cladding layers 2 and 4 are hardly etched by the ammonia-based etching solution. Therefore,
As shown in the side view of FIG. 1B, the active layer 3 has a concave shape on the cleaved end face. The front end face (light emitting face) of this semiconductor laser device is provided with an antireflection coating 13 of Al ₂ O ₃ (reflectance 5%), and the rear end face of the device is made of high-reflection amorphous Si / Al ₂ O _3. Coating 14 (reflectance 90%) was applied. Examples of the organic acid suitable for the selective etching include tartaric acid, citric acid, acetic acid and the like. In addition, the composition of these organic acids is GaAs
It is also possible to select to etch only the well layer, remove the GaAs well layer, and then etch the Al _0.3 Ga _0.7 As barrier layer with a (NH ₃ ) S _X solution to obtain a desired shape. In this case, in addition to the shape effect due to etching, (NH ₃ ) S
_The surface stabilization effect of _{X is} also obtained, and higher output and higher reliability are possible. As shown in FIG. 1, a gap is generally formed between the recessed portion of the active layer 3 and the antireflection coating 13. However, this void may not occur depending on the coating material.

The semiconductor laser of this embodiment could be stably operated at 70 ° C. and an optical output of 100 mW for 10,000 hours or more.

<Embodiment 2> FIG. 2 is a diagram showing the structure of a second embodiment of the semiconductor laser device according to the present invention, in which (a) is a perspective view of a semiconductor laser wafer in the manufacturing process,
(B) is a side sectional view of the semiconductor laser device. The same parts as those in FIG. 1 are designated by the same reference numerals.

In this embodiment, on the n-type GaAs substrate 1,
n-type (Al _0.7 Ga _0.3 ) _0.5 In _0.5 P cladding layer 15, multiple quantum well active layer 16, p-type (Al _0.7 Ga _0.3 ) _0.5 In
_{The 0.5} P clad layer 17 and the p-type Ga _0.5 In _0.5 P contact layer 18 were sequentially crystal-grown. As shown in the enlarged circle, the multi-quantum well active layer 16 comprises five Ga _0.5 In _0.5 P well layers 19 and four (Al _0.7 Ga _0.3 ) _0.5 In _0.5 P barrier layers 20 alternately stacked. Is forming.

Next, thermal CVD is performed on the surface of the contact layer 18.
Of stripes using the method and photolithographic technique
An O ₂ film is formed. Using this SiO ₂ film as a mask, the p-type Ga _0.5 In _0.5 P contact layer 18 and the p-type (Al _0.7 G
After a part of the a _0.3 ) _0.5 In _0.5 P clad layer 17 was etched, the n-type GaAs block layer 8 was selectively grown in the region without the SiO ₂ film by the metal organic chemical vapor deposition method.
In order to reduce the series resistance of the device, the p-type Al _0.5 Ga _0.5 As buried layer 9 and the p-type GaAs cap layer 10 were formed after removing the SiO ₂ film. Next, the electrode 11 containing Au as a main component is formed on the surface of the cap layer 10, the GaAs substrate 1 is etched to about 100 μm by mechanical polishing and chemical etching, and the lower side of the GaAs substrate 1 also contains Au as a main component. The electrode 12 was formed.

The semiconductor wafer obtained as described above was cleaved into bars at intervals of about 600 μm. FIG. 2A shows a sectional shape of the semiconductor laser device at this stage. next,
The multiple quantum well active layer 16 exposed on this bar-shaped cleavage plane was etched by about 150 nm with a hydrochloric acid-based etching solution. At this time, since the (AlGa) InP clad layers 15 and 17 are not etched by the hydrochloric acid solution,
As shown in the side sectional view of (b), the active layer 16 portion has a concave shape. A is formed on the front end face of this semiconductor laser device.
l ₂ O ₃ anti-reflection coating 13 (reflectance 5%),
A highly reflective coating 14 (reflectance 90%) composed of amorphous Si / Al ₂ O ₃ was applied to the rear end surface of the device.

The semiconductor laser of this example could be stably operated at 70 ° C. and an optical output of 50 mW for 10,000 hours or more.

<Embodiment 3> FIG. 3 is a diagram showing the structure of a third embodiment of the semiconductor laser device according to the present invention. FIG. 3A is a perspective view during the fabrication of the device, and FIG. It is a sectional side view. The same parts as those in FIGS. In this embodiment, the n-type GaAs substrate 1 is first manufactured.
An n-type Ga _0.5 In _0.5 P clad layer 21, a single quantum well active layer 22, and a p-type Ga _0.5 In _0.5 P clad layer 2 are formed on the top.
3. The p-type Ga _0.5 In _0.5 P contact layer 18 was sequentially crystal-grown. As shown in the circular enlarged view, the single quantum well active layer 22 is formed by sandwiching a single Ga _0.8 In _0.2 As well layer 24 between two GaAs guide layers 25.

Next, a striped SiO ₂ film is formed on the upper surface of the contact layer 18 of this structure by using the thermal CVD method and the photolithographic technique. Using this SiO ₂ film as a mask, the p-type Ga _0.5 In _0.5 P contact layer 18 and the p-type G
After etching a part of the a _0.5 In _0.5 P clad layer 23, the n-type GaAs block layer 8 was selectively grown in the region without the SiO ₂ film by the metal organic chemical vapor deposition method. In order to reduce the series resistance of the device, the p-type Al _0.5 Ga _0.5 As embedded layer 9 and the p-type GaAs cap layer 10 were formed after removing the SiO ₂ film.

Next, an electrode 11 containing Au as a main component is formed on the surface of the cap layer 10, the GaAs substrate 1 is etched to about 100 μm by mechanical polishing and chemical etching, and Au is also mainly added to the GaAs substrate 1 side. The electrode 12 as a component was formed. About 6 semiconductor wafers thus obtained
The cleavage was performed in the shape of a bar at intervals of 00 μm. FIG. 3A shows the sectional shape of the semiconductor laser device at this stage. Next, the single quantum well active layer 22 exposed on the cleaved surface of this bar was etched by an ammonia-based etching solution by about 150 nm. At this time, the GaInP clad layers 21 and 23
Is hardly etched by the ammonia-based etching solution, so that the active layer 22 has a recessed shape as shown in the partially enlarged view of FIG. Al on the front end face of this element
_An antireflection coating 13 of ₂ O ₃ (reflectance 5%) and a high reflection coating 14 (reflectance 90%) composed of amorphous Si / Al ₂ O ₃ were applied to the rear end face.

The semiconductor laser of this example could be stably operated at 70 ° C. and an optical output of 150 mW for 10,000 hours or more.

<Embodiment 4> FIG. 4 is a diagram showing the cross-sectional structure of a semiconductor laser device in a fourth embodiment of the semiconductor laser device according to the present invention. The first to third embodiments described above are cases where the active layer is etched with an etchant having a strong selectivity, but in the present embodiment, the ammonia-based etching in which the selection ratio of the etching rates of the active layer and the clad layer is about several times. This is the case when a liquid is used. In this case, since the selection ratio is small,
Not only the active layer but also the cladding layer is etched to form a recess having a shape as shown in the figure. Such depressions are also formed by reverse sputtering performed prior to the formation of the end face reflection film. Even in the shape where the selective etching was incomplete, the light output was improved by about 30 to 40%. Although the effect of protecting the end face of such a shape is smaller than that in the case where only the active layer is etched, it has an advantage that the range of etching time for obtaining good characteristics is wide and the process is easy.

<Embodiment 5> FIG. 8 is a diagram showing a sectional structure of a semiconductor laser device in a fifth embodiment of the semiconductor laser device according to the present invention. The manufacturing process of the semiconductor laser is the same as that of the first embodiment, and Al ₂ O is formed by sputtering after element formation.
_{3 A} film is formed on the end face. At this time, if the sputtering energy and the flow rate of Ar gas are appropriately set, the Al ₂ O ₃ film 13 does not adhere to the inside of the groove of the active layer 3 and the void 51 remains. Such an end face protective film is effective in increasing the output of the semiconductor laser due to the function of chemically protecting the laser end face and the function of controlling the end face reflectance, but the stress between the face film and the semiconductor reduces the reliability. There is also the drawback of inviting. In the case of this structure, the Al ₂ O ₃ film shields the semiconductor surface from the outside air but is not physically in contact with the active layer surface, so that the problem of the end face protective film as described above can be solved. In addition, in the present embodiment, when an organic acid is used for etching the active layer and the bottom surface of the active layer is the (111) plane 52 as shown in the figure, the chemical stability of the (111) plane results in a larger end face protection effect. There is. In addition, (N
H ₄ ) ₂ S, (NH ₄ ) ₂ Se, (NH ₄ ) ₂ Te are added, or after selective etching, surface treatment with (NH ₃ ) S _X is performed to reduce the active layer bottom surface to V
It is also effective to protect with the group I element 53.

<Embodiment 6> FIG. 9 is a view showing a semiconductor laser device in a sixth embodiment of the semiconductor laser device according to the present invention. This example is the same as the Al in the fifth example.
_This is an example in which the element structure is improved in order to more completely shield the ₂ O ₃ film 13 from the outside air. In the structure of the fifth embodiment, the groove-like structure is formed on the end face of the element by etching the active layer. When the protective film is covered on this groove, gas can be prevented from entering from the film surface, but gas is introduced from the side hole formed when the semiconductor laser is chipped, and the gas is not blocked. Perfect. In order to solve this problem, in this embodiment, a step as shown in FIG. 9 is formed in a region near the end face about 50 μm away from the laser stripe of the substrate before crystal growth.
601 is provided, and crystal growth similar to that of the first embodiment is performed on this substrate. At this time, since the active layer is discontinuous at the edge of the recess of the substrate as shown in FIG. 12, the groove formed by the active layer etching is also discontinued at this portion, so that outside air may enter the active layer in the stripe portion during chip separation. It becomes possible to completely shut off the gas.

<Embodiment 7> FIG. 10 is a diagram showing a semiconductor laser device in a seventh embodiment of the semiconductor laser device according to the present invention. In this structure, the optical guide layer is left in the active layer removed region in order to overcome the defect that the characteristics are deteriorated when the etching is too deep and the optical waveguide cannot be performed in the active layer removed region. In this structure, first, n on the n-GaAs substrate 101
-(Al _0.7 Ga _0.3 ) _0.5 In _0.5 P Cladding layer 201, n-Ga _0.9 In _0.1 A
s _0.8 P _0.2 optical guide layer 701, multiple quantum well active layer 302, p-G
a _0.9 In _0.1 As _0.8 P _0.2 Optical guide layer 702, p- (Al _0.7 Ga _0.3 ) _0.5
In _0.5 P clad layer 203, p-Ga _0.5 In _0.5 P contact layer 204
Were sequentially grown. The multi-quantum well active layer 302 is Ga _0.8 In
It is formed by a _0.2 As well layer 304 and a GaAs barrier layer 703. Next, a stripe-shaped SiO ₂ film is formed on this structure by using a thermal CVD method and a photolithographic technique. This Si
Using the O ₂ film as a mask, p-Ga _0.5 In _0.5 P contact layer 204 and
p- (Al _0.7 Ga _0.3 ) _0.5 In _0.5 P After etching a part of the cladding layer 203, n-Ga _0.5 In _0.5 P was formed by metalorganic vapor phase epitaxy.
The block layer 306 was selectively grown in the region without the SiO ₂ film. For the series resistance reduction of the element, after removing the SiO ₂ film p-
A GaAs cap layer 110 was formed. Next, A on the surface of the wafer
An electrode 111 containing u as a main component was formed, the GaAs substrate was etched to about 100 μm by mechanical polishing and chemical etching, and an electrode 112 containing Au as a main component was also formed on the GaAs substrate side.

Such a semiconductor wafer was cleaved in a bar shape at intervals of about 600 μm. Next, the multiple quantum well active layer 302 exposed on the cleavage plane of this bar was etched by about 300 nm with a sulfuric acid-based etching solution. At this time, the crystal containing phosphorus is hardly etched by the sulfuric acid-based etching solution, so that the active layer portion is dented and the optical guide layer remains. The etchant used here is, for example, H ₂ SO ₄ : H ₂ O ₂ : H ₂ O = 1: 2: 50, and the etching time is about 10 seconds.

In the case of the structures of Examples 1 to 6, such deep active layer etching caused deterioration of the device characteristics, but in the case of this structure, since the waveguide function due to the remaining optical guide layer remains, deeper etching is performed. It becomes possible to obtain a larger effect. An Al ₂ O ₃ anti-reflection coating 113 (reflectance 5%) is provided on the front end face of this element.
The rear end face of the device was provided with a high reflection coating 114 (reflectance 90%) composed of a-Si / Al ₂ O ₃ . The semiconductor laser of this embodiment has a light output of 150 mW at 70.degree.
It was possible to operate stably for more than 000 hours.

<Embodiment 8> As an eighth embodiment, instead of using a single InGaAsP layer as the optical guide layer in the structure of the seventh embodiment, InGaAsP layer 801 and GaAs as shown in FIG. 11 are used.
An example of a multilayer structure of the layer 802 is shown. In this structure, I
The thickness of the nGaAsP layer is 10 nm, and the thickness of the GaAs layer becomes thin as 10 nm, 6 nm, and 3 nm as the distance from the active layer increases. By etching the GaAs layer of the optical guide layer having such a structure, the end face of the semiconductor laser can be made to have a lens effect, and the beam emission shape of the semiconductor laser can be narrowed. .

<Embodiment 9> As a ninth embodiment of the present invention, a structure in which an end face is formed by using a reactive ion etching method instead of cleavage in a semiconductor crystal having a structure similar to that of the seventh embodiment of the present invention was produced. . In this structure, since the laser light is guided not only in the active layer but also in the entire light guide layer, it is possible to limit the spread of light in the cladding layer while keeping the optical confinement in the active layer at an appropriate value. For this reason, there are no problems such as the deviation of the tilt angle of the end face from the vertical and the deterioration of the reflecting surface function due to the unevenness of the end face, which are often problems when the end face of the conventional semiconductor laser is formed by reactive ion etching or chemical etching. A semiconductor laser with initial characteristics can be obtained. However, even in such a structure, it was difficult to obtain good reliability due to the roughness of the surface of the end face portion. In the present invention, the active layer etching was further performed on such a structure with a sulfuric acid-based etching solution, and the reliability of this device could be improved to 10,000 hours or more at 100 ° C. and 100 mW operation.

<Embodiment 10> FIG. 12 is a diagram showing a semiconductor laser device in a tenth embodiment of a semiconductor laser device according to the present invention. This embodiment shows an example in which the present invention is applied to a semiconductor laser composed of II-VI group semiconductors. In this structure, first, n-Mg _0.1 Zn _0.9 S is formed on the n-GaAs substrate 101.
_0.14 Se _0.86 Clad layer 901, Single quantum well active layer 902, p-
Mg _0.1 Zn _0.9 S _0.14 Se _0.86 Clad layer 903, p-ZnSe _0.5 Te _0.5
The contact layer 904 was sequentially crystal-grown. The single quantum well active layer 902 is formed by sandwiching a Cd _0.3 Zn _0.7 Se well layer 905 with a ZnS _0.07 Se _0.93 guide layer 906. Next, a stripe-shaped SiO ₂ film is formed on this structure by using a thermal CVD method and a photolithographic technique. Using this SiO ₂ film as a mask, p-Zn
Se _0.5 Te _0.5 Contact layer 904 and p-Mg _0.1 Zn _0.9 S _0.14 Se
After etching a part of the _0.86 clad layer 903, an n-Mg _0.3 Zn _0.7 S _0.35 Se _0.65 block layer 907 was selectively grown in a region without a SiO ₂ film by a metal organic chemical vapor deposition method. To reduce the series resistance of the device, after removing the SiO ₂ film, p-ZnSe _0.5 Te
_{A 0.5} buried layer 908 was formed. Next, an electrode 111 containing Au as a main component is formed on the surface of the wafer, and the GaAs substrate is etched to about 100 μm by mechanical polishing and chemical etching.
The electrode 112 containing Au as a main component was also formed on the GaAs substrate side.
Such a semiconductor wafer was cleaved in a bar shape at intervals of about 600 μm. FIG. 12A shows the sectional shape of the semiconductor laser at this stage. Next, the single quantum well active layer 902 exposed on the cleaved surface of this bar was etched by a chromic acid-based etching solution by about 150 nm. At this time, since the MgZnSSe clad layer is not etched by the hydrochloric acid-based etching solution, the active layer portion has a dented shape as shown in FIG. 12B. An Al ₂ O ₃ antireflection coating 113 (reflectance: 5%) was applied to the front end face of this element, and a-Si / Al was applied to the rear end face of the element.
₂ O ₃ by configured high reflection co - coating 114 (reflectance 9
0%), a semiconductor laser capable of operating stably for 10000 hours or more at 70 ° C. optical output of 20 mW was obtained.

The present invention is not limited to the above embodiment. For example, although the above embodiment shows the case where the light emitting end face is one, the light may be emitted from both faces.

[0036]

According to the present invention, the optical output of a semiconductor laser can be increased by 30% to 100% simply by adding a chemical etching step to the conventional manufacturing process of a high power semiconductor laser.

[Brief description of drawings]

FIG. 1 is a diagram showing the structure of a first embodiment of a semiconductor laser according to the present invention.

FIG. 2 is a diagram showing the structure of a third embodiment of a semiconductor laser according to the present invention.

FIG. 3 is a diagram showing the structure of a third embodiment of a semiconductor laser according to the present invention.

FIG. 4 is a diagram showing the structure of a fourth embodiment of the semiconductor laser according to the present invention.

FIG. 5 is a perspective view showing the structure of a conventional semiconductor laser.

FIG. 6 is a conceptual diagram of temperature distribution in an end face region.

FIG. 7 shows the relationship between the etching depth and the light output at the end surface destruction.

FIG. 8 shows a semiconductor laser structure according to a fifth embodiment of the present invention.

FIG. 9 shows a semiconductor laser structure according to a sixth embodiment of the present invention.

FIG. 10 shows a semiconductor laser structure according to a seventh embodiment of the present invention.

FIG. 11 shows a semiconductor laser structure according to an eighth embodiment of the present invention.

FIG. 12 shows a semiconductor laser structure according to a tenth embodiment of the present invention.

[Explanation of symbols]

1: GaAs substrate 17: clad layer 2: clad layer 18: contact layer 3: multiple quantum well active layer 19: well layer 4: clad layer 20: barrier layer 5: contact layer 21: clad layer 6: well layer 22: single Single quantum well active layer 7: Barrier layer 23: Guide layer 8: Block layer 24: Well layer 9: Buried layer 25: GaAs barrier layer 10: Cap layer 26: GaAs substrate 11: Surface electrode 27: Block layer 12: Substrate Side electrode 28: Clad layer 13: Antireflection coating 29: Active layer 14: Coating 30: Clad layer 15: Clad layer 31: Cap layer 16: Multiple quantum well active layer

Front page continuation (72) Inventor Satoru Kikuchi 15 Asahidai, Moroyama-cho, Iruma-gun, Saitama Hitachi Eastern Semiconductor Co., Ltd.

Claims (11)

[Claims] 1. A semiconductor laser device having two clad layers formed of a semiconductor crystal and an active layer sandwiched between the two clad layers, wherein a laser beam is emitted from an end face of the crystal when energized. A semiconductor laser device, wherein the active layer is recessed inside the crystal at an end face of the crystal for emitting the laser light. 2. A semiconductor device comprising two clad layers formed of a semiconductor crystal and an active layer sandwiched between the two clad layers,
A semiconductor laser device that emits a laser beam from an end face of a crystal when energized, wherein a portion of the end face of the crystal that emits the laser beam adjacent to the active layer and the two clad layers is inside the crystal. A semiconductor laser device characterized by being recessed. 3. The semiconductor laser device according to claim 1, wherein a group VI element is attached to the surface of the recess of the active layer. 4. The semiconductor laser device according to claim 1, wherein the depth of the recess of the active layer is larger than the thickness of the active layer, and the function of the end face as a reflector is lost. A semiconductor laser device characterized by being set in a predetermined range. 5. The semiconductor laser device according to claim 1, wherein the bottom surface of the recess is a (111) plane. 6. The semiconductor laser device according to claim 1, wherein when the protective film made of an insulating material is provided on the end face of the semiconductor laser device, the active layer in the recess is in direct contact with the protective film. Semiconductor laser characterized by not
The device. 7. The semiconductor laser device according to claim 1, further comprising an optical guide layer between the active layer and the clad layer, the optical guide layer being formed by removing the active layer in a cross section. A semiconductor laser device characterized in that it remains even in the exposed portion. 8. A method for manufacturing a semiconductor laser having two clad layers formed of a semiconductor crystal and an active layer made of a semiconductor crystal sandwiched between the two clad layers, the method comprising: A method of manufacturing a semiconductor laser device, comprising the steps of: after forming a wafer having layers, cleaving it into a bar shape and selectively etching the cleaved surface of the active layer. 9. The method for manufacturing a semiconductor laser device according to claim 8, wherein the two cladding layers are AlGaAs and the active layer is a multiple quantum well layer having GaAs as a well layer, and used as an etching solution in the etching step. A method for manufacturing a semiconductor laser device, which comprises using an ammonia-based etching solution. 10. The method of manufacturing a semiconductor laser device according to claim 9, wherein the two cladding layers are GaInP and the active layer is a single well layer of GaInAs sandwiched by a guide layer of GaAs, and the etching is performed. A method of manufacturing a semiconductor laser device, wherein an ammonia-based etching solution is used as an etching solution in the step. 11. The method of manufacturing a semiconductor laser device according to claim 8, wherein the two cladding layers are AlGaInP.
2. A method for producing a semiconductor laser device, wherein the active layer is a multiple quantum well layer having GaInP as a well layer, and a hydrochloric acid-based etching solution is used as an etching solution in the etching step.