JPH1065262A - Manufacture of semiconductor laser - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing a semiconductor laser, which can increase the output of the laser and increase the reliability of the laser. SOLUTION: First, an N-type clad layer 4 is formed on the upper surface 18 of an N-type substrate 3. Then, an active layer 5 is formed on the layer 4. After that, a P-type clad layer 6 is formed on the layer 5. Then, a P-type contact layer 8 is formed on the layer 6. After that, a laser beam 15 is irradiated on an emitting surface 12, consisting of the end surface of the layer 5, whereby impurities adhering to the emitting surface 12 are removed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a semiconductor laser, and more particularly, to a method for manufacturing a semiconductor laser that absorbs less light at an end of an element.

[0002]

2. Description of the Related Art At present, semiconductor lasers are incorporated in various devices such as laser printers, laser gyroscopes and laser Doppler velocimeters. It is also widely used for laser isotope separation, which enriches uranium using laser light, and laser-induced chemical reaction, in which molecules are excited by laser light to cause a chemical reaction.

In order to increase the reliability and output of these devices, it is necessary to increase the output and reliability of the semiconductor laser as the light source.

In general, a semiconductor laser includes a p-type cladding layer, an active layer formed on the p-type cladding layer,
A laser beam is generated by passing a current through an n-type cladding layer formed on the active layer. In such a semiconductor laser, it is generally known that the forbidden band width (band gap) is reduced on the end face of the active layer, that is, on the surface from which light is emitted. The first cause of this is that lattice defects and the like are likely to occur on the end face, and thus surface recombination is likely to occur. Second, impurities are attached to the end face, and oxygen molecules in the air enter the end face to form gallium oxide or the like for reducing the forbidden band width.

Here, when the forbidden band width of the end face becomes small,
The laser light generated inside the active layer is easily absorbed at the end face. Therefore, there is a problem that the output of the semiconductor laser is reduced. In addition, when light generated inside the active layer is absorbed by the end face, the temperature of the end face rises, and in the worst case, the end face is melted, thereby lowering the reliability of the semiconductor laser.

Therefore, in order to increase the output and the reliability of the semiconductor laser, it is necessary to prevent such light absorption at the end face.

Here, as a semiconductor laser with little light absorption at the end face, the one described in JP-A-64-81387 is known.

FIG. 9 is a schematic perspective view showing a conventional semiconductor laser as described in the above publication. Referring to FIG. 9, semiconductor laser 101 includes electrodes 102 and 109.
, An n-type substrate 103, an n-type cladding layer 104, an active layer 105, a p-type cladding layer 106, an n-type block layer 107, a p-type contact layer 108, and passivation films 110 and 111. I have.

The electrode 10 is placed in contact with the n-type substrate 103.
2 are formed. An n-type cladding layer 104 is formed on an n-type substrate 103 so as to be in contact therewith. The active layer 105 is formed on the n-type cladding layer 104 so as to be in contact therewith. The p-type cladding layer 106 is formed on the active layer 105 so as to be in contact therewith. An n-type block layer 107 is formed on p-type cladding layer 106 so as to be in contact therewith. The p-type contact layer 108 is formed so as to be in contact with the n-type block layer 107. The p-type contact layer 108 is formed so as to be in contact with the p-type cladding layer 106 at the center. The electrode 109 is a p-type contact layer 108
Is formed so as to be in contact with.

An n-type cladding layer 104 and an active layer 105
And a stripe-shaped light-emitting region 114 where light is generated is formed at the center of the p-type cladding layer 106. This stripe-shaped light emitting region 114 is formed on the p-type contact layer 108.
And is located below the surface where the p-type cladding layer 106 is in contact and extends in the upper right direction in the figure.

A portion of the light emitting surface 112 which is to be an end surface of the stripe-shaped light emitting region 114 (a portion surrounded by a dotted line in the drawing).
The light is emitted from. Passivation film 110 is formed to cover emission surface 112. Also, the rear section 113
Is formed to cover.
In the active layer 105, the forbidden band width increases as approaching the emission surface 112.

Next, a method of manufacturing the conventional semiconductor laser shown in FIG. 9 will be described. FIG. 10 is a schematic perspective view showing a method for manufacturing the semiconductor laser shown in FIG. FIG.
, An n-type cladding layer 104 is formed on an n-type substrate 103 by a molecular beam epitaxy method or the like. next,
The active layer 105 is formed on the n-type
A p-type cladding layer 106 is sequentially grown on the layer 5 by a molecular beam epitaxial method or the like.

Next, an n-type substance is formed on the p-type cladding layer 106, and a central portion of the n-type substance is etched in a stripe shape to form an n-type block layer 107.
At this time, the p-type cladding layer 106 is exposed in a stripe shape. Next, a p-type contact layer 108 is formed by molecular beam epitaxy or the like so as to be in contact with the p-type cladding layer 106 and the n-type block layer 107.

Next, the electrodes 102 and 109 are formed by a vapor deposition method. Next, the wafer is cut out from the wafer by the cleavage method in units of elements, and the cleavage plane is formed on the emission surface 112 and the rear end surface 11.
3 is assumed. The p-type cladding layer 106 and the active layer 10
5 and the n-type cladding layer 104, the portion located below the surface where the p-type contact layer 108 and the p-type cladding layer 106 are in contact is the stripe-shaped light emitting region 114.

Next, the active layer 105, the n-type cladding layer 104, and the p-type cladding layer 106 are mixed by irradiating a laser beam to the stripe-shaped light emitting region 114 and its peripheral portion of the emission surface 112. By such laser beam irradiation, aluminum in the n-type cladding layer 104 and the p-type cladding layer 106 enters the active layer 105.
Therefore, near the end face of the active layer 105, that is, near the end face of the stripe-shaped light emitting region 114, the forbidden band width is widened.

Referring to FIG. 9, passivation film 1 is formed on rear end face 113 and emission face 112 irradiated with laser light.
11 and 110 are formed. Thus, the semiconductor laser 101 is completed.

In the semiconductor laser manufactured as described above, as shown in FIG. 10, by mixing aluminum atoms in the n-type cladding layer 104 and the p-type cladding layer 106 into the active layer 105, the active layer 105 is formed. , The forbidden band width of the end face can be increased, and light absorption at the end face can be prevented. Therefore, the output of the semiconductor laser can be improved, and further, the reliability can be improved.

[0018]

However, the conventional semiconductor laser shown in FIG. 9 has the following problems.

First, another cause for reducing the forbidden band width of the active layer, that is, a decrease in the forbidden band width due to the entry of oxygen atoms into the end face or the attachment of impurities to the end face is described below. , No measures have been taken. Therefore, the semiconductor laser shown in FIG. 10 has a problem that the forbidden band width at the end face cannot be sufficiently widened.

Further, in the conventional semiconductor laser,
As is apparent from FIG. 10, aluminum atoms mixed into the active layer 105 are contained in the n-type cladding layer 104 and the p-type cladding layer 106. Where n
Aluminum contained in the p-type cladding layer 104 and the p-type cladding layer 106 is very small,
Cannot supply aluminum sufficiently, so that the forbidden band width of the active layer 105 cannot be sufficiently widened.

Therefore, the present invention has been made to solve the above-described problem, and it is intended to remove oxygen and impurities on the end face of a semiconductor laser and supply sufficient aluminum to the active layer to thereby remove the active layer. It is an object of the present invention to provide a method of manufacturing a semiconductor laser capable of widening the forbidden band width.

[0022]

A method of manufacturing a semiconductor laser according to one aspect of the present invention includes the following steps.

I containing a first element selected from Group III of the periodic table and a second element selected from Group V of the periodic table
A first surface and a first surface formed of a II-V compound semiconductor;
Preparing a substrate of the first conductivity type having a second surface opposite to the surface of the first conductivity type. Here, Group III of the periodic table includes boron (B), aluminum (Al), gallium (Ga), indium (In), and thallium (Tl). Group V of the periodic table includes nitrogen (N), phosphorus (P), arsenic (A
s), antimony (Sb), and bismuth (Bi).

Forming a first electrode layer on the second surface of the substrate; Forming a first conductivity type cladding layer including a first element, a second element, and a third element different from the first element selected from the group III on the first surface of the substrate; .

A step of forming an active layer containing a first element, a second element, and a third element on the first conductivity type cladding layer;

A step of forming a second conductivity type cladding layer including the first element, the second element, and the third element on the active layer.

Forming a second conductivity type contact layer made of a group III-V compound semiconductor containing the first element and the second element on the second conductivity type cladding layer;

Forming a second electrode layer on the contact layer; A step of irradiating a laser beam on an emission surface formed of an end surface of the active layer to remove impurities attached to the emission surface.

A step of forming a protective film on the emission surface irradiated with the laser beam. Here, it is preferable that the first element is gallium, the second element is arsenic, and the third element is aluminum.

In the method of manufacturing a semiconductor laser having the above-described structure, in the step shown in the figure, the emission surface is irradiated with a laser beam to remove impurities attached to the emission surface. No impurities for reducing the forbidden band width (band gap) are attached. Therefore, the forbidden band width is not reduced on the end face of the active layer, and light is not absorbed on the end face of the active layer. Therefore, the output of the light emitted from the end face of the active layer is increased, and the end face of the active layer does not generate heat, so that the reliability can be improved.

A method of manufacturing a semiconductor laser according to another aspect of the present invention includes the following steps.

I containing the first element selected from group III of the periodic table and the second element selected from group V of the periodic table
A first surface and a first surface formed of a II-V compound semiconductor;
Preparing a substrate of the first conductivity type having a second surface opposite to the surface of the first conductivity type.

Forming a first electrode layer on the second surface of the substrate; Forming a first conductivity type cladding layer including a first element, a second element, and a third element different from the first element selected from the group III on the first surface of the substrate; .

Forming an active layer containing a first element, a second element, and a third element on the first conductivity type cladding layer;

A step of forming a second conductivity type clad layer including the first element, the second element, and the third element on the active layer.

Forming a second conductivity type contact layer made of a III-V compound semiconductor containing a first element and a second element on the second conductivity type cladding layer;

A step of forming a second electrode layer on the contact layer. A step of forming a film made of a third element on an emission surface formed by an end face of the active layer, thereby incorporating oxygen attached to the emission surface into the film made of the third element.

A step of forming a protective film on the emission surface on which the film made of the third element is formed. Here, it is preferable that the first element is gallium, the second element is arsenic, and the third element is aluminum.

In the method of manufacturing a semiconductor laser having such steps, in the step indicated by (3), the third
Oxygen adhering to the emission surface by forming a film made of the element is taken into the film made of the third element, so that oxygen does not adhere to the emission surface. Therefore, an oxide that reduces the forbidden band width is not formed on the emission surface, so that the forbidden band width of the active layer is not reduced on the emission surface. Therefore, light is not absorbed at the end face of the active layer.
As a result, the output of the semiconductor laser can be increased, heat generation at the end face can be prevented, and reliability can be improved.

A method of manufacturing a semiconductor laser according to still another aspect of the present invention includes the following steps.

I containing the first element selected from Group III of the periodic table and the second element selected from Group V of the periodic table
A first surface and a first surface formed of a II-V compound semiconductor;
Preparing a substrate of the first conductivity type having a second surface opposite to the surface of the first conductivity type.

A step of forming a first electrode layer on the second surface of the substrate. Forming a first conductivity type cladding layer including a first element, a second element, and a third element different from the first element selected from the group III on the first surface of the substrate; .

Forming an active layer containing a first element, a second element and a third element on the first conductivity type cladding layer;

A step of forming a second conductivity type clad layer including the first element, the second element, and the third element on the active layer.

A step of forming a second conductivity type contact layer made of a group III-V compound semiconductor containing a first element and a second element on the second conductivity type cladding layer;

A step of forming a second electrode layer on the contact layer. A step of forming a film made of a third element on an emission surface formed by an end face of the active layer.

A step of increasing the forbidden band width of the active layer by melting the film made of the third element to mix the third element into the active layer.

Here, in the step of increasing the forbidden band width of the active layer, it is preferable that the film made of the third element is melted by irradiating the film made of the third element with a laser beam.

In the step of increasing the forbidden band width of the active layer, a current is caused to flow through the active layer to generate a laser beam from the active layer, and the laser beam is applied to the film made of the third element. It is preferable to include melting the film made of the third element by the following method.

Furthermore, it is preferable that the first element is gallium, the second element is arsenic, and the third element is aluminum.

In the method of manufacturing a semiconductor laser having such a step, in the step indicated by (3), the film made of the third element is melted, and the third element is mixed into the active layer to form an end face of the active layer. Increase the forbidden band width. for that reason,
Since the third element is contained more in the film made of the third element than in the cladding layer, more third elements are activated than in the case where the third element in the cladding layer is mixed into the active layer. Can be mixed into the layers. Therefore, the forbidden band width at the end face of the active layer can be made sufficiently large. Therefore, light is not absorbed at the end face of the active layer. As a result, it is possible to increase the output of the semiconductor laser, prevent heat generation at the end face, and improve the reliability.

When the film made of the third element is melted by irradiating the film made of the third element with a laser beam, and the third element is mixed into the active layer, the third element is removed. It can be surely mixed into the active layer.

When a current is applied to the active layer to generate a laser beam from the active layer and the laser beam is applied to the film made of the third element to melt the film made of the third element, Element can be reliably mixed into the active layer.

[0054]

BEST MODE FOR CARRYING OUT THE INVENTION

(First Embodiment) FIG. 1 is a schematic perspective view showing a semiconductor laser according to a first embodiment of the present invention. Referring to FIG. 1, a semiconductor laser 1 includes an n-type substrate 3, an n-type cladding layer 4, an active layer 5, a p-type cladding layer 6, an n-type block layer 7, and a p-type contact layer 8. , Electrodes 2, 9;
And passivation films 10 and 11.

The n-type cladding layer 4 is formed on the upper surface 18 of the n-type substrate 3.
Are formed. The electrode 2 is in contact with the lower surface 19 of the substrate 3. The material of the n-type substrate 3 is a GaAs compound semiconductor. The material of the electrode 2 is AuGe / Ni. The material of the n-type cladding layer 4 is an AlGaAs compound. The active layer 5 is formed on the n-type cladding layer 4 so as to be in contact therewith. The material of the active layer 5 is an AlGaAs compound. The p-type cladding layer 6 is formed on the active layer 5 so as to be in contact therewith. p
The material of the mold cladding layer 6 is an AlGaAs compound. p
An n-type block layer 7 is formed on the mold clad layer 6 so as to be in contact therewith. The material of the n-type block layer 7 is a GaAs compound. A groove is formed at the center of the n-type block layer 7. The p-type contact layer 8 is formed so as to be in contact with both the n-type block layer 7 and the p-type cladding layer 6. p
The material of the mold contact layer 8 is a GaAs compound semiconductor.

The electrode 9 is formed on the p-type contact layer 8 so as to be in contact therewith. The material of the electrode 9 is Au / AuZn. The ratio of Al in the active layer 5 is smaller than the ratio of Al in the n-type cladding layer 4 and the p-type cladding layer 6. Further, laser light is generated from the stripe-shaped light emitting region 14 surrounded by a dotted line in the drawing. The stripe-shaped light emitting region 14 includes the n-type cladding layer 4, the active layer 5, and the p-type cladding layer 6, and is formed below a surface where the p-type cladding layer 6 and the p-type contact layer 8 are in contact.

The passivation film 10 is formed on the light exit surface 12. The passivation film 10 includes a Si film,
It is a multilayer film composed of a SiO ₂ film. The passivation film 10 is substantially transparent. The passivation film 11 is in contact with the rear end face 13. Passivation film 1
1 also has a multilayer structure of a SiO ₂ film and a Si film, but is thicker than the passivation film 10.

Next, a method of manufacturing the semiconductor laser shown in FIG. 1 will be described. FIG. 2 is a schematic perspective view showing a first step of the method for manufacturing the semiconductor laser shown in FIG. FIG.
, An n-type substrate 3 made of a GaAs compound semiconductor
About 0.7 mm thick made of an AlGaAs compound
MOCVD (Metal Organic)
Chemical Vapor Deposition).

Next, AlGaAs is formed on the n-type cladding layer 4.
The active layer 5 having a thickness of about 0.7 μm made of
It is formed by the VD method. On the active layer 5, a p-type cladding layer 6 of about 0.7 μm
It is formed by a CVD method. Here, the proportion of Al in the active layer 5 is smaller than the proportion of Al in the n-type cladding layer 4 and the p-type cladding layer 6.

A GaAs compound is formed on the p-type cladding layer 6 to a thickness of about 0.6 μm, and this GaAs compound is selectively etched to selectively expose the surface of the p-type cladding layer 6. Thus, an n-type block layer 7 is formed. The depth of the groove is about 0.7 μm. p-type cladding layer 6
And a p-type contact layer 8 made of a GaAs compound semiconductor is formed by MOCVD so as to be in contact with the n-type block layer 7. The lower surface 19 of the substrate 3 is polished.

Next, the lower surface 19 of the substrate 3 is
Next, an electrode 2 made of AuGe / Ni is formed. Also,
An electrode 9 made of Au / AuZn is formed on the p-type contact layer 8 by a vapor deposition method.

Next, the emission surface 12 and the rear end surface 13 are formed by cleavage. The distance between the exit surface 12 and the rear end surface 13 is about 300 μm.

Referring to FIG. 3, an Ar laser shown by arrow 15 is applied to emission surface 12 and rear end surface 13 in a vacuum or a hydrogen atmosphere, and the temperature of emission surface 12 and rear end surface 13 is set to 200 to 300 ° C. And Thereby, the emission surface 1
2 and the impurities and oxides attached to the rear end face 13 are volatilized.

Referring to FIG. 1, a passivation film 10 is formed by laminating a Si film and a SiO ₂ film on the emission surface 12 irradiated with the laser beam by the CVD method. Next, a Si film and a SiO ₂ film are stacked on the rear end face 13 to form a passivation film 11. The thickness of the passivation film 10 is about 0.4 μm, and the reflectance is 3%. Further, the thickness of the passivation film 11 is 0.8 μm, and the reflectance is 90%.

In the method of manufacturing a semiconductor laser according to the present invention thus configured, the steps shown in FIG.
Since the emission surface 12 and the rear end face 13 are irradiated with an Ar laser indicated by an arrow 15, impurities and oxides attached to the output face 12 and the rear end face 13 are volatilized. For this reason, there is no decrease in the forbidden band width due to impurities or oxides, which was not considered in the prior art, and the forbidden band width does not become small at the end face of the semiconductor laser. Therefore, light is not absorbed at the end face of the active layer. As a result, the output of the semiconductor laser can be increased, heat generation at the end face can be prevented, and reliability can be improved.

(Embodiment 2) FIG. 4 is a schematic perspective view showing a semiconductor laser according to Embodiment 2 of the present invention. Referring to FIG. 4, semiconductor laser 21 includes electrode 2
2, 29, an n-type substrate 23, an n-type cladding layer 24,
An active layer 25, a p-type cladding layer 26, an n-type block layer 27, a p-type contact layer 28, passivation films 30, 31 and an aluminum film 36 are provided.

The semiconductor laser 21 shown in FIG. 4 has substantially the same structure as the semiconductor laser 1 shown in FIG. for that reason,
The electrode 22, the n-type substrate 23, and the n-type cladding layer 2 in FIG.
4, an active layer 25, a p-type cladding layer 26, an n-type block layer 27, a p-type contact layer 28, an electrode 29, passivation films 30, 31, an emission surface 32, a rear end surface 33, a stripe light emitting region 34, an upper surface 38, The lower surface 39 is the same as the one having the same name in FIG.

The only difference between the semiconductor laser 21 shown in FIG. 4 and the semiconductor laser 1 shown in FIG. 1 is that, in the semiconductor laser 21 shown in FIG. 4, the distance between the emission surface 32 and the passivation film 30 and the rear end surface 33 are different. Passivation film 3
1 in that an aluminum film 36 is formed.

Next, a method of manufacturing the semiconductor laser shown in FIG. 4 will be described. FIG. 5 is a schematic perspective view showing a method for manufacturing the semiconductor laser shown in FIG. Referring to FIG. 5, similarly to FIG. 2 in the first embodiment, n-type substrates 23, n
Type clad layer 24, active layer 25, p-type clad layer 26,
An n-type block layer 27, a p-type contact layer 28, and electrodes 9 and 2 are formed. Next, the emission surface 32 and the rear end surface 3
Third, an aluminum film 36 is formed to a thickness of about 7 nm by a sputtering method. Oxygen atoms forming gallium oxide and the like on the emission surface 32 and the rear end surface 33 are taken into the aluminum film 36 by the aluminum film 36 and become alumina.

Referring to FIG. 4, passivation films 30 and 31 are formed on emission surface 32 and rear end surface 33 on which aluminum film 36 is formed. As described above,
The semiconductor laser 21 is completed.

In the method of manufacturing a semiconductor laser having the above-described structure, in the step shown in FIG.
In addition, since the aluminum film 36 is formed on the rear end face 33, oxygen atoms forming gallium oxide or the like on the emission surface 32 and the rear end face 33 can be taken into the aluminum film 36 as alumina. Since alumina is a stable substance, oxygen atoms in alumina do not bond with gallium or the like. Therefore, it is possible to suppress a decrease in the forbidden band width due to the oxide that has not been considered in the related art. Therefore, the forbidden band width is not reduced at the end face of the active layer, and light absorption at the end face can be prevented. Therefore, it is possible to increase the laser output, prevent heat generation at the end face, and improve the reliability of the semiconductor laser.

(Embodiment 3) FIG. 6 is a schematic perspective view showing a semiconductor laser according to Embodiment 3 of the present invention. Referring to FIG. 6, a semiconductor laser 41 is
2, 49, an n-type substrate 43, an n-type cladding layer 44,
An active layer 45, a p-type cladding layer 46, an n-type block layer 47, a p-type contact layer 48, and passivation films 50 and 51 are provided.

The semiconductor laser 41 shown in FIG. 6 has substantially the same configuration as the semiconductor laser 21 shown in FIG. Therefore, the electrode 42, the n-type substrate 43, the n-type cladding layer 44, the active layer 45, the p-type cladding layer 46, the n-type block layer 47, the p-type contact layer 48, the electrode 49, the passivation films 50 and 51 in FIG. , Emission surface 52, rear end surface 53, stripe-shaped light emitting region 54, aluminum film 56, upper surface 5
8. The lower surface 59 is the same as the one having the same name in FIG.

The only difference between the semiconductor laser 41 shown in FIG. 6 and the semiconductor laser 21 shown in FIG. 4 is that in the semiconductor laser 41 shown in FIG. The active layer 25 shown in FIG.
It is larger than the forbidden band.

Next, a method of manufacturing the semiconductor laser shown in FIG. 6 will be described. 7 and 8 are schematic perspective views showing a method for manufacturing the semiconductor laser shown in FIG. FIG.
8 and FIG. 8, as shown in FIG. 2 of the first embodiment, n-type substrate 43, n-type cladding layer 44, active layer 45,
A p-type cladding layer 46, an n-type block layer 47, a p-type contact layer 48, electrodes 42 and 49, an emission surface 52, and a rear end surface 53 are formed. Next, the emission surface 52 and the rear end surface 5
3, an aluminum film 56 having a thickness of about 7 nm is formed by a sputtering method. Next, the emission surface 52 and the rear end surface 53 are irradiated with an Ar laser beam indicated by an arrow 55 to set the aluminum film 56, the emission surface 52, and the rear end surface 53 to 1000 ° C. or higher, thereby converting the aluminum in the aluminum film into the active layer 45. (FIG. 7). Also,
A high output laser beam 75 is generated between the electrodes 42 and 49 by applying a voltage 10 times or more that during normal laser oscillation, and the aluminum film 56 is irradiated with the laser beam 75, so that the aluminum film 56 52 and the rear end face 53 may be at a high temperature of 1000 ° C. or more (FIG. 8). As a result, the aluminum in the aluminum film 56 becomes active layer 4
Mix into 5. Therefore, the forbidden band width of the active layer 45 increases near the light exit surface 52 and the rear end surface 53.

Referring to FIG. 6, passivation films 50 and 5 similar to passivation film 10 in the first embodiment are provided.
1 is formed by a CVD method. Thus, the semiconductor laser 41 is completed.

In the method of manufacturing the semiconductor laser thus configured, the steps shown in FIGS.
The aluminum film 56 is melted, and the aluminum film 56 is melted.
The aluminum contained therein is mixed into the active layer 45. Therefore, compared to the case where aluminum in the n-type cladding layer 44 and the p-type cladding layer 46 is mixed into the active layer 45,
A lot of aluminum can be mixed into the active layer,
The forbidden band width at the emission surface 52 and the rear end surface 53 can be further increased.

In addition, since the aluminum film 56 is formed on the emission surface 52 and the rear end surface 53, oxygen atoms forming gallium oxide and the like on the emission surface 52 and the rear end surface 53 may be taken into the aluminum film 56 as alumina. As a result, the forbidden band width at the emission surface 52 and the rear end surface 53 can be further increased.

Therefore, light is not absorbed at the end face of the active layer. As a result, the output of the semiconductor laser can be increased, heat generation at the end face can be prevented, and reliability can be improved.

Although the present invention has been described above, the embodiments shown here can be variously modified. That is, the laser that irradiates the emission surface and the rear end surface of the semiconductor laser may be any laser such as an Ar laser, a He—Ne laser, and a carbon dioxide laser. The method of growing the p-type cladding layer or the like may be not only the MOCVD method but also a molecular beam epitaxial method, a liquid phase epitaxial method, or the like. In addition, although a GaAs compound semiconductor is shown as the n-type substrate, a well-known material such as InGaAsP may be used instead.

The embodiments disclosed this time are to be considered in all respects as illustrative and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

[0082]

According to the present invention, the output reliability of the semiconductor laser can be improved by removing oxides and impurities attached to the emission surface of the semiconductor laser.

Further, according to the present invention, the forbidden band width at the end face of the active layer of the semiconductor laser can be increased, and the output and reliability of the semiconductor laser can be improved.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view showing a semiconductor laser according to a first embodiment of the present invention.

FIG. 2 is a schematic perspective view showing a first step of the method for manufacturing the semiconductor laser shown in FIG.

FIG. 3 is a schematic perspective view showing a second step of the method for manufacturing the semiconductor laser shown in FIG.

FIG. 4 is a schematic perspective view showing a semiconductor laser according to a second embodiment of the present invention.

FIG. 5 is a schematic perspective view showing a method for manufacturing the semiconductor laser shown in FIG.

FIG. 6 is a schematic perspective view showing a semiconductor laser according to a third embodiment of the present invention.

FIG. 7 is a schematic perspective view showing a method for manufacturing the semiconductor laser shown in FIG.

8 is a schematic perspective view showing another method for manufacturing the semiconductor laser shown in FIG.

FIG. 9 is a schematic perspective view showing a conventional semiconductor laser.

10 is a schematic perspective view showing a method for manufacturing the semiconductor laser shown in FIG.

[Explanation of symbols]

1, 21, 41 semiconductor lasers, 2, 9, 22, 29,
42, 49 electrodes, 3, 23, 43 n-type substrate, 4, 2
4, 44 n-type cladding layers, 5, 25, 45 active layers,
6, 26, 46 p-type cladding layer, 8, 28, 48 p
Mold contact layer, 10, 30, 50 Passivation film, 12, 32, 52 Outgoing surface, 15, 55, 75 Laser beam, 18, 38, 58 Top surface, 19, 39, 59
Lower surface, 36, 56 Aluminum film.

Claims (8)

[Claims] 1. An element containing a first element selected from Group III of the periodic table and a second element selected from Group V of the periodic table.
Preparing a substrate of a first conductivity type, which is made of an IV compound semiconductor, and has a first surface and a second surface facing the first surface; Forming a first electrode layer; a first conductivity type including the first element, the second element, and a third element different from the first element selected from the group III. Forming a cladding layer on the first surface of the substrate; and an active layer containing the first element, the second element, and the third element on the first conductivity type cladding layer. Forming a second conductive type cladding layer including the first element, the second element, and the third element on the active layer; and forming the second conductive type clad layer on the active layer. Of a second conductivity type made of a group III-V compound semiconductor containing the first element and the second element on the cladding layer of A step of forming a tact layer, a step of forming a second electrode layer on the contact layer, and irradiating a laser beam on an emission surface formed from an end surface of the active layer, thereby forming impurities adhering to the emission surface. And a step of forming a protective film on the emission surface irradiated with the laser beam. 2. The method according to claim 1, wherein the first element is gallium, the second element is arsenic, and the third element is aluminum. 3. A composition comprising a first element selected from Group III of the periodic table and a second element selected from Group V of the periodic table.
A step of preparing a substrate of a first conductivity type, which is made of an IV group compound semiconductor and has a first surface and a second surface opposite to the first surface; Forming a first electrode layer; a first conductivity type including the first element, the second element, and a third element different from the first element selected from the group III. Forming a cladding layer on the first surface of the substrate; and an active layer containing the first element, the second element, and the third element on the first conductivity type cladding layer. Forming a second conductive type clad layer including the first element, the second element, and the third element on the active layer; and forming the second conductive type clad layer on the active layer. Of a second conductivity type made of a group III-V compound semiconductor containing the first element and the second element on the cladding layer of Forming a tact layer, forming a second electrode layer on the contact layer, and forming a film made of the third element on an emission surface formed by an end face of the active layer, A semiconductor comprising: a step of taking oxygen attached to an emission surface into a film made of the third element; and a step of forming a protective film on the emission surface on which the film made of the third element is formed. Laser manufacturing method. 4. The method according to claim 3, wherein the first element is gallium, the second element is arsenic, and the third element is aluminum. 5. II containing a first element selected from group III of the periodic table and a second element selected from group V of the periodic table
Preparing a substrate of a first conductivity type, which is made of an IV compound semiconductor, and has a first surface and a second surface facing the first surface; Forming a first electrode layer; a first conductivity type including the first element, the second element, and a third element different from the first element selected from the group III. Forming a cladding layer on the first surface of the substrate; and an active layer containing the first element, the second element, and the third element on the first conductivity type cladding layer. Forming a second conductive type cladding layer including the first element, the second element, and the third element on the active layer; and forming the second conductive type clad layer on the active layer. Of a second conductivity type made of a group III-V compound semiconductor containing the first element and the second element on the cladding layer of A step of forming a tact layer, a step of forming a second electrode layer on the contact layer, a step of forming a film made of the third element on an emission surface formed by an end face of the active layer, Melting the film made of a third element to mix the third element into the active layer to increase the forbidden band width of the active layer. 6. The step of increasing the forbidden band width of the active layer includes irradiating the film made of the third element with a laser beam to melt the film made of the third element. A method for manufacturing a semiconductor laser according to claim 5. 7. The step of increasing the forbidden band width of the active layer includes causing a current to flow through the active layer to generate a laser beam from the active layer, and the laser beam is applied to a film made of the third element. 6. The method for manufacturing a semiconductor laser according to claim 5, comprising melting the film made of the third element by irradiating the film. 8. The semiconductor laser according to claim 5, wherein said first element is gallium, said second element is arsenic, and said third element is aluminum. Manufacturing method.