JPH03224284A - Semiconductor laser device and manufacture thereof - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an AI GaAs-based edge-emitting semiconductor laser device and a manufacturing method thereof.

(Prior Art) Semiconductor laser devices such as AlGaAs-based semiconductor laser devices have been widely used as light sources for optical disk devices and the like. When a semiconductor laser device is used as a light source for a recordable write-once optical disk device or an erasable rewritable optical disk device, it is required to have high reliability even under a high optical output state of 40 to 50 mW. Ru. Furthermore, when used as an excitation light source for a solid-state laser device such as a YAG laser, a high output of 100 mW or more is required.

(Problem to be solved by the invention) However, in relatively high-output semiconductor laser devices that are currently in practical use, when comparing elements with the same structure, the reliability is inversely proportional to the fourth power of the optical output. has been reported. That is, it has been extremely difficult to increase optical output while maintaining high reliability.

The main cause of deterioration of semiconductor laser devices during high output operation is end face deterioration. This is because the light density is high at the light emitting end face, and therefore heat is generated locally at the end face. The mechanism of this heat generation will be explained with reference to FIGS. 11 and 12.

Figures 11 (a) and (b) schematically show the energy band structure near the surface caused by surface states that occur when the (110) plane of p-type and p-type GaAs is slightly oxidized, respectively. FIG. It can be seen that in both the p-type and p-type cases, majority carriers accumulate near the surface, forming a so-called accumulation layer l.

It is generally known that the surface states of semiconductors bend the energy band near the surface, and this bending forms the storage layer 1 as shown in FIGS. 11(a) and (b). In addition, as shown schematically in Figures 12(a) and (b), minority carriers gather near the surface and majority carriers are moved away from the surface, resulting in an inverted layer in which the conductivity type is locally reversed. 2 may be formed. Whether the accumulation layer l or the inversion layer 2 is formed is determined by the magnitude relationship between the surface state and the Fermi level of the semiconductor.
In this case, the accumulation layer 1 is formed in both p-type and p-type cases.

The electrons and holes trapped in the surface level Es are released in a short relaxation time, and their energy is released as heat. New electrons or holes are captured in the vacant surface levels, and the same process described above is repeated, and heat continues to be released.

While repeating the above process, the heat emitted from the surface states concentrates on the semiconductor end face, the forbidden band width of the energy band narrows due to the heat generation, and the number of minority carriers increases due to the absorption of light, and the surface states This will further increase heat generation. This process causes the temperature of the semiconductor surface to rise, even reaching the melting point, resulting in edge breakage.

In the case of GaAs, an accumulation layer is formed, but in other materials, for example AlGaAs, an inversion layer may also be formed. In this case, majority carriers are captured in the surface states, but end face destruction occurs through the same process as in the case of the accumulation layer. Further, in the case of a semiconductor laser device used in a high injection state, heat generation due to surface states has become a more serious problem.

As a method for preventing end face deterioration caused by the heat generation of the end face as described above, a structure in which a window region is formed near the end face has been proposed. This is to provide a region transparent to laser light near the end face, thereby eliminating light absorption at the end face and suppressing heat generation caused by light absorption.

However, in such a configuration, problems arise in that the process of forming the window region is extremely complicated and it is also extremely difficult to configure the waveguide near the end face.

Furthermore, M! using GaAs! Extend is aimed at improving the characteristics of the interface in the S structure.
ed Abstracts of the 20th
Conference on Solid 5tate
Devlces and Materials, To
Kyo, (1988) pp. 263-266 has a method proposed. This makes the surface of GaAs (
G in air by treatment with NH4)2S aqueous solution.
Remove the oxide film formed on the aA3 surface and replace it with Ga.
This is to attach S. Here, by forming a layer made of GaS, the surface states caused by the oxide film are reduced.

However, in particular, AlGaAs is used for the end face of the optical element.
Up to now, no attempt has been made to improve the end face of a semiconductor laser device by surface treatment as described above. This is because AI is a very active substance and its oxide film is considered to be stable and cannot be removed.

Therefore, an object of the present invention is to provide AlGaAs having a structure that can suppress the surface states caused by oxides at the light emitting end face and that prevents end face destruction even in a high output state.
An object of the present invention is to provide a system semiconductor laser device and a method for manufacturing the same.

(Means for Solving the Problems) A semiconductor laser device of the present invention is an edge-emitting type semiconductor laser device having an AlGaAs active layer and a protective film formed on an end facet, the semiconductor laser device having an AlGaAs active layer and a protective film formed on the end facet. A film containing sulfur is formed between the two, thereby achieving the above object.

Further, the protective film may be made of a low melting point material.

Further, the low melting point material may be MgF2, sio, 5402
, CaF2, NaF and ZnS.

The manufacturing method of the present invention has an A I GaAs active layer,
A method for manufacturing an edge-emitting semiconductor laser device in which a protective film is formed on the end facet includes the steps of treating the end facet with a solution containing sulfur, and then forming the protective film. , thereby achieving the above objective.

Further, the solution containing sulfur is a (NH4)2S stock solution,
It may be selected from the group consisting of (NHa)2sx stock solution, (NH4)2S aqueous solution, and (NWA)2Sx aqueous solution.

Further, when the sulfur concentration of the sulfur-containing solution is X mol/mole, the time for treating the end face with the sulfur-containing solution may be 1.5/X seconds or more.

Alternatively, the end face may be formed by cleaving the wafer in the solution containing sulfur, and then the end face may be treated with the solution.

Further, the protective film may be formed by a resistance heating vapor deposition method using a low melting point material.

Further, the low melting point material may be MgF2, sio, 5102
, CaF2, NaF and ZnS.

Further, the formation of the protective film is performed by an electron beam evaporation method.
The growth rate may be less than 10 people/sec.

(Example) The present invention will be described below with reference to an example.The semiconductor laser device of the following example differs in its basic structure from a conventionally known edge-emitting type. A film mainly composed of sulfur is formed on the end surface, and an end surface protection fill is formed on the film mainly composed of sulfur.
It is characterized by the formation of Therefore, in the following description, the process and structure of forming the end face will be mainly explained.

FIG. 1 is a perspective view schematically showing the vicinity of the front end face of the semiconductor laser device of the first embodiment.

The manufacturing process of this example will be explained.

As shown in FIG. 2(a), AlG
A stacked structure 12 containing an aAs active layer 16 was grown and resistive electrodes 13, 14 were formed on both sides.

Next, the resonator was cleaved to a predetermined resonator length using a known cleavage method to form a bar 15 in which a plurality of resonator units were connected in a direction perpendicular to the resonator direction (Fig. 2(b) 〉
).

The cleavage bar 15 was quickly placed in a 10% aqueous solution 20 of (NH4)2S and immersed for 3 minutes at room temperature to perform a surface treatment on the cleaved surface (FIG. 2(C)). As a result, a film 18 containing sulfur was formed on the end face.

Thereafter, the bar 15 is washed with water and then dried, and a reflective film 17 with a reflectance of 4% made of an Al2O3 film is applied to the front end face and an Al film 17 is applied to the back end face using a normal electron beam evaporation method.
A reflective film having a multilayer structure of 2O3 and amorphous S and having a reflectance of 95% was formed. Thereafter, the bar 15 was further cleaved to obtain a semiconductor laser device.

FIG. 3 shows the injection current vs. front output characteristic (curve A) of the semiconductor laser device obtained through the above steps. For comparison, curve B shows the injection current vs. front output characteristic of a semiconductor laser device having the same configuration as the conventional one, that is, in which a reflective film is directly formed on the rear end facet of cleavage.

In this conventional example, the element deteriorates due to end face destruction at an optical output of approximately 200 mW, whereas in this example, a maximum optical output of approximately 600 mW can be obtained, and at that point there is no end face destruction. It turns out that this does not occur.

In order to prove that the above fact is due to the reduction of surface states caused by the oxide film, we actually measured the surface state density and found that the semiconductor laser device of this example has a density of approximately 10" It was confirmed that it was 10"cm"2.eV". When a similar process was performed on a GaAs-based semiconductor laser device, the result was 10" to 1012 cm m-2-e
V-' was the smallest, and no effective surface level reduction as described above was observed.

Therefore, it is presumed that the above-mentioned large reduction effect on the surface state density is caused by the presence of AI, contrary to what has been conventionally thought.

As described above, in order to improve the facet destruction output of a semiconductor laser device, it is important that sulfur be included in the solution used for facet treatment.

As described above, in the first embodiment, the protective film 17 made of an Al2O3 film was formed on the end face by the usual electron beam evaporation method. However, for a semiconductor laser device having an end face protection film 17 formed by electron beam evaporation or sputtering, even if the surface is treated with an (NH4)2S solution, the degree of improvement in high output characteristics is limited. There were some things that weren't high enough. This is because the natural oxide film is removed by the surface treatment with the (NHJ)2S solution, and the sulfur-containing film 18 formed in its place deteriorates during the process of forming the protective film 17 by electron beam evaporation or sputtering. This is thought to be due to the fact that it can sometimes happen.

Protective film 1 is formed by electron beam evaporation method or sputtering method.
When forming the laser beam 7, secondary electrons and ions are generated during these steps and may collide with the end face on the laser beam emission side. In this case, sulfur is released from the sulfur-containing film 18 formed on the end face on the laser beam emission side, and the semiconductor surface from which the sulfur is removed is exposed. The semiconductor surface exposed at the end facet on the laser beam emission side may be oxidized by trace amounts of oxygen present in the vapor deposition apparatus.

Next, during the step of forming the protective film 17, the film 18 containing sulfur is
A second embodiment that does not cause deterioration will be described.

In this embodiment, after the end face of the bar 15 on the laser beam emitting side is treated in the same manner as in the first embodiment, a protective film 17 is placed on the end face.
To form the bar 15, the bar 15 was set in the chamber of a resistance heating vapor deposition apparatus.

Next, in the chamber, the Mo board on which the MgF2 granular crystals were mounted was heated to a temperature of about 1600° C., thereby depositing MgF2 on the laser emitting end face of the bar 15. In this way, a protective film 17 made of MgF2 was formed on the end face of the bar 15 on the laser beam emission side.

MgF2 (melting point: 1265°C) is a material with a relatively low melting point, so it can be made using a resistance heating vacuum evaporation method.
A high quality end face protection film 17 could be obtained. This M
5fO1S102, (aF2, NaF, ZnS, etc.) have a relatively low melting point and can be formed into a high-quality end face protection film 17 by resistance heating vapor deposition, similar to gF2.

During the process of forming the end face protection film 17 using the resistance heating vacuum evaporation method, unlike during the process using the electron beam evaporation method, secondary electrons do not collide with the end face, and sputtering is used. Unlike during the process, ions did not collide with the end face.

Therefore, when the end face protection film 17 is formed using a resistance heating vacuum evaporation method, the sulfur-containing film 18 on the end face is
No damage was sustained. Note that in order to form the end face protection film 17 using a resistance heating type vacuum deposition method, it is preferable that the melting point of the material to be deposited is relatively low. especially,
The melting point of the protective film material is preferably about 2000°C or less. In this specification, a material having a melting point of 2000°C or less will be referred to as a low melting point material.

A semiconductor laser device thus obtained and a semiconductor laser device in which an Al2O3 protective film 17 was formed on the end face by sputtering after end face treatment (comparative example)
The results of a comparative experiment with

First, a comparison was made regarding the relationship between optical output and end face deterioration. As a result, in the comparative example, end face destruction occurred during operation at a light output of 180 mW. On the other hand, in the semiconductor laser device of this example, even when operating at an optical output of 300 mW,
Stable laser oscillation was maintained without end face destruction. Similar results were obtained even when the above experiment was conducted after the semiconductor laser device of this example was left for a long period of time.

Next, after leaving the semiconductor laser device of this example and the comparative example in an air atmosphere for 6 months, they were inserted into a chamber and
The end face protection film 17 formed by r' ion sputtering was removed, and the chemical bonding state at the interface between the semiconductor crystal and the protection film was analyzed by X-ray photoelectron spectroscopy (xPS). As a result,
At the interface between the semiconductor crystal and the protective film 17 in this embodiment, Ga
It was also found that no bonding between As and oxygen occurred.

On the other hand, at the interface between the semiconductor crystal and the protective film in the comparative example, Ga
It was also found that a bond between As and oxygen occurred.

This is because during the process of forming the edge protection film of the comparative example,
This is because the sulfur-containing film on the end face is damaged by charged particles, which causes oxygen to become trapped on the exposed semiconductor surface.

In the semiconductor laser device of this embodiment, the protective film 17 made of a low melting point material is formed on the sulfur-containing film 18 by the resistance heating vapor deposition method. No peeling occurred from the end face. Therefore, in the semiconductor laser device of this example, even if high output operation was performed for a long period of time, oxidation was prevented from progressing at the interface between the protective film 17 and the semiconductor crystal. Therefore, in the semiconductor laser device of this example, since the increase in non-radiative recombination centers was suppressed, deterioration of the end facet was suppressed, and stable laser oscillation at high output could be performed for a long period of time.

Next, a third embodiment will be described with reference to FIG.

By the same method as in the first and second embodiments, the end face of the bar 15 on the laser light emitting side, which is the cleavage plane, is treated to form a sulfur-containing film 18 on the end face. In order to form a protective film 17 on the end face, the bar 15 was set in a chamber of a resistance heating vapor deposition apparatus. Next, in a chamber into which oxygen (pressure 1X10-2 Pa) was introduced,
The MO board on which the SiO granular crystals were placed was heated to a temperature of about 1700° C. or higher to evaporate the SIO. A protective film 17a made of 5i02 was formed on the end face by the reaction between Sio and oxygen in the atmosphere (
(See Figure 4). The thickness of the protective film 17a made of 5i02 was set to λ/(2n). After that, Al2O3 is deposited on the protective film 17a by electron beam evaporation.
(See FIG. 4). The thickness of the protective film 17b was λ/(4n). In this way, the reflectance of the end face on the laser beam emission side was set to 5%.

Since SiO is also a material with a relatively low melting point, it can be used as a high-quality end face protection film by using a resistance heating vacuum evaporation method without damaging the sulfur-containing film.

In this embodiment, the protective film 17b was formed on the protective film 17a by electron beam vapor deposition, but since the sulfur-containing film 18 is covered with the protective film 17a formed by resistance heating vapor deposition, No damage was caused by scattered electrons from electron beam evaporation.

Note that the end face protection film 17 includes the protection film 17a and the protection film 17.
The film is not limited to two layers consisting of b, but may be a multilayer film consisting of three or more layers.

In this way, in the second and third embodiments, after the end face treatment,
A protective film made of a low melting point material was formed on the end face on the laser beam emission side by a resistance heating vapor deposition method.

However, when a material with a relatively high melting point, such as A1203 (melting point 2046° C.) is used as the material for the protective film, it is difficult to form the film by the resistance heating vapor deposition method.

A fourth embodiment in which a protective film made of a material with a relatively high melting point is formed by electron beam evaporation will be described below.

In this example, after performing edge treatment with a sulfur-containing solution as in other examples, the film formation rate was set at 5 Å/sec.
Semiconductor laser devices having Al2O3 protective films formed at a rate of 10 people/see, 12 Å/sec, and 15 Å/sec were fabricated.

FIG. 5 shows the relationship between the current vs. output characteristics and the film formation rate of the semiconductor laser device of this example. In the figure, [■, I,
The lines indicated by J and K indicate the film formation rate of 5 Å/sec, 10 persons/5ees 12 A/sec, respectively.
This corresponds to the optical output characteristics of a semiconductor laser device having a protective film of e and 15 Å/sec.

FIG. 6 is a graph showing the relationship between maximum optical output and protective film formation rate. For comparison, the maximum optical output of a semiconductor laser device without end face treatment is shown by a broken line.

As can be seen from FIGS. 5 and 6, as the protective film formation rate increases, the maximum optical output decreases and approaches the maximum optical output of a semiconductor laser device without end face treatment.

This is because when the output amount of the electron beam is increased in order to increase the formation rate of the protective film, a large number of high-energy scattered electrons such as secondary electrons are generated, and the scattered electrons cause the bar 15 to emit the laser beam. It is thought that this is because the sulfur-containing film 18 formed on the end face is damaged.

As can be seen from FIG. 6, the influence of this damage on the maximum optical output is significant when the protective film formation rate is 10 people/sec or more. However, when the protective film formation rate was 10 persons/sec or less, a high maximum optical output of 540 toW or more was obtained. This means that the Al2O3 film formation rate is 1
It is thought that this is because the sulfur-containing film formed on the laser beam emitting end face of the bar 15 is hardly damaged if it is 0 Å/sec or less.

In addition, on the end face on the side different from the laser beam emission side end face,
An experiment similar to the one described above was conducted. As a result, the Al2O3 film and S
It was found that there is no dependence as described above in the relationship between the formation rate of the i-film and the optical output characteristics.

Therefore, in order to obtain a high maximum optical output, the formation rate of the protective film on the end facet of the laser beam emitting side must be at least 10 Å/
It is preferable to set it to below sec.

In addition, in any of the above examples, (NH4)2S
Although the surface treatment was performed using an aqueous solution, the surface treatment may be performed using an undiluted solution instead of an aqueous solution, or it is also possible to use other solvents.

Below, the stock solution of (NH4)23 and its 10% aqueous solution,
A fifth example will be described in which end face treatment was performed using each of the stock solution of (NH4)2sx and its 10% aqueous solution. Here, (NHJ)23X means (NH4)2S and (
NH4)232, and X, which indicates the sulfur composition ratio, is a real number from 1 to 2.

Figure 7 shows the stock solution and 10% aqueous solution of (NH4)2S, (
This is a graph showing the end face destruction output (mW) of the semiconductor laser device of this example in which the end face was treated using each of the stock solution and 10% aqueous solution of NH4)2Sx and the semiconductor laser device without the end face treatment (comparative example). be.

As can be seen from this figure, the end face destruction output of the semiconductor laser device in which end face treatment was performed using each of the stock solution and 10% aqueous solution of (NH4)2S and the stock solution and 10% aqueous solution of (NH4)23X is as follows: This was significantly improved compared to the end-face breakdown output of the previous semiconductor laser device.

Note that the thickness of the AI GaAs active layer of the semiconductor laser device of this example and the semiconductor laser device of the comparative example is thicker than the thickness of the AIGaAS active layer of the semiconductor laser device whose experimental results are shown in FIG. Therefore, in the semiconductor laser devices of this example and the comparative example, the optical density is higher (and the end face destruction output is lower) than the semiconductor laser device whose experimental results are shown in FIG.

In this example, using the stock solution and 10% aqueous solution of (NH4)2S, and the stock solution and 10% aqueous solution of (NH4)2S,
I processed the end face of a semiconductor laser device, but (NH4)2
Similar effects can be obtained not only when using an S solution or a (NH4)2Sx solution but also when a sulfur alkali metal compound solution is used. That is, the material used for the surface treatment is not particularly limited as long as a sulfur-containing film can be formed on the end face of the semiconductor laser device.

Next, an experiment conducted to determine the relationship between the sulfur concentration of a sulfur-containing solution and the treatment time required for end face treatment with the solution and its results will be described.

In the experiment, the sulfur concentration was 0. 015 not/Q,
0°15 mol/Q s and 0. 5mol/i
In each solution ((NH4)2S solution), AlGa
After immersing the As crystal for a predetermined period of time, the surface of the AlGaAs crystal was evaluated by Auger electron spectroscopy. Note that the solution temperature during immersion was about room temperature.

Figure 8 shows Al obtained from the Auger electron spectrum.
2 is a graph showing the relationship between the Auger signal intensity of oxygen present on the surface of a GaAs crystal and the immersion time. In the graph, the relationship when the sulfur concentration of the solution used is 0.015 mol/Q is a line, and the relationship when it is 0.15 mol/R is a line E. The relationship when it is 5 mol/l is shown by line F.

As this graph shows, in any concentration of solution,
As the immersion time increased, the oxygen Auger signal intensity decreased and approached the background signal level.

Figure 9 shows the relationship between the immersion time (time required for oxygen removal) and the sulfur concentration of the solution until the Auger signal intensity of oxygen reaches the background level, obtained from the above experimental results.
It is a log-log graph showing line G).

In the graph, N is an alkali metal compound solution of sulfur.
Also shown is the relationship (dashed line) between the immersion time until the Auger signal intensity of oxygen reaches the background level and the sulfur concentration of the solution when an a2S aqueous solution is used as the treatment solution.

As can be seen from FIG. 9, the immersion time until the Auger signal intensity of oxygen reaches the bank ground level and the sulfur concentration of the solution are almost inversely proportional. This means that A
Oxygen existing as an oxide film etc. on the lGaAs crystal surface is
As shown in the following reaction formula (1), it is shown that sulfur is removed from the AlGaAs crystal surface by reacting with sulfur in the solution.

Oxide dry sulfur - sulfide + oxygen (1) The rightward reaction rate of the above reaction is expressed as in the following equation (2).

−d[oxide] /dt= K・[oxide]・[S](
2) Here, [oxide] is the concentration of oxide on the AlGaAs crystal surface, [3] is the sulfur concentration of the solution, K is the rate constant, and t
is the time elapsed from the start of immersion. The left side of the above equation (2) is the time differential value of [oxide], and is the time differential value of [oxide].
It shows the rate at which oxides on the crystal surface are removed from the surface at a certain time.

[Oxide] is obtained as a function of time t as shown in the following equation (3) by solving the above differential equation (2).

[Slt
(3) Here, [oxide] θ is the time at the start of immersion (1=
0) [oxide]. The total amount of sulfur in the solution is
Since it is much larger than the total amount of oxides on the AlGaAs crystal surface, when solving the above differential equation (2),
[S] was treated as a constant that does not depend on time.

From the above equation (3), the time t0 required for the [oxide] to decrease by 99% of the [oxide] S is shown in the following equation (4).

tc - (1n 1 0 0) / (K ・
[S co ) (4) The above equation (4) shows the following. In other words, the time required for 99% of the oxygen present as an oxide film on the AlGaAs crystal surface to react with sulfur in the solution and be removed from the AlGaAs crystal surface depends on the sulfur concentration in the solution. It means that it is inversely proportional. This agrees with the experimental results shown in the graph of FIG.

Expression (4) above is expressed as the relationship shown in the graph of Figure 9 (line G).
By fitting, the following equation (5) was obtained.

tc = 1. 5/[S] (5) Here, the unit of 1c is [seconds], and the unit of [S] is [no
1zQ], the unit of 1.5 is [seconds/logic O1Z intersection].

When using a solution with a sulfur concentration of 0.015 mof/Q, t,=too seconds can be obtained from the above equation (5). Therefore, if a solution with a sulfur concentration of 0.015 mol/Q is used and the end face treatment is performed for less than 100 seconds, the oxide film existing on the AlGaAs crystal surface on the end face cannot be completely removed. Can not. That is,
In order to remove most of the oxide film existing on the AlGaAs crystal surface, it is necessary to perform the end face treatment for a time longer than t0 seconds as shown in the above equation (5).

In this way, from the above experimental results and their considerations, Al
The immersion time required to remove most of the oxide film present on the GaAs crystal surface was obtained.

Based on this, by treating the end face with an appropriate treatment time depending on the sulfur concentration of the solution used, it is possible to avoid insufficient removal of the end face oxide film due to insufficient end face treatment time, and to prevent This eliminates the waste of time spent on end face treatment.

As can be seen from the graph in FIG. 9, when Na2S is used as the edge treatment solution, the oxide film on the AlGaAs crystal surface is removed in the same manner as when the (NH4)2S solution is used. However, (NH4)2S solution or (
The semiconductor laser device whose end face was processed using the NH4)2sx solution showed better reliability than the semiconductor laser device whose end face was processed using the Na2S solution. Among the solutions containing sulfur, (NH4)2S solution and (NH4)2
The sx solution is a particularly excellent end face treatment solution from the viewpoint of reliability of semiconductor laser devices.

In any of the above examples, after the wafer is cleaved in the atmosphere, the cleaved plane is treated with a 10% aqueous solution of (NH4)2S.
The light-emitting side end face was treated by immersing it in water.

In this case, in order to perform the cleavage of the sea urchin in the atmosphere, the cleavage plane came into contact with the atmosphere immediately after cleavage.

A sixth embodiment in which cleavage is not performed in the atmosphere will be described below with reference to FIG.

After forming the laminated structure 12 on the substrate 11 (FIG. 10(a)) in the same manner as the other examples, 10
% aqueous solution 20, and cleaved the wafer in the aqueous solution 20 using tweezers 40, thereby forming bars 15 having a predetermined resonator length (FIG. 10(b)). After the resonator end face of the semiconductor laser device was formed by cleavage in the aqueous solution 20, the bar 15 was immersed in the aqueous solution for 3 minutes to perform surface treatment on the cleaved plane.

In this way, the cleaved end faces were covered with a sulfur-containing film without coming into contact with the oxygen-containing atmosphere.

After this, the bar 15 was washed with water and dried (Fig. 10 (
C)) After that, a reflective film having a reflectance of 4% and consisting of an Al2O3 film was formed on the end face on the laser beam emission side by a normal electron beam evaporation method. Further, a reflective film having a reflectance of 95% and having a multilayer structure of Al2O3 and amorphous Si was formed on the other end face. Thereafter, the bar 15 was further cleaved to obtain a semiconductor laser device.

When the surface unit density was measured, it was confirmed that the semiconductor laser device of this example had a density of approximately 107 cm<-2 >eV-'. Similar measurements were performed on a comparative example in which the wafer was cleaved in the atmosphere, and the result was approximately 109 cm-2.
eV-' was the smallest, and no effective reduction in surface state density as described above was observed.

As described above, in this example, by cleaving the wafer in the (N114)2S aqueous solution, it was possible to prevent the cleaved plane from being naturally oxidized by the atmosphere. For this reason, (NHa)
The surface treatment of the cleavage plane in the 2S aqueous solution was effectively performed, and the surface order density caused by the oxide film was reduced.

(Effects of the Invention) As described above, according to the present invention, the sulfur-containing film is made of AlG
Since it is formed on the end face of a semiconductor laser device having an aAs active layer, the surface level of the end face is greatly reduced. Therefore, it is possible to effectively suppress deterioration due to heat generation of the light emitting end face due to surface recombination, and it is possible to increase the output of the AlGaAs semiconductor laser device with high reliability.

In addition, by treating the end face with a solution containing sulfur,
An end face with few surface states covered with a film containing sulfur can be easily formed. By optimizing the type and formation method of the protective film formed on this end face, a semiconductor laser device with excellent high output characteristics can be manufactured with high yield without damaging the sulfur-containing film.

In addition, by processing the end face with an appropriate processing time depending on the sulfur concentration of the solution used, the removal of the oxide film on the end face will not occur due to insufficient end face processing time, and the end face treatment will take more time than necessary. This eliminates unnecessary work.

Further, by cleaving the wafer in a solution containing sulfur, oxidation of the end face is more effectively suppressed, and a highly reliable semiconductor laser device with improved output can be obtained.

4.-■ No. 11 1 Figure 1 is a perspective view schematically showing the vicinity of the end face on the laser beam emission side of the apparatus of the first embodiment, and Figures 2 (a) to (C) are views of the apparatus of the first embodiment. A perspective view for explaining the manufacturing process, FIG. 3 is a diagram showing the injection current vs. optical output characteristic of the semiconductor laser device of the third embodiment, and FIG. 4 is a diagram showing the laser beam emitting end face of the device of the third embodiment. A perspective view schematically showing the vicinity, FIG. 5 is a graph showing the relationship between current vs. front output characteristics and film formation rate of the device of the fourth embodiment, and FIG. 6 shows the maximum light output and protection of that embodiment. FIG. 7 is a graph showing the relationship with the film formation rate; FIG. 7 is a graph showing the end face destruction output of the semiconductor laser device of the fifth embodiment;
The figure is a graph showing the relationship between the Auger signal intensity of oxygen and the immersion time at the end face of the fifth embodiment, and Figure 9 shows the period of immersion and solution time until the Auger signal intensity of oxygen reaches the background level. 10(a) to <c> are cross-sectional views for explaining the manufacturing method of the sixth embodiment, and FIG. 11 <a> and <b> are respectively p Figures 12(a) and 12(b) schematically show the state in which carrier accumulation layers are formed on the surfaces of p-type and p-type GaAs, and inversion layers are formed on the surfaces of p-type and p-type semiconductors, respectively. FIG.

11... Semiconductor substrate, 12... Laminated structure, 13.1
4... Electrode, 15... Bar 16... Active layer, 1
8... Membrane containing sulfur, 17.17a, 17b... Protective film, 20... (NH4)2S aqueous solution.

that's all

Claims (1)

[Claims] 1. An edge-emitting semiconductor laser device having an AlGaAs active layer and having a protective film formed on the end facet, comprising: a film containing sulfur between the end facet and the protective film; A semiconductor laser device in which 2. The semiconductor laser device according to claim 1, wherein the protective film is made of a low melting point material. 3. The low melting point material is MgF_2, SiO, SiO_
3. The semiconductor laser device according to claim 2, wherein the semiconductor laser is selected from the group consisting of: 2.2, CaF_2, NaF, and ZnS. 4. A method for manufacturing an edge-emitting semiconductor laser device having an AlGaAs active layer and a protective film formed on the end facets, including the step of treating the end facets with a solution containing sulfur, and then treating the end facets with a solution containing sulfur. 1. A method of manufacturing a semiconductor laser device, the method comprising the step of forming a semiconductor laser device. 5. The sulfur-containing solution is (NH_4)_2S stock solution,
5. The method for manufacturing a semiconductor laser device according to claim 4, wherein the method is one selected from the group consisting of (NH_4)_2S_x stock solution, (NH_4)_2S_x aqueous solution, and (NH_4)_2S_x aqueous solution. 6. The semiconductor laser device according to claim 4, wherein when the sulfur concentration of the sulfur-containing solution is X mol/l, the time for treating the end face with the sulfur-containing solution is 1.5/X seconds or more. Production method. 7. The method of manufacturing a semiconductor laser device according to claim 4, wherein the end facet is formed by cleaving a wafer in the sulfur-containing solution, and then the end facet is treated with the solution. 8. The method of manufacturing a semiconductor laser device according to claim 4, wherein the protective film is formed by a resistance heating vapor deposition method using a low melting point material. 9. The low melting point material is MgF_2, SiO, SiO_
9. The method for manufacturing a semiconductor laser device according to claim 8, wherein the material is selected from the group consisting of: 2, CaF_2, NaF, and ZnS. 10. The method of manufacturing a semiconductor laser device according to claim 4, wherein the protective film is formed by electron beam evaporation at a growth rate of 10 Å/sec or less.