JPH0897510A - Semiconductor laser manufacturing method and semiconductor laser - Google Patents

Abstract

(57) [Abstract] [Purpose] A method of manufacturing a semiconductor laser capable of easily improving the processing accuracy of a ridge and suppressing the lateral spread of a current to achieve a lower threshold and a higher output. , And a semiconductor laser. [Structure] On the (100) plane of the semiconductor substrate 1, [01
1] A selective mask 2 having a stripe-shaped opening extending in the direction 1) is formed, and using this as a mask, the buffer layers 3 and n
Type clad layer 4, active layer 5, p type clad layer 6, band discontinuity relaxation layer 7, and cap layer 8 are sequentially grown selectively,
A ridge 50 is formed in which the cross section in the stripe width direction has a regular mesa shape and the cross section in the stripe length direction is a bilaterally symmetrical hexagon.

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 a semiconductor laser, and more particularly to a method for manufacturing a semiconductor laser having a ridge structure and a semiconductor laser.

[0002]

2. Description of the Related Art FIG. 18 is a sectional view showing a structure of a visible light laser diode which is an example of a conventional semiconductor laser.
In the figure, 1 is an n-GaAs substrate, 3 is n-GaAs
Buffer layer, 4 is n-AlGaInP clad layer, 5a
Is a GaInP active layer, and 6a and 6b are first and second p-A.
lGaInP clad layer, 15 p-GaInP etching stopper layer, 7 p-GaInP band discontinuity relaxation layer, 8 p-GaAs cap layer, second p-AlG
The aInP clad layer 6b, the p-GaInP band discontinuity relaxation layer 7, and the p-GaAs cap layer 8 form a stripe-shaped forward mesa ridge extending in the <01/1> direction (so-called forward mesa direction). Reference numeral 10a denotes an n-GaAs current blocking layer filling the ridge side, 11 denotes a p-GaAs contact layer formed on the ridge and on the n-GaAs current blocking layer 10a, 12 denotes an n-side electrode, 13
Is a p-side electrode, and 9a is a selection mask.

Next, a manufacturing process of a conventional visible light laser diode will be described. First, as shown in FIG. 18 (a),
MOCVD (Metal Organic Chemical Vapor Depositio)
n: metal-organic vapor phase epitaxy) on the n-GaAs substrate 1, n-GaAs buffer layer 3, n-AlGaInP cladding layer 4, GaInP active layer 5a, first p-AlG
aInP clad layer 6a, p-GaInP etching stopper layer 15, second p-AlGaInP clad layer 6
b, p-GaInP band discontinuity relaxation layer 7, p-GaA
The s-cap layer 8 is successively crystallized. Next, p-Ga
A selective mask such as a SiN film or a SiON film is formed on the As cap layer 8 by CVD (Chemical Vapor Deposition), and a resist is applied on the selective mask. A stripe-shaped selection mask 9a extending in the <1/1> direction is formed. Next, as shown in FIG. 18B, using the selective mask 9a as a mask, the p-GaAs cap layer 8 is selectively etched with a tartaric acid-based etching solution, and then p-GaIn is etched with a hydrochloric acid-based etching solution.
The P-band discontinuous layer 7 is selectively etched, and then the p-AlGaInP cladding layer 6b is selectively etched with a sulfuric acid-based etching solution until it reaches the p-GaInP etching stopper layer 15 to form a striped ridge (FIG. 18 (c)). Next, as shown in FIG. 18D, an n-GaAs current blocking layer 10a is selectively grown on the ridge side until the height of the ridge is reached, and then a selective mask 9a is formed.
Is removed, a p-GaAs contact layer 11 is grown on the entire surface, and finally an n-side electrode 12 and a p-side electrode 13 are formed by vapor deposition or the like (FIG. 18 (e)).

Next, the operation will be described. n-side electrode 12
When a forward voltage is applied to the p-side electrode 13 and the p-side electrode 13, the current is present in the current blocking layer 10a. Therefore, the pnp junction formed between the contact layer 11, the current blocking layer 10a, and the etching stopper layer 15 blocks the reactive current. Then, the current flows concentratedly in the ridge portion, and light is generated by radiative recombination of electrons and holes injected into the active layer 5 near the ridge. The generated light is guided along the stripe-shaped ridge and is reflected and amplified between a pair of cleaved end faces (not shown) to generate laser oscillation.

[0005]

The conventional semiconductor laser is constructed as described above, but an etching solution having sufficient selectivity so that GaInP is etched and AlGaInP is not etched when forming a ridge. That is, since there is no selective etchant, the second p-AlGaInP layer 6b is also etched when the p-GaInP band discontinuity relaxation layer 7 is etched with a hydrochloric acid-based etching solution. For this reason, Al is formed between laser diodes simultaneously formed on the wafer surface and also between different positions of the same laser diode chip.
A difference occurs in the remaining thickness of the GaInP cladding layer 6b, and when the AlGaInP layer 6b is subsequently etched, the AlGaInP and GaI of the sulfuric acid-based etching solution are also used.
Since the nP selection ratio is small, there is a portion where the p-GaInP etching stopper layer 15 is etched,
There was a problem that a part where the AlGaInP clad layer 6b was not completely removed was generated, and it was difficult to form a good and accurate ridge.

Further, in the conventional semiconductor laser, the current injected into the ridge spreads in the cavity length direction, that is, in the lateral direction at the portion where the ridge and the etching stopper layer 15 are in contact with each other. However, there is a problem that it hinders lowering of the threshold value and higher output of the laser diode.

The present invention has been made in order to solve the above-mentioned problems, and it is possible to easily improve the machining accuracy of the ridge, suppress the lateral current spread, and lower the threshold. An object of the present invention is to provide a semiconductor laser manufacturing method and a semiconductor laser capable of achieving higher value and higher output.

[0008]

According to the method of manufacturing a semiconductor laser of the present invention, a selective mask having stripe-shaped openings extending in the <011> direction is formed on the {100} plane of a first conductivity type substrate. , The first conductivity type cladding layer, the active layer, the second layer on the {100} surface of the substrate using this as a mask.
A double heterostructure including a conductivity type clad layer is selectively grown, the surfaces of the active layer and the first conductivity type clad layer are covered with the second conductivity type clad layer, and the cross section in the stripe width direction has a normal mesa shape. There is formed a ridge stripe having a hexagonal cross-section in the stripe length direction which is bilaterally symmetrical.

Further, according to the method of manufacturing a semiconductor laser of the present invention, <0/1 is formed on the {100} plane of the first conductivity type substrate.
A selective mask having a stripe-shaped opening extending in the 1> direction is formed, and using this as a mask, {10
0} plane, a double heterostructure including a first conductivity type clad layer, an active layer, and a second conductivity type clad layer is selectively grown, and the second conductivity type clad layer is used to form the active layer and the first conductivity type clad layer. The surface is covered, and the cross section in the stripe width direction is a bilaterally symmetrical hexagonal shape, and the cross section in the stripe length direction is an isosceles trapezoidal shape to form a ridge stripe.

According to the method of manufacturing a semiconductor laser of the present invention, <001> is formed on the {100} plane of the first conductivity type substrate.
Forming a selective mask having stripe-shaped openings extending in the <101> direction or the <010> direction, and using this as a mask on the {100} plane of the substrate, a first conductivity type clad layer, an active layer, and a second conductivity type clad layer Is selectively grown to form a rectangular ridge stripe in which the surfaces of the active layer and the first conductivity type cladding layer are covered with the second conductivity type cladding layer.

In the method of manufacturing a semiconductor laser, the ridge stripe is formed, the selection mask is removed, and the forbidden band width is larger than that of the active layer on the {100} plane of the substrate around the ridge. A current blocking layer made of a large material is buried and formed at least to a height reaching the height of the ridge, and a laser end face of the semiconductor laser is formed in a region of the ridge stripe having no active layer.

In the method of manufacturing the semiconductor laser, the end face of the ridge is a cavity end face of the semiconductor laser.

In the method of manufacturing the semiconductor laser, a material that is more likely to migrate than the other materials forming the ridge is used as the material forming the active layer, and the ridge is formed by selective growth. This is done under the condition that the material to be migrated easily.

In the method of manufacturing a semiconductor laser, the second conductivity type cladding layer is a p-type cladding layer, and the step of selectively growing the second conductivity type cladding layer is performed.
The p-type dopant and the n-type dopant are mixed in a predetermined ratio so that the second conductivity type clad layer formed on the side surface of the ridge has a high resistance, and the mixed gas is supplied in the atmosphere.

In the method of manufacturing a semiconductor laser, the first conductivity type clad layer is a p-type clad layer, and the step of selectively growing the first conductivity type clad layer is performed.
A p-type dopant and an n-type dopant are mixed in a predetermined ratio so that the ridge side surface region of the first conductivity type cladding layer has a high resistance, and the mixed gas is supplied in an atmosphere.

The semiconductor laser according to the present invention has a first conductivity type clad layer disposed on the {100} plane of the first conductivity type semiconductor substrate, and a {1} of the first conductivity type clad layer.
00} surface, the active layer and the first layer
A double heterostructure constituted by a second conductivity type clad layer arranged so as to cover the conductivity type clad layer;
It has a stripe-shaped ridge extending in the <011> direction whose cross-sectional shape is a regular mesa shape.

Further, the semiconductor laser according to the present invention has a first-conductivity-type cladding layer disposed on the {100} plane of the first-conductivity-type semiconductor substrate, and a {1} -type first-conductivity-type cladding layer.
00} surface, the active layer and the first layer
A double heterostructure constituted by a second conductivity type clad layer arranged so as to cover the conductivity type clad layer;
Its cross-sectional shape is a symmetrical hexagonal shape <0/1
It has a striped ridge extending in the 1> direction.

Further, the semiconductor laser according to the present invention has a first conductivity type clad layer disposed on the {100} plane of the first conductivity type semiconductor substrate and a {1} of the first conductivity type clad layer.
00} surface, the active layer and the first layer
A double heterostructure constituted by a second conductivity type clad layer arranged so as to cover the conductivity type clad layer;
It has a stripe-shaped ridge extending in the <001> direction or the <010> direction whose cross-sectional shape is rectangular.

In the semiconductor laser, the second conductivity type cladding layer is arranged so as to cover the end face of the ridge in the stripe length direction, and the periphery of the ridge has a larger forbidden band width than the active layer. It is embedded in the current blocking layer.

Further, in the above semiconductor laser, the region near the first conductivity type cladding layer on the side surface of the ridge has a high resistance.

Further, in the semiconductor laser, the end face of the ridge constitutes a cavity end face, and the second conductivity type clad layer is located at the cavity end face of the semiconductor laser and the active layer and the first conductivity type. It is arranged so as to cover the clad layer.

[0022]

According to the method of manufacturing a semiconductor laser of the present invention, a double hetero structure including a first conductivity type cladding layer, an active layer and a second conductivity type cladding layer is selectively grown on the {100} plane of a substrate, The surfaces of the active layer and the first conductivity type clad layer are covered with the second conductivity type clad layer,
A ridge stripe was formed in which the cross section in the stripe width direction was a forward mesa shape and the cross section in the stripe length direction was a bilaterally symmetric hexagonal shape.Therefore, after crystal growth was performed to form the ridge, selection was made. Since it is not necessary to repeatedly perform etching, it is possible to reduce variations in the processing accuracy of the ridge and to easily form the ridge. Further, the second conductivity type clad layer and the active layer formed on the side surface of the first conductivity type clad layer are thin,
In addition, since the incorporation efficiency of the dopant is lowered and the region near the first conductivity type cladding layer on the side surface of the ridge is formed to have high resistance, the reactive current is blocked in the region and the current injected into the ridge is blocked. Is injected into the active layer, the spread of the current in the width direction of the resonator can be suppressed.

Further, according to the method of manufacturing a semiconductor laser of the present invention, the double hetero structure including the first conductivity type clad layer, the active layer and the second conductivity type clad layer is selectively grown on the {100} plane of the substrate. Then, the surfaces of the active layer and the first conductivity type clad layer are covered with the second conductivity type clad layer, and the cross section in the stripe width direction has a symmetrical hexagonal shape, and the cross section in the stripe length direction is the same. Since the ridge stripe having a trapezoidal shape is formed, it is not necessary to repeatedly perform selective etching after crystal growth for forming the ridge, and it is possible to reduce variations in ridge processing accuracy. The ridge can be easily formed. In addition, the second conductivity type clad layer and the active layer formed on the side surface of the first conductivity type clad layer have a small thickness and the dopant uptake efficiency is low, and the first conductivity type clad layer on the side surface of the ridge is reduced. Since the region near the layer is formed to have a high resistance, the reactive current is blocked in the region and all the current injected into the ridge is injected into the active layer, thereby spreading the current in the resonator width direction. Can be suppressed.

Further, according to the method of manufacturing a semiconductor laser of the present invention, the double hetero structure including the first conductivity type cladding layer, the active layer and the second conductivity type cladding layer is selectively grown on the {100} plane of the substrate. Then, a rectangular parallelepiped ridge stripe in which the surfaces of the active layer and the first conductivity type clad layer are covered with the second conductivity type clad layer is formed. Therefore, crystal growth is performed to form a ridge. After that, it is not necessary to repeatedly perform selective etching, and it is possible to reduce variations in ridge processing accuracy.
The ridge can be easily formed. Also, the first
The second conductivity type clad layer and the active layer formed on the side surface of the conductivity type clad layer are thin, and the efficiency of taking in the dopant is low, and the region near the first conductivity type clad layer on the ridge side surface is high. Since it is formed so as to become a resistance, by blocking the reactive current in the region and injecting all the current injected into the ridge into the active layer,
It is possible to suppress the spread of current in the resonator width direction.

In the method of manufacturing the semiconductor laser, after the ridge stripe is formed, the selection mask is removed, and the forbidden band width is larger than that of the active layer on the {100} plane of the substrate around the ridge. Since the current blocking layer made of a large material is embedded and formed up to at least the height reaching the height of the ridge, the laser end face of the semiconductor laser is formed in a region having no active layer of the ridge stripe, In the step of forming the current blocking layer, the current blocking layer that does not absorb light can be provided on the cavity end facet, and the window structure can be easily obtained.

Further, in the method of manufacturing a semiconductor laser described above, since the end face of the ridge is the resonator end face of the semiconductor laser, the second conductivity type cladding layer which does not absorb light can be provided on the resonator end face, which is easy. The window structure can be obtained.

In the method of manufacturing the semiconductor laser described above, a material that is more likely to migrate than other materials that form the ridge is used as a material that forms the active layer, and the ridge is formed by selective growth of the ridge. Since the material is used under the condition that the material easily migrates, formation of the active layer on the side surface of the first conductivity type cladding layer can be prevented.

In the method of manufacturing a semiconductor laser, the second conductivity type cladding layer is a p-type cladding layer,
In the step of selectively growing the second conductivity type cladding layer, a gas in which a p-type dopant and an n-type dopant are mixed in a predetermined ratio so that the second conductivity type cladding layer formed on the side surface of the ridge has a high resistance is used. Since it is performed in the supplied atmosphere, the region near the first conductivity type cladding layer on the side surface of the ridge can have higher resistance, and the reactive current can be reliably reduced.

In the method of manufacturing a semiconductor laser described above, the first conductivity type cladding layer is a p-type cladding layer,
In the step of selectively growing the first conductivity type cladding layer, a gas in which a p-type dopant and an n-type dopant are mixed at a predetermined ratio so that the ridge side surface region of the first conductivity type cladding layer has a high resistance is supplied. I decided to do it in an atmosphere,
The side surface region of the first conductivity type clad layer can have a high resistance, and the region near the first conductivity type clad layer on the ridge side surface can have a higher resistance, and the reactive current can be reliably reduced.

Further, in the semiconductor laser according to the present invention, the first conductivity type clad layer disposed on the {100} plane of the first conductivity type semiconductor substrate and the {100} of the first conductivity type clad layer. An active layer disposed on the surface, and a second layer disposed so as to cover the active layer and the first conductivity type clad layer.
Since it has a stripe-shaped ridge having a double hetero structure composed of a conductivity type cladding layer and having a cross-sectional shape that is a forward mesa shape and extending in the <011> direction, most of the current injected into the ridge is By injecting into the active layer in the ridge which becomes the light emitting region of the laser light, it is possible to suppress the current spreading in the cavity width direction.

Further, in the semiconductor laser according to the present invention, the first conductivity type cladding layer disposed on the {100} plane of the first conductivity type semiconductor substrate and the {100} of the first conductivity type cladding layer. An active layer disposed on the surface, and a second layer disposed so as to cover the active layer and the first conductivity type clad layer.
It has a double heterostructure composed of a conductive clad layer and has a stripe-shaped ridge extending in the <0/11> direction, which is a symmetrical hexagonal cross-sectional shape. Most of the injected current is injected into the active layer in the ridge that becomes the light emitting region of the laser light,
It is possible to suppress current spreading in the resonator width direction.

Further, in the semiconductor laser according to the present invention, the first conductivity type clad layer disposed on the {100} plane of the first conductivity type semiconductor substrate and the {100} of the first conductivity type clad layer. An active layer disposed on the surface, and a second layer disposed so as to cover the active layer and the first conductivity type clad layer.
It has a double hetero structure composed of a conductive clad layer and has a stripe-shaped ridge whose cross-sectional shape is rectangular and extends in the <001> direction or the <010> direction. Most of the current can be injected into the active layer in the ridge, which becomes the light emitting region of laser light, and the current spreading in the cavity width direction can be suppressed.

In the semiconductor laser, the second conductivity type cladding layer is arranged so as to cover the end face of the ridge in the stripe length direction, and the ridge has a larger forbidden band width than that of the active layer. Since it is embedded with the current blocking layer, absorption of light at the cavity end face can be suppressed by the second conductivity type cladding layer and the current block layer, and the cavity end face can function as a window structure. it can.

Further, in the above semiconductor laser, since the region of the side surface of the ridge near the first conductivity type cladding layer has a high resistance, the reactive current in the region of the side surface of the ridge near the high resistance first conductivity type clad layer is large. By blocking all of the current and injecting all the current injected into the ridge into the active layer, the spread of the current in the cavity width direction can be further suppressed.

Further, in the semiconductor laser, the end face of the ridge constitutes a cavity end face, and the second conductivity type cladding layer is located at the cavity end face of the semiconductor laser and the active layer and the first conductivity type. Since the cladding layer is disposed so as to cover the cladding layer, absorption of light at the resonator end face can be suppressed by the second conductivity type cladding layer, and the resonator end face can function as a window structure.

[0036]

【Example】

Example 1. FIG. 1 is a sectional process view of a plane parallel to a (011) plane showing a method for manufacturing a semiconductor laser according to a first embodiment of the present invention. In the figure, 1 is n-GaAs whose surface is a (100) plane. A substrate, 3 is an n-GaAs buffer layer formed on the surface of the n-GaAs substrate 1, 2 is a first selection mask made of an insulating film, and 4 is on the (100) plane of the n-GaAs buffer layer 3. In the n-AlGaInP clad layer 5, the thickness of the formed part is about 1.5 μm, the thickness of the part formed on the (100) face of the n-AlGaInP clad layer 4 is about several hundred angstroms. It is a GaInP active layer. 6 is (10 of the active layer 5
0) surface is a p-AlGaInP clad layer having a thickness of about 1.5 μm, 7 is the p-AlGaI
A p-GaInP band discontinuity relaxation layer having a thickness of about 0.1 μm formed on the (100) surface of the nP cladding layer 6, and other materials include AlGaInP and G
p-AlGaAs with band gap between aAs
And the like are preferable. Reference numeral 8 denotes a p-GaAs cap layer having a thickness of a portion formed on the (100) plane of the p-GaInP band discontinuity relaxation layer 7 of about 0.3 to 0.4 μm, and the n-GaAs buffer layer 3 , N-AlGaInP clad layer 4, active layer 5, p-AlGaInP clad layer 6, p-GaInP band discontinuity relaxation layer 7, p-GaA
The s-cap layer 8 forms a forward mesa-shaped ridge 50. A current block layer 10 is formed so as to fill the ridge, and is a high resistance layer made of a material such as AlyGa (1-y) InP. In the conventional semiconductor laser, the clad layer, the block layer, and the contact layer form a pnp structure (or an npn structure), which blocks the reactive current flowing in the region other than the ridge 50. In the structure of the semiconductor laser of the example, even if the n-type current blocking layer is provided, the pnp structure is not obtained, so that the reactive current cannot be blocked. Therefore, the block layer needs to be a high resistance layer, and a high resistance layer such as AlyGa (1-y) InP or AlInP is used. The AlyGa (1-y) InP layer tends to have a higher resistance as the Al composition ratio y is higher. Also,
The AlyGa (1-y) InP crystal has high resistance even when undoped, but oxygen may be mixed therein, and the higher the oxygen concentration, the higher the resistance tends to be. In this case, the oxygen concentration is 1.
It is preferably 0E + 16 / cm ³ or more. Also, A
The higher the l composition, the more likely oxygen is to be incorporated into the crystal. Reference numeral 11 denotes a p-GaAs contact layer, and the material of the contact layer may be p-Ge which is lattice-matched to the GaAs substrate instead of p-GaAs. p-Ge is p
-Resistance can be made lower than that of GaAs, and it becomes easier to make contact with the electrode. Reference numeral 12 is an n-side electrode, 13 is a p-side electrode, 2 is an insulating film such as SiN or SiO, and 9 is an insulating mask such as SiN.

FIG. 2 is a perspective view showing a method for manufacturing a semiconductor laser according to the first embodiment of the present invention. In the figure, the same reference numerals as those in FIG. 1 designate the same or corresponding parts.

Next, a method of manufacturing the semiconductor laser of the first embodiment will be described with reference to FIGS. First, an insulating film 2 such as SiN or SiO is formed on the (100) surface of an n-GaAs substrate 1 shown in FIG.
1] The first selection mask 2 is formed by forming a stripe-shaped opening extending in the direction (so-called forward mesa direction) (FIGS. 1B and 2A).

Next, as shown in FIG. 1 (c), using a selective mask 2, metal organic chemical vapor deposition (Metal Organic Chemica) is performed.
l Vapor Deposition (MOCVD) method, an n-GaAs buffer layer 3, an n-AlGaInP clad layer 4, and an AlxGa (1
-x) The InP active layer 5, the p-AlGaInP cladding layer 6, the band discontinuity relaxation layer 7, and the p-GaAs cap layer 8 are selectively grown in sequence.

Here, K. Kamon, S. Takagishi and H. Mor
i, J. Crystal Growth 73 (1985) 73-76, Si formed on the {100} plane of a GaAs substrate.
A stripe-shaped opening extending in the <011> direction (so-called forward mesa direction) is formed in the N film, and AlGaA is formed in this opening.
When s is grown, the cross section in the width direction of the stripe has a forward mesa shape, and the cross section in the stripe length direction has a triangular shape with its end portion protruding outward, and has a symmetrical hexagonal shape. Crystals grow in a ridge shape, and one of the end faces in the stripe length direction has a {111} A plane at the top and a {/ 111} B plane at the bottom, and one of the side faces in the stripe width direction is {11/1} B. It is known to be a face.
The growth in the stripe width direction stops at the {11/1} B plane because the adhesion coefficient of the material at the B plane is small. Therefore, also in this embodiment, as shown in FIG.
-GaAs buffer layer 3, n-AlGaInP cladding layer 4, AlxGa (1-x) InP active layer 5, p-AlGa
InP clad layer 6, band discontinuity relaxation layer 7, and p-
The GaAs cap layer 8 sequentially grows so as to cover the surface of the lower layer, the cross section in the stripe width direction has a forward mesa shape, and the cross section in the stripe length direction has a triangular shape with its end portion protruding outward. In addition, a striped ridge 50 having a hexagonal shape with left and right symmetry is formed. The crystal growth on the {11/1} B plane grows at a much slower rate than the growth on the {100} plane. Therefore, the n-GaAs buffer layer 3, the n-AlGaInP cladding layer 4, the AlxGa1-x InP active layer 5, the p-Al
When the GaInP clad layer 6, the band discontinuity relaxation layer 7, and the p-GaAs cap layer 8 are continuously grown to form the stripe-shaped ridge 50, each of the layers is the side surface of the ridge 50 (11/1) B surface. The thickness of the laminated layer is (1
It becomes very thin with respect to the thickness laminated in the direction perpendicular to the (00) plane. The cross-sectional structure at this time is as shown in Fig. 1 (c),
Both ends of the active layer 5 in the ridge stripe width direction are covered with the cladding layer 6, and the entire active layer 5 is arranged so as to be embedded in the ridge along the ridge stripe.

Next, the first selection mask 2 is removed by a method such as wet etching or dry etching, and a second selection mask 9 is newly formed on the ridge, and this ridge is used as a mask. A high resistance layer is grown as the current blocking layer 10 so as to have the same height (FIG. 1 (d), FIG. 2).
(c)). At this time, since the periphery of the active layer 5 is filled with the cladding layers 4 and 6, the step of removing the first selection mask 2, the step of forming the second selection mask 9, and the current block layer. In the process of regrowth to form 10,
The GaInP active layer 5 is protected so as not to be damaged. As a result, both sides of the active layer 5 can be filled with the current blocking layer 10 without damaging the active layer 5.

Next, after removing the second selective mask 9 by using a method such as wet etching or dry etching, a p-GaAs contact layer 11 is grown, and n is formed on the back surface side of the substrate 1 by an electrode forming process. The mold electrode 12 and the p-type electrode 13 are formed on the surface of the contact layer 11 (FIGS. 1 (e) and 2 (d)). Finally, cleavage is performed in the portion where the active layer 5 exists, and the length in the cavity length direction is about 650.
A semiconductor laser diode element having a size of μm is obtained (FIG. 2).
(e)).

Next, the operation will be described. n-side electrode 12
When a forward voltage is applied to the p-side electrode 13 and the current, the current is blocked by the current blocking layer 10a made of a high resistance layer, the reactive current is blocked, and the current concentrates in the ridge 50 and is formed in the ridge 50. Light is generated by the radiative recombination of electrons and holes injected into the active layer 5. The generated light is guided along the striped ridge 50, reflected and amplified between a pair of cleaved end faces (not shown), and laser oscillation occurs. At this time, as described above, (11 /
1) Since the crystal growth rate is slow on the B surface, the cladding layer 4
Since the active layer 5 is laminated on the side surface of the ridge 50 with a very thin thickness, almost no laser light is generated in the active layer 5 formed on the side surface of the ridge 50. Further, since the active layer 5 and the p-AlGaInP clad layer 6 formed on the (11/1) plane of the clad layer 4 have a sufficiently small thickness and a sufficiently high resistance, the n-AlG
The reactive current that tries to pass through the (11/1) plane of the aInP clad layer 4 is caused by the high resistance active layer 5 and p-AlG.
It is blocked by the aInP clad layer 6.

In the semiconductor laser of this embodiment, the ridge 50 is formed by the selective growth using the MOCVD apparatus. After the crystal growth is performed to form the ridge as in the conventional case, the selective etching is repeated. No need. Therefore, the problem of variations in ridge processing accuracy due to variations in selective etching does not occur, and the ridge can be easily formed by shortening the process.

Further, in the semiconductor laser of the present embodiment, the reactive current that tries to pass through the (11/1) plane of the n-AlGaInP cladding layer 4 is, as described above, the active layer 5 and the p-AlGaInP cladding layer. 6, n-Al
Since it is blocked by the high resistance region formed on the (11/1) plane of the GaInP clad layer 4, all the current injected into the ridge 50 is the active layer 5 formed on the (100) plane.
Is injected into. Therefore, it is possible to obtain a high-output semiconductor laser with a low threshold value, which suppresses the current spread in the cavity width direction, that is, in the lateral direction.

Here, when selective growth of the ridge 50 is performed, the growth conditions are set to conditions such as low pressure, high temperature, and a high rotation speed when the substrate is rotated so that the material easily migrates {11/1. } The growth rate on the plane becomes slow. On the other hand, if the growth conditions are set so that the material does not easily migrate, the growth rate on the {11/1} plane becomes faster. In addition, a material that does not easily migrate has a high growth rate on the {11/1} plane, and a material that easily migrates has a low growth rate on the {11/1} plane.
For example, when the active layer 5 is made of GaInP as in the present embodiment, when the active layer 5 is grown by a normal method, as shown in FIG.
As shown in (a), an extremely thin active layer may be formed on the side surface of the ridge 50 in the stripe width direction.
However, since the material of GaInP migrates more easily than that of AlGaInP, G
The growth rate of aInP on the {11/1} plane becomes small.
Therefore, by utilizing this property, when the ridge 50 is selectively grown, the growth conditions are set so that the respective materials are easily migrated, and the active layer 5 is grown (11/1).
When the growth of the GaInP active layer 5 is suppressed on the surface, and then the AlGaInP clad layer 6 is grown,
As shown in (b), the GaInP active layer 5 is formed only on the (100) plane, and the periphery thereof is embedded in the AlGaInP clad layer 6. In this way, (1
The laser emission on the 1/1) slope can be suppressed, and the characteristics of the semiconductor laser can be further improved. In FIG. 3, the same symbols as those in FIG. 2 indicate the same or corresponding portions.

As described above, according to this embodiment, on the substrate,
Since the clad layer, the active layer, and the clad layer are selectively grown using the insulating film having the stripe-shaped opening extending in the [011] direction as a mask to form the stripe-shaped ridge extending in the [011] direction. It is possible to provide a low-threshold, high-output semiconductor laser that can easily form a semiconductor laser having a ridge with high processing accuracy and that suppresses lateral current spreading.

In this example, AlyGa (1
-y) The case where the current blocking layer made of the InP high resistance layer is used has been described, but the semiconductor laser of this embodiment has a structure in which a blocking layer other than the high resistance layer can be used. By changing the material and structure of the semiconductor laser, the characteristics of a semiconductor laser with a structure in which both sides of the active layer are filled with current blocking layers and a semiconductor laser with a real index guide structure that changes the refractive index on both sides of the active layer are improved. It is also possible. Hereinafter, modifications of the current blocking layer of this embodiment will be described.

For example, as the high resistance layer, Alz Ga (1-
z) As crystals may be used for the block layer. Alz Ga
(1-z) As crystals have high resistance when undoped, and
By mixing oxygen into the crystal, the resistivity can be improved,
Since the higher the Al composition and the higher the oxygen concentration, the higher the resistance, the same effect as the AlyGa (1-y) InP high resistance layer can be obtained.

A high resistance crystal having a lattice constant different from that of the GaAs substrate, for example, a layer made of a material such as Alq In (1-q) As or Fe-doped InP may be used as the block layer.

Further, the reactive current may be blocked by utilizing the band discontinuity between the block layer and the contact layer. For example, a II-VI group crystal (for example, ZnSe)
Etc.) for the blocking layer, II-VI group crystals and p-G
Band discontinuity occurs between the aAs contact layers, and the band discontinuity can block the current.

The block layer may have a multi-layer structure or a superlattice structure, and the light confinement efficiency in the lateral direction can be controlled by adjusting the layer thickness, composition and crystal of each layer. Then, the light emission efficiency of the laser can be improved. For example,
The buried growth layer has a two-layer structure, the lower layer is a p-type GaAs layer, and the upper layer is an n-type GaAs layer. As a result, the p-type block layer, the n-type block layer, and the contact layer are pnp.
It becomes a structure and can block current. Further, similarly to the above, the buried growth layer has a two-layer structure, the lower layer of the block layer is an n-type layer, and the p-type GaAs layer and the n-type layer are formed on this layer.
Two layers including a type GaAs layer may be laminated or a high resistance layer may be provided. Further, a multi-layer structure in which the above-mentioned buried growth layer having a two-layer structure is repeatedly formed twice or more may be used.

When the block layer has a multi-layer structure, a high resistance layer may be used as one layer forming the multi-layer structure. In this case, in order to block the reactive current in this high resistance layer. The layer laminated on or under the high resistance layer may be any semiconductor crystal or any conductivity type (p type, n type, high resistance) semiconductor crystal. For example, as shown in FIG. 7, the side surface of the ridge 50 and the GaAs substrate 1 are covered with AlxGa (1-x).
After covering with the InP high resistance layer 14, AlGaInP / Ga
The ridge 50 may be embedded with an InP multilayer structure. In addition, as a material of the multilayer structure and the superlattice structure,
AlGaInP / GaInP, AlxGa (1-x) InP
(0 ≦ x ≦ 1) / AlvGa (1-v) InP (0 ≦ v ≦
1), AlGaInP / GaAs, AlxGa (1-x) I
nP (0 ≦ x ≦ 1) / AlrGa (1-r) As (0 ≦ r ≦
1), AlrGa (1-r) As (0 ≦ r ≦ 1) / AltG
a (1-t) As (0 ≦ t ≦ 1), Gax1In (1-x1) Asy1
P (1-y1) (0 ≦ x1 ≦ 1, 0 ≦ y1 ≦ 1) / Gax2In (1-x
2) Asy2P (1-y2) (0≤x2≤1, 0≤y2≤1) or the like can be used.

Further, as shown in FIG. 8, a substance other than semiconductor crystals, for example, an insulating film such as polyimide may be used for the block layer. As shown in FIG.
After selective growth, both sides of the ridge 50 are filled with an insulating film 41 made of polyimide or the like, and an electrode 42 is formed on the ridge 50 and the insulating film 41. In the ridge structure of the semiconductor laser of Example 1, the active layer 5 formed in the ridge 50 is covered with the material of the cladding layer and is not damaged in the process after crystal growth.
Even when embedding 1 etc., the active layer 5 is protected,
The characteristics of the semiconductor laser are not deteriorated. Therefore, the range of selection of the material of the current blocking layer is widened, and the degree of freedom in design is improved. For example, as the current blocking layer, a material that can change the refractive index by applying a voltage can be used.

When a material that can selectively remove only the first selection mask on the substrate is used as the second selection mask for the second selection mask, after the ridge growth, the first selection mask is removed.
The second selection mask may be selectively grown on the ridge by using the selection mask of No. 2 as a mask. In such a case, there is an effect that the step of forming the second selection mask can be facilitated.

Example 2. In the first embodiment, after the ridge is formed, the first selection mask on the substrate is removed to form the second selection mask on the (100) plane of the ridge, and the ridge is used as a mask for the current blocking layer. The contact layer was formed on the ridge and the block layer by burying with, and the insulating film was removed. However, as shown in FIG. 9, after forming the ridge 50, the first selection mask (FIG. (Not shown) is removed, and an undoped current block layer 51 made of GaAs or the like or a block layer made of a p-type layer / undoped layer is buried so as to cover the entire ridge 50 so that the surface is flat, and blocks on the ridge 50 Zn is diffused from the surface of the layer 51 to the upper portion of the ridge 50,
A Zn diffusion region 52 is formed in the block layer 51, and then,
An n-side electrode (not shown) and a p-side electrode (not shown) may be formed. There are two types of Zn diffusion steps, vapor phase diffusion and solid phase diffusion. In the case of vapor phase diffusion, an insulating film is formed on the undoped block layer 51, a stripe-shaped opening is formed on the ridge, and Z is formed.
The Zn diffusion region 52 is formed by diffusing n in the vapor phase and diffusing Zn until it reaches the upper portion of the ridge 50. In the case of performing solid phase diffusion, ZnO or Z is formed in stripes only on the upper portion of the ridge 50 on the undoped block layer 51.
A film of nO / SiO (not shown) is formed, and Zn is solid-phase-diffused by applying heat to diffuse Zn to the upper portion of the ridge 50 to form Z.
An n diffusion region 52 is formed. Also in the second embodiment, the same effect as that of the first embodiment can be obtained.

After the Zn diffusion step, in order to improve the contact with the electrode, a step of growing the p-GaAs contact layer 61 on the current block layer 51 is added as shown in FIG. May be.

As the undoped current blocking layer, i-GaInP, i-AlGaInP, i-Al is used.
A crystal that has a high resistance when undoped, such as GaAs, or
A crystal having a high resistance by mixing oxygen may be used. Note that i-GaInP or i-AlGaA
When s is used as the undoped layer, p is made of the same crystal as the undoped layer before growing the p-GaAs contact layer.
A buffer layer having type conductivity is grown. When i-AlGaInP is used, when the ridge 50 is formed, the growth is stopped up to the p-AlGaInP clad layer, and the p-GaInP band discontinuity relaxation layer and p-G are formed.
The aAs cap layer is prevented from growing, the selective mask is removed, the entire ridge 50 is filled with an i-AlGaInP block layer, Zn is diffused to the p-AlGaInP layer above the ridge 50, and then a p-AlGaInP buffer layer is grown. Then, the contact layer is grown, and after the crystal growth, the electrode is provided. This contact layer reduces p-GaAs contact / p-GaIn in order to reduce band discontinuity.
A P-band discontinuous relaxation layer structure is formed. Even when such an undoped block layer is used, the same effect as that of the first embodiment can be obtained.

Although the buried layer has a single-layer structure in the second embodiment, the buried-layer crystal may have a multi-layer structure. For example, p-GaAs / i-GaInP, i
-GaInP / i-AlGaInP, p-GaAs / i
A crystal such as -GaInP / i-AlGaInP may be used. When providing the contact layer,
A p-GaAs layer is used. Even in such a case, the same effect as that of the first embodiment can be obtained.

Example 3. In the first embodiment described above, the contact layer was provided after the current blocking layer was buried on the side surface of the ridge to the same height as the ridge.
As shown in FIG. 5, a double hetero structure is selectively grown to form a ridge 50, the entire ridge 50 is completely filled with the AlGaInP block layer 10, and only the block layer 10 above the ridge 50 is selected until the p-GaAs cap layer 8 is reached. Etch and ridge 50 as shown in FIG. 11 (b).
The p-GaAs contact layer 71 may be formed on the top and the block layer 10. For the etching of the block layer 10, a selective etching solution that stops etching at the p-GaAs cap layer 8 is used. Further, as the block layer, i-GaIn is used.
P, i-AlGaInP, i-GaAs, i-AlGa
A crystal that has a high resistance when undoped such as As, or a crystal that has a high resistance by mixing oxygen may be used. Even in such a case, the same effect as that of the first embodiment can be obtained.

Example 4. FIG. 4 is a cross-sectional view showing the main steps of a method for manufacturing a semiconductor laser according to the fourth embodiment of the present invention. In the figure, the same reference numerals as those in FIG. 1 designate the same or corresponding parts.

In the fourth embodiment, in the process of selective growth of the ridge 50 shown in FIG. 1 in the first embodiment, p-
At the time of growing the AlGaInP cladding layer 6, as shown in FIG. 4, a p-type dopant such as DEZn and H2 Se, SiH are used.
4, n2 type dopants such as Si2 H6 are simultaneously supplied. When selective growth is performed using a (100) GaAs substrate, if a p-type dopant and an n-type dopant are simultaneously supplied, the semiconductor layer formed on the (100) plane is likely to be p-type and is formed by selective growth. (10
A slope inclined with respect to the (0) plane is likely to be n-type. In this case, the steeper the angle of the slope, the more the n-type tends to be formed. Therefore, when the ridge 50 is formed by selective growth (11
/ 1) Slopes such as B-plane are formed, but p-AlGaIn
When the P-clad layer 6 is grown, p-AlGaI is supplied by supplying a dopant with an appropriate p / n ratio selected.
By mixing the p-type dopant and the n-type dopant on the (11/1) B surface of the nP clad layer 6, the (1
The slope such as 1/1) B surface can have high resistance. Then, the current flowing on the slope of the ridge 50 can be reduced, and the efficiency of current injection into the active layer 5 can be improved.

According to the present embodiment as described above, the reactive current flowing through the slope can be reduced and the efficiency of current injection into the active layer can be improved, so that it is lower than that of the semiconductor laser of the first embodiment. It is possible to obtain a semiconductor laser having excellent characteristics that enables high output operation at a threshold value.

In the fourth embodiment, the case where the conductivity type of the substrate is n-type has been described, but the present invention can be applied to the case where the conductivity type of the substrate is p-type and the conductivity type is reversed. In such a case, when a p-AlGaInP lower clad layer used in place of the n-AlGaInP clad layer 4 of Example 4 is grown, a dopant having an appropriate p / n ratio is supplied. As a result, the sloped region of the p-AlGaInP lower cladding layer can have a high resistance, and the same effect as that of the fourth embodiment can be obtained.

Example 5. FIG. 5 is a sectional process drawing by a plane parallel to a (0/11) plane showing a method for manufacturing a semiconductor laser according to a fifth embodiment of the present invention. In the figure, the same symbols as in FIG. 1 are the same or corresponding portions. And 60 is a ridge.

FIG. 6 is a perspective view showing a method of manufacturing a semiconductor laser according to a fifth embodiment of the present invention, and the same reference numerals as those in FIG. 5 denote the same or corresponding parts.

In the first embodiment, the insulating film on the substrate is provided with the stripe-shaped opening extending in the [011] direction, and the ridge having the double hetero structure is selectively grown in the opening. In the fifth embodiment, a stripe-shaped opening extending in the [0/11] direction is provided in the insulating film on the substrate, and a ridge having a double hetero structure is selectively grown in the opening.

Next, a method of manufacturing the semiconductor laser of the fifth embodiment will be described with reference to FIGS. First, Fig. 5 (a)
An insulating film 2 such as SiN or SiO is formed on the (100) surface of the n-GaAs substrate 1 shown in FIG.
The stripe-shaped openings extending in the / 11] direction (so-called reverse mesa direction) are provided to form the first selection mask 2 (FIGS. 5B and 6A). Next, as shown in FIG. 5 (c), using the first selection mask 2, the n-GaAs buffer layer 3, the n-AlGaInP clad layer 4, the GaInP active layer 5 and the p-layer are formed by metalorganic vapor phase epitaxy. —AlGaInP clad layer 6, band discontinuity relaxation layer 7, and p-GaAs cap layer 8 are sequentially grown selectively.

Here, the above-mentioned K. Kamon, S. Takagishi an
d H. Mori, J. Crystal Growth 73 (1985) 73-76, the <0/11> direction (so-called reverse mesa direction) is applied to the SiN film formed on the {100} plane of the GaAs substrate.
Open a striped opening that extends to
When lGaAs is grown, the cross section in the stripe length direction has an isosceles trapezoidal shape, and the cross section in the stripe width direction has a hexagonal shape in which the end portion protrudes outward and the left and right sides are symmetrical. Ridge-like crystal growth, and one of the side faces in the stripe width direction has an upper part of {111} A.
It is known that in the plane, the lower part is a {/ 111} B plane and one of the end faces in the stripe length direction is a {11/1} B plane. Therefore, also in this embodiment, as shown in FIG. 6B, the n-GaAs buffer layer 3 and the n-AlGaI are formed.
nP clad layer 4, GaInP active layer 5, p-AlGa
InP clad layer 6, band discontinuity relaxation layer 7, and p-
The GaAs cap layer 8 sequentially grows so as to cover the surface of the lower layer, and the cross section in the stripe length direction has an isosceles trapezoidal shape, and the cross section in the stripe width direction has a convex end protruding outward. And a stripe-shaped ridge 60 having a hexagonal shape with left and right symmetry is formed. It should be noted that compared to the growth of the {100} plane to the plane, {111} A
The crystal growth on the plane and the plane such as {/ 111} B plane grows at a very slow rate. Therefore, the thickness of each layer constituting the ridge 60 laminated on the {111} A plane and the {/ 111} B plane which are the side surfaces of the ridge 60 is smaller than the thickness in the direction perpendicular to the (100) plane. Become very thin. The cross-sectional structure at this time is as shown in FIG. 5C. Both ends of the active layer 5 in the ridge stripe width direction are covered with the cladding layer 6, and the entire active layer 5 is embedded in the ridge 60 along the ridge stripe. Is arranged as.

Thereafter, as in the first embodiment, the insulating film 2 is formed.
Is removed, and a second selection mask 9 is formed on the ridge 60. Using this as a mask, the current block layer 10 is grown so as to fill the ridge 60 (FIGS. 5D and 6C).
(c)), After removing the selective mask 9, a p-GaAs contact layer 11 is grown and an n-side electrode 12 is formed on the back surface side of the substrate 1.
In addition, a p-side electrode 13 is formed on the surface of the contact layer 11 (FIGS. 5 (e) and 6 (d)), and finally, cleavage is performed at a portion where the active layer 5 exists to form a semiconductor laser diode element. (FIG. 6 (e)).

Also in the semiconductor laser of Example 5, as described above, since the crystal growth rate is slow on the {111} A plane and the {/ 111} B plane, the active layer is formed on the side surface of the cladding layer 4. Since 5 is laminated only in a very thin thickness, in the active layer 5 formed in the ridge side surface region,
Almost no laser light is generated. If it is desired to make the active layer 5 formed on the side surface of the ridge 60 as thin as possible, the active layer may be grown under the condition that migration is likely to occur as in the first embodiment. The active layer 5 and the p-AlGaInP clad layer 6 formed on the side surface of the ridge 60 of the clad layer 4 are sufficiently thin,
Since the resistance is sufficiently high, the n-AlGa of the ridge 60 is
The reactive current that tries to pass through the side surface of the InP clad layer 4 is blocked by the high resistance active layer 5 and the p-AlGaInP clad layer 6. As described in the fourth embodiment, by supplying the p-type dopant and the n-type dopant with an appropriate p / n ratio selected during the growth of the cladding layer 6, the side surface of the ridge 60 can be more reliably made to have a high resistance. You may do it.

Also in this embodiment, the n-type cladding layer 3 and the active layer 5 are formed on the substrate 1 by using the first selection mask having the stripe-shaped opening extending in the [0/11] direction as a mask. , And the p-type cladding layer 6 are selectively grown to form stripe-shaped ridges 6 extending in the [0/11] direction.
Since 0 is formed, as in the first embodiment,
It is possible to provide a low-threshold, high-power semiconductor laser in which a ridge with high processing accuracy can be easily formed without etching, and lateral current spread is suppressed.

Example 6. FIG. 12 is a sectional process drawing by a plane parallel to a (001) plane showing a method for manufacturing a semiconductor laser according to a sixth embodiment of the present invention. In the figure, the same reference numerals as those in FIG. 1 designate the same or corresponding portions. And 70 is a ridge.

FIG. 13 is a perspective view showing a method of manufacturing a semiconductor laser according to the sixth embodiment of the present invention.
The same reference numerals as in FIG.

In the first embodiment, the insulating film on the substrate is provided with the stripe-shaped opening extending in the [011] direction, and the ridge having the double hetero structure is selectively grown in the opening. In Example 6, stripe-shaped openings extending in the [001] direction were provided in the insulating film on the substrate, and ridges having a double hetero structure were selectively grown in the openings.

Next, a method of manufacturing the semiconductor laser of the sixth embodiment will be described with reference to FIGS. First, FIG.
Si is formed on the (100) plane of the n-GaAs substrate 1 shown in (a).
An insulating film such as N or SiO is formed, and a stripe-shaped opening extending in the [001] direction is provided by photolithography.
The selection mask 2 is formed. (FIG. 12 (b), FIG. 13 (a)).

Next, as shown in FIG. 12C, n-GaA is formed by metalorganic vapor phase epitaxy using the selective mask 2.
s buffer layer 3, n-AlGaInP clad layer 4, G
aInP active layer 5, p-AlGaInP clad layer 6,
Band discontinuity relaxation layer 7 and p-GaAs cap layer 8
To grow selectively.

At this time, as shown in FIG. 13B, n-
The GaAs buffer layer 3, the n-AlGaInP clad layer 4, the GaInP active layer 5, the p-AlGaInP clad layer 6, the band discontinuity relaxation layer 7, and the p-GaAs cap layer 8 are crystal-grown in order to cover the surface of the lower layer. do it,
A rectangular parallelepiped striped ridge 70 is formed.
It should be noted that, compared with the growth on the plane of the {100} plane, {01
Crystal growth on a plane such as the 0} plane grows at a very slow rate. Therefore, the thickness of each layer forming the ridge 70 in the width direction of the ridge stripe is much smaller than the thickness in the direction perpendicular to the (100) plane. The sectional structure at this time is shown in Fig. 1.
2 (c), both ends of the active layer 5 in the ridge stripe width direction are covered with the cladding layer 6 and the like, and the entire active layer 5 is arranged so as to be embedded in the ridge 70 along the ridge stripe.

After that, the insulating film 2 is formed as in the first embodiment.
Is removed, an insulating mask 9 is formed on the ridge 70,
Using this as a mask, the current block layer 10 is grown so as to fill the ridge 70 (FIGS. 12D and 13C).
(c)) After removing the insulating mask 9, a p-GaAs contact layer 11 is grown, and an n-type electrode 12 is formed on the back surface side of the substrate 1.
Further, the p-type electrode 13 is formed on the surface of the contact layer 11 (FIGS. 12 (e) and 13 (d)), and finally, cleavage is performed at the portion where the active layer 5 is present to form a semiconductor laser diode element. (FIG. 13 (e)).

Also in the semiconductor laser of the sixth embodiment, as described above, the active layer 5 is laminated only on the side surface of the n-type cladding layer 4 in the ridge stripe width direction with a very small thickness, so that the ridge 70 is formed. Almost no laser light is generated in the active layer 5 formed in the side surface region of the. If it is desired to make the active layer 5 formed on the side surface of the ridge 70 as thin as possible, the active layer may be grown under the condition that migration is likely to occur as in the first embodiment. In addition, the active layer 5 formed on the side surface of the clad layer 4
Since the p-AlGaInP clad layer 6 is sufficiently thin and the resistance is sufficiently high, the n-Al of the ridge 70 is formed.
The reactive current that tries to pass near the side surface of the GaInP clad layer 4 is caused by the high resistance active layer 5 and p-AlGaI.
It is blocked by the nP clad layer 6. As described in the fourth embodiment, by supplying the p-type dopant and the n-type dopant with an appropriate p / n ratio selected during the growth of the p-type cladding layer 6, the ridge 70 can be more reliably formed.
You may make it the high side surface.

Also in this embodiment, the clad layer 4, the active layer 5, and the clad layer are formed on the substrate 1 by using the selective mask made of the insulating film having the stripe-shaped opening extending in the [001] direction. Since the layer 6 is selectively grown to form the stripe-shaped ridge 70 extending in the [001] direction, a ridge with high processing accuracy can be easily formed without etching, as in the first embodiment. It is possible to provide a semiconductor laser with a low threshold and a high output, which can suppress the spread of the current in the lateral direction.

In the sixth embodiment, the case where the stripe direction of the opening on the insulating film is [001] has been described. However, even if the stripe direction is [010], the ridge is selectively grown in a rectangular parallelepiped shape. Therefore, the present invention can be applied to the case where the stripe direction is the [010] direction and has the same effect as that of the sixth embodiment.

Example 7. 14 is a sectional view showing the structure of a semiconductor laser according to the seventh embodiment of the present invention. In the figure, the same reference numerals as those in FIG. 1 denote the same or corresponding portions, and 20 denotes a window structure.

In the first embodiment, the cleavage for forming the laser end face is performed at the portion where the active layer exists. However, in the semiconductor laser of the present Example 7, the length of the ridge is previously set to a predetermined length that matches the length of the laser cavity, and cleavage for laser end face formation or dry etching for end face formation is performed. This is performed in a region that does not include the active layer, which is separated from the end of the active layer in the stripe length direction by a predetermined distance in the direction.

When the cleavage is carried out in this way, the cross section in the laser cavity length direction has a p-AlGa end face in the cavity length direction of the active layer 5 of the semiconductor laser as shown in FIG.
It is covered with the InP clad layer 6 and further has a shape in which the vicinity of the cavity end face of the semiconductor laser is covered with the current block layer 10. At this time, since the band gap of the p-AlGaInP clad layer 7 and the block layer 10 made of the AlGaInP high resistance layer is larger than that of GaInP which is the active layer 5, the vicinity of the cavity end face is the window structure 20, that is, the end face region. The structure makes it difficult to absorb laser light. This makes it possible to obtain a semiconductor laser that is unlikely to cause edge breakage even during high-power operation.

As described above, in the seventh embodiment, the same effect as that of the above-described embodiment is obtained, and the cleavage is performed in the region not including the active layer 5, so that the high output having the window structure can be easily provided. An operable semiconductor laser can be obtained.

Example 8. FIG. 15 is a sectional view showing the structure of a semiconductor laser according to the eighth embodiment of the present invention. In the figure, the same reference numerals as those in FIG. 5 denote the same or corresponding portions, and 21 denotes a window structure.

In the fifth embodiment, the cleavage for forming the laser end face is performed in the portion where the active layer is present. However, in the semiconductor laser of Example 8, the length of the ridge is previously set to a predetermined length that matches the length of the laser cavity, and cleavage for forming the laser end face or dry etching for forming the end face is performed. This is performed in a region that does not include the active layer, which is separated from the end of the active layer in the stripe length direction by a predetermined distance in the direction.

When the cleavage is performed in this way, the cross section in the direction of the laser cavity length has a p-AlGa end face in the cavity length direction of the active layer 5 of the semiconductor laser as shown in FIG.
It is covered with the InP clad layer 6, and further has a shape in which the vicinity of the cavity end face of the semiconductor laser is covered with the block layer 10. At this time, the block layer 10 including the p-AlGaInP clad layer 6 and the AlGaInP high resistance layer
Has a forbidden band width larger than that of GaInP that is the active layer 5, so that the vicinity of the end face of the resonator has a window structure 21, that is, a structure in which laser light is hard to be absorbed in the end face region. This makes it possible to obtain a semiconductor laser that is unlikely to cause edge breakage even during high-power operation.

As described above, in the eighth embodiment, the same effect as that of the fifth embodiment is obtained, and the cleavage is performed in the region not including the active layer 5, so that the window structure is easily provided. A semiconductor laser capable of output operation can be obtained.

Example 9. FIG. 16 is a sectional view showing the structure of a semiconductor laser according to the ninth embodiment of the present invention. In the figure, the same reference numerals as those in FIG. 12 denote the same or corresponding portions, and 22 denotes a window structure.

In the sixth embodiment, the cleavage for forming the laser end face is performed at the portion where the active layer exists. However, in the semiconductor laser of the present Example 4, the length of the ridge is previously set to a predetermined length that matches the length of the laser cavity, and cleavage for laser end face formation or dry etching for end face formation is performed. This is performed in a region that is apart from the end portion of the active layer in the stripe length direction in a predetermined distance in the direction and does not include the active layer.

When the cleavage is carried out in this way, the cross section in the laser cavity length direction has a p-AlGa end portion in the cavity length direction of the active layer 5 of the semiconductor laser as shown in FIG.
It is covered with the InP clad layer 6, and further has a shape in which the vicinity of the cavity end face of the semiconductor laser is covered with the block layer 10. At this time, the block layer 10 including the p-AlGaInP clad layer 6 and the AlGaInP high resistance layer
Has a forbidden band width larger than that of GaInP that is the active layer 5, so that the vicinity of the cavity end face has a window structure 22, that is, a structure in which laser light is hard to be absorbed in the end face region. This makes it possible to obtain a semiconductor laser that is unlikely to cause end face destruction even during high-power operation.

As described above, in the ninth embodiment, the same effect as that of the sixth embodiment is obtained, and the cleavage is performed in the region not including the active layer 5, so that the window structure can be easily provided. A semiconductor laser capable of output operation can be obtained.

In the seventh to ninth embodiments, the case where the AlGaInP high resistance layer is used as the block layer has been described, but the block layer has a larger forbidden band width than that of the active layer and the block layer. Other materials having properties that can be used as the above may be used, and the same effects as those of the seventh to ninth embodiments can be obtained.

Example 10. FIG. 17 is a perspective view (FIGS. 17 (a) and (b)) showing the main steps of the method for manufacturing a semiconductor laser according to the tenth embodiment of the present invention, and a sectional view taken along the line I-I of FIG. 17 (b). 17 (c), and the same reference numerals as those in FIG. 12 indicate the same or corresponding portions in FIG.

In the ninth embodiment, the semiconductor laser having the window structure is formed so that the end face of the ridge in the cavity length direction is filled with the block layer. The semiconductor laser of the tenth embodiment is shown in FIG. As shown in FIG. 17, when the ridge 70 is formed in advance so that the stripe length becomes the same as the resonator length, and the current block layer 10 is formed, FIG.
As shown in (a), only the side surface of the ridge 70 is filled with the block layer 10 using the selection mask 9 as a mask, and the ridge 7 is formed.
The end face in the stripe length direction of 0 is not filled with the block layer 10, and then the insulating mask 9 is removed as shown in FIG. 17 (b), and the contact layer 11, the n-side electrode 12,
The p-side electrode 13 is formed to form a semiconductor laser.

In the semiconductor laser thus formed, as described above, the end face of the ridge 70 formed by selective growth so as to extend in the [001] direction or the [010] direction is in the cavity length direction. Since it is perpendicular to this, this end face can be used as a laser end face. Therefore, in this embodiment, it is possible to form the laser end surface without performing cleavage. Further, as shown in FIG. 17C, since the end face in the cavity length direction of the active layer 5 is covered with the p-AlGaInP cladding layer 6 having a larger forbidden band width than the active layer 5, this portion has a window structure. Function as.

As described above, according to this embodiment, it is possible to easily provide a semiconductor laser having a window structure without performing cleavage.

Although the case where GaInP is used as the active layer has been described in each of the above embodiments, other materials may be used. As the material of the other active layer, AlxGa1-x InP (0≤x≤1) is preferable.

Further, although the case where the active layer composed of a single layer is used has been described in the above embodiment, the structure of the active layer is a multi quantum well (MQW) structure or a double quantum well (Double Quantum Well). It may be a Quantum Well (DQW) structure or a single quantum well (SQW) structure. In the vicinity of the active layer, the separated confinement hetero (S
eparate Confinement Heterostructure (SCH) structure, active layer and multi quantum barrier (M)
It may be a structure in combination with a QB) structure. Further, strain may be applied to the active layer having the quantum well structure or the superlattice structure such as the MQB structure. Even in such a case, the same effect as that of the first embodiment can be obtained.

Further, in each of the above-mentioned embodiments, the material of the semiconductor laser is AlGaInP which is a visible light laser.
The case where the n-GaAs substrate is used as the material of the Al series is explained, but a short-wave type A other than the AlGaInP material is used.
The present invention can also be applied to 1GaAs-based and long-wave InP-based materials, and has the same effect as each of the above-described embodiments.

Furthermore, the present invention can be applied to a semiconductor laser having a conductivity type opposite to that of each of the above-mentioned embodiments, and has the same effect as each of the above-mentioned embodiments. At this time, as shown in the second embodiment, when it is necessary to diffuse impurities into the block layer above the ridge to make contact with the ridge, the contact layer is made of n-GaA.
s or n-Ge is used, Se, Si instead of Zn
It is sufficient to use an n-type dopant such as.

In each of the above embodiments, the surface of the semiconductor substrate is the (100) plane, and the ridge stripe directions are the [011] direction, the [0/11] direction, the [001] direction and the [010] direction. In the present invention, the substrate surface is equivalent to the (100) plane, that is, {10
0}, the ridge stripe direction is the <011> direction,
The present invention can be applied to the case of the <0/11> direction, the <001> direction, and the <010> direction, and in such a case, the same effect as that of each of the above-described embodiments can be obtained.

Further, in each of the above embodiments, the case where the {100} surface is used as the ridge stripe forming surface of the substrate has been described, but the present invention is directed to the case where the ridge stripe forming surface of the substrate is the {100} surface. The present invention can be applied even when it is tilted, and in such a case, the shape of the ridge stripe changes depending on the tilt angle, but the same effect as each of the above-mentioned embodiments is obtained.

[0106]

As described above, according to the method of manufacturing a semiconductor laser of the present invention, the double hetero structure including the first conductivity type cladding layer, the active layer and the second conductivity type cladding layer on the {100} plane of the substrate. The structure is selectively grown, the surfaces of the active layer and the first conductivity type clad layer are covered with the second conductivity type clad layer, the cross section in the stripe width direction is a forward mesa shape, and the cross section in the stripe length direction is Since the ridge stripe, which is a bilaterally symmetrical hexagonal shape, is formed, the processing accuracy of the ridge is improved, the spread of the current in the width direction of the resonator is suppressed, the threshold value is low, and high output operation is possible. There is an effect that a possible semiconductor laser can be easily provided.

According to the method of manufacturing a semiconductor laser of the present invention, the double hetero structure including the first conductivity type cladding layer, the active layer and the second conductivity type cladding layer is selectively grown on the {100} plane of the substrate. Then, the surfaces of the active layer and the first conductivity type clad layer are covered with the second conductivity type clad layer, and the cross section in the stripe width direction has a symmetrical hexagonal shape, and the cross section in the stripe length direction is the same. Since a ridge stripe having a trapezoidal shape is formed, the processing accuracy of the ridge is improved, the spread of the current in the width direction of the resonator is suppressed, the threshold value is low, and high-power operation is possible. There is an effect that a laser can be easily provided.

Further, according to the method of manufacturing a semiconductor laser of the present invention, the double hetero structure including the first conductivity type clad layer, the active layer and the second conductivity type clad layer is selectively grown on the {100} plane of the substrate. Then, since the rectangular parallelepiped ridge stripe in which the surfaces of the active layer and the first conductivity type clad layer are covered with the second conductivity type clad layer is formed, the processing accuracy of the ridge is improved and the resonator is improved. There is an effect that the spread of the current in the width direction is suppressed, and a semiconductor laser having a low threshold value and capable of high output operation can be easily provided.

According to the method of manufacturing a semiconductor laser of the present invention, in the method of manufacturing a semiconductor laser described above,
After forming the ridge stripe, the selection mask is removed, and a current blocking layer made of a material having a band gap larger than that of the active layer is formed on at least the {100} plane of the substrate around the ridge, at least the ridge. A semiconductor laser having a window structure and capable of high-power operation is formed by embedding to a height reaching the height and forming the laser end face of the semiconductor laser in a region having no active layer of the ridge stripe. There is an effect that can be easily provided.

According to the method of manufacturing a semiconductor laser of the present invention, in the method of manufacturing a semiconductor laser described above,
Since the end face of the ridge is the end face of the resonator of the semiconductor laser, it is possible to easily provide a semiconductor laser having a window structure and capable of high-power operation.

According to the method of manufacturing a semiconductor laser of the present invention, in the method of manufacturing a semiconductor laser described above,
As a material forming the active layer, a material that migrates more easily than other materials forming the ridge is used, and the selective growth of the ridge is performed under the condition that the material forming the ridge easily migrates. The formation of the active layer on the side surface of the first conductivity type cladding layer can be prevented, and the characteristics of the semiconductor laser can be improved.

According to the method of manufacturing a semiconductor laser of the present invention, in the method of manufacturing a semiconductor laser described above,
The step of selectively growing the second conductivity type clad layer using the second conductivity type clad layer as the p-type clad layer, the p-type dopant and the n-type dopant being formed on the ridge side surface of the second conductivity type clad layer. Since it is performed in an atmosphere in which a mixed gas is supplied at a predetermined ratio so that the resistance becomes high, the region near the first conductivity type clad layer on the side surface of the ridge can have higher resistance, and the reactive current can be surely obtained. Can be reduced and the characteristics of the semiconductor laser can be improved.

According to the method of manufacturing a semiconductor laser of the present invention, in the method of manufacturing a semiconductor laser described above,
In the step of selectively growing the first conductivity type clad layer using the first conductivity type clad layer as a p-type clad layer, a p-type dopant and an n-type dopant are added to a region near the ridge side surface of the first conductivity type clad layer. Since it was performed in an atmosphere in which a gas mixed at a predetermined ratio was supplied so as to have a high resistance,
The region near the first conductivity type cladding layer on the side surface of the ridge can have a higher resistance, the reactive current can be surely reduced, and the characteristics of the semiconductor laser can be improved.

Further, according to the semiconductor laser of the present invention, the first conductivity type clad layer disposed on the {100} plane of the first conductivity type semiconductor substrate and the {100} surface of the first conductivity type clad layer. A double heterostructure composed of an active layer disposed on the {} plane and a second conductivity type clad layer disposed so as to cover the active layer and the first conductivity type clad layer. Since it has a stripe-shaped ridge extending in the <011> direction, which is a normal mesa shape, it is possible to suppress the spread of current in the width direction of the resonator, the threshold value is low, and high output operation is possible. There is an effect that a semiconductor laser can be easily provided.

Further, according to the semiconductor laser of the present invention, the first conductivity type clad layer disposed on the {100} plane of the first conductivity type semiconductor substrate and the {100} surface of the first conductivity type clad layer. A double heterostructure composed of an active layer disposed on the {} plane and a second conductivity type clad layer disposed so as to cover the active layer and the first conductivity type clad layer. Bilateral hexagonal shape <0
Since it has a stripe-shaped ridge extending in the / 11> direction, it is possible to suppress the spread of current in the width direction of the resonator, to easily form a semiconductor laser with a low threshold value and high output operation. There is an effect that can be provided.

Further, according to the semiconductor laser of the present invention, the first conductivity type clad layer disposed on the {100} plane of the first conductivity type semiconductor substrate and the {100} surface of the first conductivity type clad layer. A double heterostructure composed of an active layer disposed on the {} plane and a second conductivity type clad layer disposed so as to cover the active layer and the first conductivity type clad layer. Since it has a rectangular stripe-shaped ridge extending in the <001> direction or the <010> direction, it is possible to suppress the spread of the current in the width direction of the resonator, the threshold value is low, and the high output is obtained. There is an effect that an operable semiconductor laser can be easily provided.

In the semiconductor laser, the second conductivity type cladding layer is arranged so as to cover the end face of the ridge in the stripe length direction, and the periphery of the ridge has a larger forbidden band width than the active layer. Since it is embedded with the current blocking layer, there is an effect that a semiconductor laser having a window structure and capable of high-power operation can be easily provided.

Further, according to the semiconductor laser of the present invention, the region near the first conductivity type cladding layer on the side surface of the ridge has a high resistance, so that the spread of the current in the cavity width direction is further suppressed. As a result, a semiconductor laser having a low threshold and capable of high-power operation can be easily provided.

According to the semiconductor laser of the present invention, in the above semiconductor laser, the end face of the ridge constitutes a resonator end face, and the second conductivity type cladding layer is at the resonator end face of the semiconductor laser. Since the active layer and the first-conductivity-type cladding layer are disposed so as to cover the active layer and the first-conductivity-type cladding layer, it is possible to easily provide a semiconductor laser having a window structure and capable of high-power operation.

[Brief description of drawings]

FIG. 1 is a sectional view showing a method for manufacturing a semiconductor laser according to a first embodiment of the present invention.

FIG. 2 is a perspective view showing a method for manufacturing a semiconductor laser according to the first embodiment of the present invention.

FIG. 3 is a cross-sectional view showing the growth condition dependency of the growth rate of the active layer on the (111) plane according to the first example of the present invention.

FIG. 4 is a schematic sectional view for explaining p / n simultaneous doping when forming a ridge according to the first embodiment of the present invention.

FIG. 5 is a sectional view showing a method for manufacturing a semiconductor laser according to a fifth embodiment of the present invention.

FIG. 6 is a perspective view showing a method for manufacturing a semiconductor laser according to a fifth embodiment of the present invention.

FIG. 7 is a cross-sectional view for explaining the structure of a semiconductor laser provided with a current blocking layer having a multi-layered structure according to a modification of the first embodiment of the present invention.

FIG. 8 is a cross-sectional view for explaining the structure of a semiconductor laser using an insulating film as a current blocking layer according to a modification of the first embodiment of the present invention.

FIG. 9 is a sectional view showing the structure of a semiconductor laser according to a second embodiment of the present invention.

FIG. 10 is a sectional view showing a structure of a semiconductor laser according to a modification of the second embodiment of the present invention.

FIG. 11 is a cross-sectional view showing the main steps of a method for manufacturing a semiconductor laser according to the third embodiment of the present invention.

FIG. 12 is a cross sectional view for illustrating the method for manufacturing the semiconductor laser according to the sixth embodiment of the present invention.

FIG. 13 is a perspective view for explaining the method for manufacturing the semiconductor laser according to the sixth embodiment of the present invention.

FIG. 14 is a cross sectional view in the cavity length direction showing the structure of a semiconductor laser according to a seventh embodiment of the present invention.

FIG. 15 is a sectional view in the cavity length direction showing the structure of a semiconductor laser according to an eighth embodiment of the present invention.

FIG. 16 is a sectional view in the cavity length direction showing the structure of a semiconductor laser according to a ninth embodiment of the present invention.

FIG. 17 is a perspective view showing the main steps of the method for manufacturing a semiconductor laser according to the tenth embodiment of the present invention (FIG. 17 (a),
(b)), and a sectional view in the cavity length direction showing the structure (Fig. 17).
(c)).

FIG. 18 is a cross-sectional view showing a conventional method for manufacturing a semiconductor laser.

[Explanation of symbols]

1 n-GaAs substrate, 2 first selection mask, 3 n
-GaAs buffer layer, 4n-AlGaInP clad layer, 5,5a GaInP active layer, 6p-AlGa
InP clad layer, 6a, 6b First and second p-Al
GaInP clad layer, 7 p-GaInP band discontinuity relaxation layer, 8 p-GaAs cap layer, 9 second selection mask, 9a selection mask, 10 high resistance current blocking layer, 10a n-GaAs current blocking layer, 11 p
-GaAs contact layer, 12n side electrode, 13, 42
p-side electrode, 14 high resistance layer, 15 p-GaInP etching stopper layer, 16 AlGaInP / GaIn
P multilayer structure, 20, 21, 22 window structure part, 41 insulating film, 50, 60, 70 ridge, 51 undoped G
aAs block layer, 52 Zn diffusion region, 61 p-G
aAs contact layer, 71 p-GaAs contact layer.

Claims (14)

[Claims] 1. A <0} layer on the {100} plane of a first conductivity type substrate.
11) forming a selective mask having a stripe-shaped opening extending in the <11> direction, and using the selective mask as a mask, a first conductive type clad layer, an active layer, and a second conductive type clad layer are formed on the {100} plane of the substrate. A double heterostructure including a layer is selectively grown, the surfaces of the active layer and the first conductivity type cladding layer are covered with the second conductivity type cladding layer, and the cross section in the stripe width direction has a forward mesa shape And a step of forming a ridge stripe having a hexagonal cross-section in the longitudinal direction which is bilaterally symmetric. 2. A <0} film is formed on the {100} plane of the first conductivity type substrate.
Forming a selection mask having a stripe-shaped opening extending in the / 11> direction, and using the selection mask as a mask, a first conductivity type cladding layer, an active layer, and a second conductivity type are formed on the {100} plane of the substrate. A double heterostructure including a clad layer is selectively grown, and the surfaces of the active layer and the first conductivity type clad layer are covered with the second conductivity type clad layer, and the cross section in the stripe width direction is a symmetrical hexagonal shape. And a step of forming a ridge stripe whose cross section in the stripe length direction has an isosceles trapezoidal shape. 3. A <0} film is formed on the {100} plane of the first conductivity type substrate.
Forming a selective mask having a stripe-shaped opening extending in the <01> direction or <010> direction, and using the selective mask as a mask, a first conductivity type clad layer, an active layer, Step of selectively growing a double heterostructure including a second conductivity type cladding layer to form a rectangular parallelepiped ridge stripe in which the surfaces of the active layer and the first conductivity type cladding layer are covered with the second conductivity type cladding layer. And a method of manufacturing a semiconductor laser. 4. The method for manufacturing a semiconductor laser according to claim 1, wherein after the ridge stripe is formed, the selection mask is removed, and the periphery of the ridge is on the {100} surface of the substrate. A step of embedding a current blocking layer made of a material having a band gap larger than that of the active layer to a height reaching at least the height of the ridge, and forming a cavity facet of the semiconductor laser in the active layer of the ridge stripe. A method for manufacturing a semiconductor laser, which is characterized in that it is formed in a region that does not have a. 5. The method of manufacturing a semiconductor laser according to claim 3, wherein after forming the ridge stripe, an end surface of the ridge is used as an end surface of a cavity of the semiconductor laser. 6. The method for manufacturing a semiconductor laser according to claim 1, wherein a material that is more likely to migrate than another material that forms the ridge is used as a material forming the active layer, A method of manufacturing a semiconductor laser, characterized in that the step of selectively growing the ridge is carried out under the condition that the material forming the ridge easily migrates. 7. The method for manufacturing a semiconductor laser according to claim 1, wherein the second conductivity type cladding layer is a p-type cladding layer, and the second conductivity type cladding layer is selectively grown. Is p
Manufacturing of a semiconductor laser, wherein a type dopant and an n-type dopant are performed in an atmosphere in which a gas mixed with a predetermined ratio so that the second conductivity type clad layer formed on the side surface of the ridge has a high resistance is supplied. Method. 8. The method of manufacturing a semiconductor laser according to claim 1, wherein the first conductivity type cladding layer is a p-type cladding layer, and the first conductivity type cladding layer is selectively grown. Is p
A method of manufacturing a semiconductor laser, wherein a type dopant and an n-type dopant are performed in an atmosphere in which a gas mixed with a predetermined ratio so that the ridge side surface region of the first conductivity type cladding layer has a high resistance is supplied. 9. A first conductivity type clad layer disposed on the {100} plane of the first conductivity type semiconductor substrate, and an active layer disposed on the {100} plane of the first conductivity type clad layer. A cross-section in the stripe width direction having a forward mesa shape, which has a double hetero structure composed of the active layer and the second-conductivity-type clad layer arranged so as to cover the first-conductivity-type clad layer <011 A semiconductor laser having a stripe-shaped ridge extending in the <> direction. 10. A first conductivity type clad layer disposed on the {100} surface of the first conductivity type semiconductor substrate, and an active layer disposed on the {100} surface of the first conductivity type cladding layer. ,
The cross-section in the stripe width direction has a bilaterally symmetrical hexagonal shape, which has a double hetero structure composed of the active layer and the second-conductivity-type cladding layer arranged so as to cover the first-conductivity-type cladding layer. A semiconductor laser having a stripe-shaped ridge extending in the <0/11> direction. 11. A first conductivity type clad layer disposed on the {100} plane of the first conductivity type semiconductor substrate, and an active layer disposed on the {100} plane of the first conductivity type clad layer. ,
A <001> direction having a rectangular cross-section in the stripe width direction, which has a double hetero structure composed of the active layer and a second-conductivity-type cladding layer arranged so as to cover the first-conductivity-type cladding layer. Alternatively, a semiconductor laser having a stripe-shaped ridge extending in the <010> direction. 12. The semiconductor laser according to claim 9, wherein the second-conductivity-type cladding layer is arranged so as to cover an end face of the ridge in the stripe length direction, and the periphery of the ridge is A semiconductor laser, wherein the semiconductor laser is embedded in a current block layer having a band gap larger than that of the active layer. 13. The semiconductor laser according to claim 9, wherein a region near the first conductivity type cladding layer on the side surface of the ridge has a high resistance. 14. The semiconductor laser according to claim 11, wherein the ridge end face constitutes a cavity end face, and the second conductivity type clad layer forms the active layer and the active layer at the cavity end face of the semiconductor laser. A semiconductor laser arranged so as to cover the first conductivity type cladding layer.