JPH08213695A - Semiconductor laser and its manufacture - Google Patents

Abstract

PURPOSE: To realize a semiconductor laser having end-face current non-injection structure by a simple manufacturing process while preventing a defect by using a p-type GaAs layer as a cap layer. CONSTITUTION: An n-type GaAs layer 2, an n-type AlGaInP layer 3, an active layer 4, a p-type AlGaInP layer 5, a p-type GaInP layer 6 and p-type GaAs layer 7 are laminated successively on an n-type GaAs substrate 1, the p-type GaAs layer 7, the p-type GaInP layer 6 and the p-type AlGaInP layer 5 are patterned in a striped shape, n-type GaAs layers 8 are laminated on both side sections of the p-type GaAs layer 7, and a p-side electrode 9 s formed on these p-type GaAs layer 7 and n-type GaAs layer 8. The carrier concentration of the p-type GaAs layer 7 in a current injection region is set at a value, where the p-side electrode 9 is brought into ohmic-contact, such as approximately 2×10<19> cm<-3> , and the carrier concentration of the p-type GaAs layer 7 in a current non-injection region is set at a value, where the p-side electrode 9 is not brought into ohmic-contact, such as a value less than 1×10<19> cm<-3> .

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor laser and a manufacturing method thereof, and more particularly to a semiconductor laser having a so-called end face current non-injection structure and a manufacturing method thereof.

[0002]

2. Description of the Related Art One of the factors that hinders the high output of semiconductor lasers is the temperature rise due to the increase in photon density near the end face of a laser resonator. A semiconductor laser having an end face current non-injection structure is intended to solve this problem, in which a current injected near the end face of the laser resonator is reduced to suppress recombination of electrons and holes therein, The temperature rise is suppressed by decreasing the photon density near the end face,
It is intended to increase the output.

Conventionally, as a semiconductor laser having this end face current non-injection structure, a gain guide type A as shown in FIG.
The lGaInP-based semiconductor laser is known (199
Proceedings of the 1st Spring Meeting of the Japan Society of Applied Physics 9p-ZM-
5). As shown in FIG. 7, in this AlGaInP-based semiconductor laser, an n-type GaInP layer 102 as a buffer layer, an n-type AlGaInP layer 103 as an n-type cladding layer, and an undoped as an active layer are provided on an n-type GaAs substrate 101. A GaInP layer 104, a p-type AlGaInP layer 105 as a p-type cladding layer, a p-type GaInP layer 106 as a contact layer, and a p-type GaAs layer 107 as a cap layer are sequentially stacked. here,
The p-type GaAs layer 107 is patterned in a stripe shape, and its both ends in the cavity length direction are terminated before the both end faces of the laser cavity, respectively. The p-type GaI in the peripheral portion of the p-type GaAs layer 107
A SiO ₂ film 108 is provided on the nP layer 106. Then, these p-type GaAs layer 107 and Si
A p-side electrode 109 made of Au—Cr is formed on the O ₂ film 108.
Is provided. On the other hand, an n-side electrode 110 made of Au—Sn—Cr is provided on the back surface of the n-type GaAs substrate 101.

In the AlGaInP type semiconductor laser shown in FIG. 7, the stripe-shaped p-type GaAs layer 10 is used.
A portion 7 is a current injection region, and a portion between both ends of the p-type GaAs layer 107 and both end faces of the laser resonator in the cavity length direction is a current non-injection region.

Further, as a semiconductor laser having an end face current non-injection structure, a refractive index guided Al as shown in FIG.
A GaInP-based semiconductor laser is also known (1991).
Proceedings of the Autumn Meeting of the Japan Society of Applied Physics 30p-D-1
0). As shown in FIG. 8, in this AlGaInP-based semiconductor laser, an n-type GaInP layer 202 as a buffer layer, an n-type AlGaInP layer 203 as an n-type cladding layer, and an undoped AlGaInP as an active layer are provided on an n-type GaAs substrate 201. A layer 204, a p-type AlGaInP layer 205 as a p-type cladding layer, and a p-type GaInP layer 206 as a contact layer are sequentially stacked. Here, the portion of the p-type AlGaInP layer 205 excluding the lower layer portion and the p-type GaInP layer 206 are patterned in a stripe shape. Furthermore, these p
-Type AlGaInP layer 205 and p-type GaInP layer 20
An n-type GaAs layer 20 as a current blocking layer is provided on
7 are stacked. The n-type GaAs layer 207 is provided with stripe-shaped openings 207a. here,
Both ends of this opening 207a in the cavity length direction are terminated before both end faces of the laser cavity. Further, these p-type GaInP layer 206 and n-type GaA
A p-type GaAs layer 208 as a cap layer is laminated on the s layer 207. A p-side electrode 209 made of Au—Cr is provided on the p-type GaAs layer 208, and A is formed on the back surface of the n-type GaAs substrate 201.
An n-side electrode 210 made of u-Sn-Cr is provided.

In the AlGaInP based semiconductor laser shown in FIG. 8, the stripe-shaped opening 207a of the n-type GaAs layer 207 is a current injection region, and both ends of the opening 207a in the cavity length direction and the laser resonator. A portion between the both end faces is a current non-injection region.

[0007]

However, in the conventional AlGaInP based semiconductor laser shown in FIG. 7 described above, the SiO ₂ film 108 that defines the current non-injection region is formed.
However, since the adhesiveness to the underlying p-type GaInP layer 106 is not good, there is a problem that a defect due to peeling of the SiO ₂ film 108 may occur.

On the other hand, the conventional AlGaI shown in FIG.
The n-type GaInP layer 2 is used for manufacturing the nP-based semiconductor laser.
02, n-type AlGaInP layer 203, undoped AlG
Epitaxial growth of aInP layer 204, p-type AlGaInP layer 205 and p-type GaInP layer 206 and n-type G
Since it is necessary to perform the epitaxial growth of the aAs layer 207 and the p-type GaAs layer 208 a total of three times, there is a problem in that manufacturing takes time. Further, since the p-type GaAs layer 208 has large unevenness on the underlying surface,
Since unevenness occurs on the surface of the layer 208, this p-type Ga
When the p-side electrode 209 is formed on the As layer 208 by a vacuum vapor deposition method or the like, a defect such as step breakage may occur.

Therefore, an object of the present invention is to provide p-type Ga.
When a p-side electrode is provided on a cap layer made of As and has an end face current non-injection structure, it can be easily manufactured regardless of whether it is a gain waveguide type or a refractive index waveguide type. It is an object of the present invention to provide a semiconductor laser and a method for manufacturing the semiconductor laser which can be formed without any problems such as peeling of the SiO ₂ film and step breakage of the p-side electrode.

[0010]

In order to achieve the above object, the first invention of the present invention is to provide an n-type cladding layer (3) laminated on a substrate (1) and an n-type cladding layer (3). ) A cap composed of an active layer (4) laminated on the p-type clad layer, a p-type clad layer (5) laminated on the active layer (4), and a p-type GaAs layer laminated on the p-type clad layer (5) Layer (7),
In a semiconductor laser having a p-side electrode (9) provided on the cap layer (7) and having an end face current non-injection structure, at least the surface layer of the cap layer (7) in the current injection region is a p-side electrode. (9) has a carrier concentration that makes ohmic contact, and the cap layer (7) in the current non-injection region has a carrier concentration that does not make ohmic contact with the p-side electrode (9).

In the first aspect of the present invention, typically, the carrier concentration of the cap layer in the current non-injection region is less than 1 × 10 ¹⁹ cm ⁻³ , and the carrier concentration of the cap layer in the current injection region is less than 1 × 10 ¹⁹ cm ^−3. 1 × 10 ¹⁹ cm ^-3 or more,
It is preferably 2 × 10 ¹⁹ cm ⁻³ or more.

A second aspect of the present invention is an n-type cladding layer (3) laminated on a substrate (1), an active layer (4) laminated on the n-type cladding layer (3), and an active layer. A p-type clad layer (5) laminated on the layer (4), a cap layer (7) made of p-type GaAs laminated on the p-type clad layer (5), and provided on the cap layer (7). In a method for manufacturing a semiconductor laser having an end face current non-injection structure having a p-side electrode (9) formed on the substrate (1), an n-type cladding layer (3), an active layer (4) and a p-type A step of sequentially growing the clad layer (5) and then growing a cap layer (7) on the p-type clad layer (5) so that the p-side electrode (9) has a carrier concentration such that the p-side electrode (9) does not make ohmic contact; At least the surface layer of the cap layer (7) in the portion to be the implantation region has p-type impurities. A step of setting the carrier concentration at which the p-side electrode (9) is in ohmic contact with the cap layer (7) in the portion to be the current injection region by selective doping, and the p-side electrode ( 9) is formed.

In one embodiment of the second aspect of the present invention, the cap layer is made to have a carrier concentration such that the p-side electrode does not make ohmic contact with the cap layer by a metal organic chemical vapor deposition method using trimethylgallium as a Ga raw material. Grow. Here, when triethylgallium is used as a Ga raw material, as an experimental fact, the incorporation of the p-type impurity from the dopant of the p-type impurity supplied together with the triethylgallium into the grown crystal is fast, and the concentration of the p-type impurity is high. Therefore, it is difficult to keep the carrier concentration low, whereas when trimethylgallium, which has a higher thermal decomposition temperature than triethylgallium, is used as the Ga raw material, p that is incorporated into the grown crystal from the p-type impurity dopant is used. It is easy to keep the concentration of the type impurities and hence the carrier concentration low.

In another embodiment of the second aspect of the present invention, the p-side electrode has a carrier concentration such that the p-side electrode does not make ohmic contact with the cap layer by metal organic chemical vapor deposition using triethylgallium as a Ga raw material. As described above, the flow rate of the dopant of the p-type impurity is limited to grow. In this case, by limiting the flow rate of the p-type impurity dopant, the carrier concentration of the grown crystal can be easily suppressed to a low level, even though triethylgallium is used as the Ga raw material.

In still another embodiment of the second aspect of the present invention, the carrier concentration is adjusted so that the p-side electrode does not make ohmic contact with the cap layer by metal organic chemical vapor deposition using triethylgallium as a Ga raw material. The growth temperature is controlled so as to maintain the growth. In this case, by controlling the growth temperature, specifically, by setting the growth temperature higher, it becomes difficult for p-type impurities to be taken into the grown crystal. Therefore, triethylgallium is used as the Ga raw material. Nevertheless, the carrier concentration of the grown crystal can be easily kept low.

In the second invention of the present invention, typically, the carrier concentration of the cap layer grown on the p-type cladding layer is less than 1 × 10 ¹⁹ cm ⁻³ , and the cap in the portion to be the current injection region is formed. The carrier concentration of the layer is 1 × 10
It is at least ¹⁹ cm ⁻³ , preferably at least 2 × 10 ¹⁹ cm ⁻³ .

In the present invention, the p-type impurity contained in the cap layer is, for example, Zn or Mg.

In the present invention, typically, the n-type cladding layer, the active layer and the p-type cladding layer are made of a III-V group compound semiconductor.

In the present invention, the p-side electrode is, for example,
It has a structure in which a Ti film, a Pt film, and an Au film are sequentially stacked.

[0020]

According to the semiconductor laser of the first aspect of the present invention, at least the surface layer of the cap layer in the current injection region has a carrier concentration with which the p-side electrode is in ohmic contact, and the cap layer in the current non-injection region. Since the p-side electrode has a carrier concentration that does not make ohmic contact, the current injected from the p-side electrode during operation is selectively passed through the cap layer in the current injection region where the p-side electrode is in ohmic contact. Flow, which realizes an end face current non-injection structure. In this case, since it is not necessary to form the SiO ₂ film to form the end face current non-injection structure, there is no problem of defects due to the peeling. Further, when the semiconductor laser is of the refractive index guided type, the cap layer is patterned in a stripe shape and the current blocking layers are provided on both sides thereof, and the surfaces of the cap layer and the current blocking layer are flat. By doing so, there is no possibility that a defect such as a step break will occur when the p-side electrode is formed on the cap layer by a vacuum deposition method or the like. When the semiconductor laser is a gain waveguide type, a cap layer is laminated on the entire surface in the same manner as the n-type clad layer, the active layer and the p-type clad layer, so that the p-layer is formed on the cap layer.
When forming the side electrode by a vacuum vapor deposition method or the like, there is no fear that a defect such as a step break will occur. Further, the number of times of epitaxial growth required for manufacturing this semiconductor laser is such that the epitaxial growth of the n-type clad layer, the active layer, the p-type clad layer and the cap layer and the number of epitaxial growth of the current blocking layer are performed even when the semiconductor laser is a refractive index guided type. It is only twice with epitaxial growth, and less than once with the conventional method. Therefore, it is easy to manufacture.

According to the method for manufacturing a semiconductor laser according to the second aspect of the present invention, the semiconductor laser according to the first aspect of the present invention can be easily manufactured.

[0022]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an AlGaInP-based semiconductor laser according to the first embodiment of the present invention. This AlGa
The InP-based semiconductor laser is a refractive index guided semiconductor laser having an end face current non-injection structure.

As shown in FIG. 1, in the AlGaInP semiconductor laser according to the first embodiment, n-type Ga is used.
On the As substrate 1, an n-type GaAs layer 2 as a buffer layer, an n-type AlGaInP layer 3 as an n-type cladding layer,
For example, an active layer 4 made of an undoped GaInP layer, a p-type AlGaInP layer 5 as a p-type cladding layer, a p-type GaInP layer 6 as a contact layer, and a p-type GaAs layer 7 as a cap layer are sequentially stacked. here,
Upper layer of p-type AlGaInP layer 5, p-type GaInP layer 6
The p-type GaAs layer 7 is patterned in a stripe shape. Here, p except for this stripe part
The thickness of the AlGaInP layer 5 is, for example, 0.2 to 0.3 μm.
m. Further, this striped p-type AlGaI
nP layer 5, p-type GaInP layer 6 and p-type GaAs layer 7
N-type GaAs as a current blocking layer on both sides of the
The layer 8 is embedded. The Al composition ratio of the n-type AlGaInP layer 3 and the p-type AlGaInP layer 5 is 0.7, for example.

P-type GaAs layer 7 and n-type GaAs layer 8
A p-side electrode 9 having a Ti / Pt / Au structure, for example, is provided on the above. In this case, the carrier concentration of both ends 7a and 7b of the striped p-type GaAs layer 7 in contact with the p-side electrode 9 in the cavity length direction is the p-side electrode 9
Is a value which does not make ohmic contact, that is, less than 1 × 10 ¹⁹ cm ⁻³ , and the carrier concentration of the central portion 7c sandwiched between these two end portions 7a and 7b causes the p-side electrode 9 to make ohmic contact. The value, that is, at least 1 × 10 ¹⁹ cm ⁻³ or more, preferably about 2 × 10 ¹⁹ cm ⁻³ or more. As a result, the p-side electrode 9 is p-type Ga
Only the central portion 7c of the As layer 7 is in ohmic contact, and the both end portions 7a and 7b are not in ohmic contact.

On the other hand, an n-side electrode 10 such as an In electrode is in ohmic contact with the back surface of the n-type GaAs substrate 1.

Next, a method of manufacturing the AlGaInP based semiconductor laser according to the first embodiment having the above-mentioned structure will be described.

As shown in FIG. 2, first, for example, 660 to 700 is formed on the n-type GaAs substrate 1 by MOCVD.
N-type GaAs layer 2, n-type AlGa at a growth temperature of about ℃
InP layer 3, active layer 4 composed of undoped GaInP layer, p-type AlGaInP layer 5 and p-type GaInP layer 6
Are sequentially epitaxially grown. In the epitaxial growth by the MOCVD method, triethylgallium (TE) which is an ethyl-based organometallic compound is used as a raw material of Ga, In and Al which are group III elements.
G), triethylindium (TEI) and triethylaluminum (TEA) are used, and the group V element As is used.
Arsine (AsH ₃ ) and phosphine (PH ₃ ) are used as the raw materials for P and P, respectively. Further, as a dopant of the n-type impurity, for example, hydrogen selenide (H ₂ S
e) and dimethylzinc (DMZ), for example, is used as the p-type impurity dopant.

Next, the Ga raw material is switched from TEG to trimethylgallium (TMG), and p-type GaIn is formed by the MOCVD method using this TMG and AsH ₃ as raw materials.
A p-type GaAs layer 7 is epitaxially grown on the P layer 6. At this time, Zn is doped so that the carrier concentration of the p-type GaAs layer 7 is less than 1 × 10 ¹⁹ cm ⁻³ . In this case, since TMG has a higher thermal decomposition temperature than TEG, the controllability of Zn doping is better than when TEG is used, and thus the p-type GaAs layer 7 is formed.
It is easy to set the carrier concentration of 1 to less than 1 × 10 ¹⁹ cm ⁻³ .

Next, after a SiO ₂ film 11 is formed on the entire surface of the p-type GaAs layer 7 by, for example, a vacuum evaporation method, this Si is formed.
The O ₂ film 11 is patterned into a stripe shape by etching.

Next, as shown in FIG. 3, using the SiO ₂ film 11 as a mask, for example, reactive ion etching (R
By the IE) method, the p-type AlGaInP layer 5 is etched in the direction perpendicular to the substrate surface to a depth in the middle in the thickness direction. At this time, p of the remaining portion after this etching
The thickness of the type AlGaInP layer 5 is set to 0.2 to 0.3 μm.

Next, as shown in FIG. 4, a SiO ₂ film 11 is formed.
By using MO as a growth mask, the p-type AlGaInP layer 5, the p-type GaInP layer 6 and the p-type GaAs layer 7 on both sides of the p-type AlGaInP layer 5 and the p-type AlGaInP layer 7 are formed by MOCVD.
An n-type GaAs layer 8 is selectively epitaxially grown on the InP layer 5 to fill this portion. At this time, p-type Ga
The surfaces of the As layer 7 and the n-type GaAs layer 8 are made flat.

Next, after removing the SiO ₂ film 11 by etching, as shown in FIG. 5, an opening 12a is formed on the p-type GaAs layer 7 and the n-type GaAs layer 8 at a portion corresponding to the current injection region. The diffusion mask 12 is formed. The diffusion mask 12 can be formed of, for example, a SiN _x film or an Al ₂ O ₃ film.

Next, for example, diethyl zinc (DEZ) is used as a p-type impurity dopant in an AsH ₃ gas atmosphere, and at a temperature of, for example, about 600 ° C., the diffusion mask 1
Zn is selectively diffused into the p-type GaAs layer 7 through the second opening 12a. This Zn diffusion is such that the carrier concentration of the p-type GaAs layer 7 in the Zn diffused portion is at least 1 × 10 ¹⁹ cm ⁻³ or more, preferably 2 × 10 ¹⁹ cm ^−3.
Try to be around or above.

Next, after removing the diffusion mask 12, FIG.
As shown in, a Ti film, a Pt film, and an Au film are sequentially formed on the p-type GaAs layer 7 and the n-type GaAs layer 8 by, for example, a vacuum deposition method to form a p-side electrode 9 having a Ti / Pt / Au structure. I, on the back surface of the n-type GaAs substrate 1.
An n-side electrode 10 made of n is formed.

Next, the n-type GaAs substrate 1 on which the laser structure is formed as described above is cleaved in a bar shape to form both resonator end faces, and after further end face coating,
The bar is cleaved into chips, and the desired semiconductor laser is completed as shown in FIG.

As described above, the index-guided AlGaInP having the end face current non-injection structure according to the first embodiment.
The number of times of epitaxial growth required for manufacturing the system-based semiconductor laser is two, and the number of times of epitaxial growth is one as compared with the conventional index-guided AlGaInP-based semiconductor laser having the end face current non-injection structure shown in FIG. Few times. Therefore, it is easy to manufacture. Further, since the underlying surface of the p-side electrode 9 is flat, there is no risk of step breakage when forming the p-side electrode 9.

Next, a second embodiment of the present invention will be described. In the second embodiment, the AlGaInP based semiconductor laser according to the first embodiment shown in FIG. 1 is manufactured by a method different from that of the first embodiment. That is, in the first embodiment, TEG and T, which are ethyl-based organometallic compounds, are used as raw materials for the group III elements Ga, In and Al.
The n-type GaAs layer 2, the n-type AlGaInP layer 3, the active layer 4, the p-type AlGaInP layer 5, and the p-type GaInP layer 6 are formed by the MOCVD method using EI and TEA, respectively.
MOC using TMG, which is a methyl-based organometallic compound, as a Ga raw material after sequentially epitaxially growing
Although the p-type GaAs layer 7 is epitaxially grown by the VD method, in the second embodiment, p-type GaAs is used.
The layer 7 is also epitaxially grown by the MOCVD method using TEG, which is an ethyl-based organometallic compound, as a Ga raw material. However, at this time, by limiting the flow rate of DMZ as the dopant of the p-type impurity during the epitaxial growth of the p-type GaAs layer 7, the p-type GaA
The carrier concentration of the s layer 7 is set to be less than 1 × 10 ¹⁹ cm ⁻³ . Since the second embodiment is the same as the first embodiment except for the above, the description thereof will be omitted. Also in the second embodiment, the same advantages as those in the first embodiment can be obtained.

Next, a third embodiment of the present invention will be described. In the third embodiment, the AlGaInP-based semiconductor laser according to the first embodiment shown in FIG. 1 is manufactured by a method different from those of the first and second embodiments. That is, in this third embodiment, instead of limiting the flow rate of DMZ as in the second embodiment, the growth temperature during the epitaxial growth of the p-type GaAs layer 7 is set to n-type GaAs.
Layer 2, n-type AlGaInP layer 3, active layer 4, p-type AlG
It is higher than the growth temperature at the time of epitaxial growth of the aInP layer 5 and the p-type GaInP layer 6, and the carrier concentration of the p-type GaAs layer 7 is set to be less than 1 × 10 ¹⁹ cm ⁻³ by setting the temperature to 700 ° C. or higher. To do. This third
The other points of the embodiment are the same as those of the first embodiment, and the description thereof will be omitted. Also according to this third embodiment, the first
The same advantages as the embodiment can be obtained.

The embodiments of the present invention have been specifically described above, but the present invention is not limited to the above-mentioned embodiments, and various modifications can be made based on the technical idea of the present invention.

For example, in the above-mentioned first embodiment, second embodiment and third embodiment, the case where the present invention is applied to a refractive index guided AlGaInP based semiconductor laser having an end face current non-injection structure will be described. However, the present invention is directed to a gain waveguide type AlGa having an end face current non-injection structure.
It goes without saying that it can also be applied to an InP semiconductor laser. In this case, for example, as shown in FIG. 1, the upper layer portion of the p-type AlGaInP layer 5, the p-type GaInP layer, and the like.
The p-side electrode 9 is formed on the p-type GaAs layer 7 without patterning the layer 6 and the p-type GaAs layer 7 in stripes. At this time, the central portion 7 of the p-type GaAs layer 7
The carrier concentration of the portion other than c is set to a carrier concentration at which the p-side electrode 9 does not make ohmic contact, that is, less than 1 × 10 ¹⁹ cm ⁻³ .

The present invention may be applied to a semiconductor laser other than the AlGaInP type semiconductor laser as long as the p-type GaAs layer is used as the cap layer.
For example, it may be applied to an AlGaAs semiconductor laser.

[0042]

As described above, according to the present invention, both the gain waveguide type and the refractive index waveguide type can be easily manufactured, and the SiO ₂ film peels off. It is possible to realize a semiconductor laser having an end face current non-injection structure, which does not cause a problem of defects such as breakage of the p-side electrode or a step.

[Brief description of drawings]

FIG. 1 is a perspective view showing an AlGaInP-based semiconductor laser according to a first embodiment of the present invention.

FIG. 2 is a perspective view for explaining a method of manufacturing an AlGaInP-based semiconductor laser according to the first embodiment of the present invention.

FIG. 3 is a perspective view for explaining a method of manufacturing an AlGaInP-based semiconductor laser according to the first embodiment of the present invention.

FIG. 4 is a perspective view for explaining a method of manufacturing an AlGaInP-based semiconductor laser according to the first embodiment of the present invention.

FIG. 5 is a perspective view for explaining the method of manufacturing the AlGaInP-based semiconductor laser according to the first embodiment of the present invention.

FIG. 6 is a perspective view for explaining a method of manufacturing an AlGaInP-based semiconductor laser according to the first embodiment of the present invention.

FIG. 7 is a perspective view showing a conventional gain-guiding type AlGaInP-based semiconductor laser having a facet current non-injection structure.

FIG. 8 is a perspective view showing a conventional index-guided AlGaInP-based semiconductor laser having a non-facet current injection structure.

[Explanation of symbols]

1 n-type GaAs substrate 3 n-type AlGaInP layer 4 active layer 5 p-type AlGaInP layer 6 p-type GaInP layer 7 p-type GaAs layer 8 n-type GaAs layer 9 p-side electrode 10 n-side electrode 11 SiO ₂ film 12 diffusion mask

Claims (17)

[Claims] 1. An n-type cladding layer laminated on a substrate, an active layer laminated on the n-type cladding layer, a p-type cladding layer laminated on the active layer, and a p-type cladding layer. In a semiconductor laser having a cap layer made of p-type GaAs laminated on top and a p-side electrode provided on the cap layer, and having an end face current non-injection structure, the cap layer in the current injection region is At least the surface layer has a carrier concentration with which the p-side electrode makes ohmic contact, and the cap layer in the current non-injection region has a carrier concentration at which the p-side electrode does not make ohmic contact. 2. The semiconductor laser according to claim 1, wherein a carrier concentration of the cap layer in the current non-injection region is less than 1 × 10 ¹⁹ cm ⁻³ . 3. The semiconductor laser according to claim 1, wherein the carrier concentration of the cap layer in the current injection region is 1 × 10 ¹⁹ cm ⁻³ or more. 4. The semiconductor laser according to claim 1, wherein the carrier concentration of the cap layer in the current injection region is 2 × 10 ¹⁹ cm ⁻³ or more. 5. The semiconductor laser according to claim 1, wherein the p-type impurity contained in the cap layer is Zn or Mg. 6. The semiconductor laser according to claim 1, wherein the n-type clad layer, the active layer and the p-type clad layer are made of a III-V group compound semiconductor. 7. The semiconductor laser according to claim 1, wherein the p-side electrode has a structure in which a Ti film, a Pt film, and an Au film are sequentially stacked. 8. An n-type cladding layer laminated on a substrate, an active layer laminated on the n-type cladding layer, a p-type cladding layer laminated on the active layer, and a p-type cladding layer. A method for manufacturing a semiconductor laser having a cap layer made of p-type GaAs, which is stacked on the cap layer, and a p-side electrode provided on the cap layer, and having an end face current non-injection structure. a step of sequentially growing an n-type clad layer, the active layer, and the p-type clad layer, and then growing the cap layer on the p-type clad layer so that the p-side electrode has a carrier concentration that does not make ohmic contact. And by selectively doping at least the surface layer of the cap layer in the portion to be the current injection region with a p-type impurity, the cap in the portion to be the current injection region. The semiconductor laser manufacturing method characterized in that it comprises a step of setting the layer to the carrier concentration of the p-side electrode is ohmic contact, and forming the p-side electrode to the cap layer. 9. The cap layer is grown by a metalorganic chemical vapor deposition method using trimethylgallium as a Ga raw material so that the p-side electrode has a carrier concentration that does not make ohmic contact. Claim 8
A method for manufacturing the semiconductor laser described. 10. The flow rate of a p-type impurity dopant is controlled by a metal organic chemical vapor deposition method using triethylgallium as a Ga source so that the cap layer has a carrier concentration such that the p-side electrode does not make ohmic contact. 9. The method of manufacturing a semiconductor laser according to claim 8, wherein the semiconductor laser is grown. 11. The cap layer is grown by a metalorganic chemical vapor deposition method using triethylgallium as a Ga raw material while controlling the growth temperature so that the p-side electrode has a carrier concentration that does not make ohmic contact. The method for manufacturing a semiconductor laser according to claim 8, wherein 12. The method of manufacturing a semiconductor laser according to claim 8, wherein the carrier concentration of the cap layer grown on the p-type cladding layer is less than 1 × 10 ¹⁹ cm ⁻³ . 13. The method of manufacturing a semiconductor laser according to claim 8, wherein a carrier concentration of the cap layer in a portion to be the current injection region is 1 × 10 ¹⁹ cm ⁻³ or more. 14. The method of manufacturing a semiconductor laser according to claim 8, wherein a carrier concentration of the cap layer in a portion which becomes the current injection region is 2 × 10 ¹⁹ cm ⁻³ or more. 15. The method of manufacturing a semiconductor laser according to claim 8, wherein the p-type impurity contained in the cap layer is Zn or Mg. 16. The method of manufacturing a semiconductor laser according to claim 8, wherein the n-type clad layer, the active layer and the p-type clad layer are made of a III-V group compound semiconductor. 17. The p-side electrode comprises a Ti film, a Pt film and Au.
9. The method for manufacturing a semiconductor laser according to claim 8, which has a structure in which a film and a film are sequentially laminated.