JPH03159289A - Manufacture of semiconductor laser - Google Patents

Abstract

PURPOSE:To realize a semiconductor laser manufacturing method through which a lateral mode control structure can be formed in an easy process by a method wherein an active layer is put into a natural superlattice state, the natural superlattice state of the active layer is selectively damaged to turn the active layer partially into a disordered state, and thus the active layer partially left in the natural superlattice state in a stripe is formed. CONSTITUTION:A stripe-shaped region, which is composed of a clad layer 12, an active layer 14, a clad layer 16, and a buffer layer 18 and located at the center of them, is in a natural superlattice state that atoms are regularly arranged, and a peripheral region hatched with slant lines are turned from a natural superlattice state into a disordered state by damage. A natural superlattice region is smaller than a region of mixed crystal state in band gap and larger in refractive index, therefore the natural superlattice region of the active layer 14 located at its center is larger than its peripheral disordered region in refractive index, so that it serves as a lateral mode controlled active region 14a. By this method, the active layer 14a can be formed only by making the active layer, which has been formed in a natural superlattice state, disordered. By this setup, a lateral mode controlled semiconductor laser can be very easily manufactured.

Description

[Detailed Description of the Invention] [Summary] For example, GaInP/Aj! Regarding a method for manufacturing a double heterojunction semiconductor laser such as a GaInP-based semiconductor laser, the purpose of this invention is to provide a method for manufacturing a semiconductor laser that can form a transverse mode control structure through simple steps. forming an active layer by one-time vapor phase growth on a compound semiconductor substrate having a crystal surface in which different elements are exposed at the same time, and bringing the active layer into a natural superlattice state; The lattice state is selectively destroyed and disordered to form an active layer in which a striped natural superlattice state remains.

[Industrial Application Field] The present invention is applicable to, for example, Ga I nP/AJ! The present invention relates to a method for manufacturing a double heterojunction semiconductor laser such as a GaI nP type semiconductor laser.

GaInP/AlG that emits laser light in the 0.6 μm band
AlnP semiconductor lasers are used in laser disks and laser printers capable of high-density storage, and are expected to be applied to optical communications using plastic fibers.

[Prior Art] In a conventional AJGaInP semiconductor laser, a ridge-type structure is employed to control a transverse mode in a direction perpendicular to the optical axis of laser light.

FIG. 15 shows a conventional semiconductor laser having a ridge type structure.

An n-AJGaInP cladding layer 104 is formed on an n-GaAs substrate 100 via an n-GaAs buffer layer 102.
is formed. A GaInP active layer 106 is formed on the cladding layer 104, and a p-A layer is formed on this active layer 106.
A cladding layer 108 of lGaInP is formed. On this CLA layer 108, a stripe-shaped p-Aj
A GaAs cladding layer 110 is formed to perform transverse mode control. A contact layer 112.5ix of p-GaAs is formed on the cladding layer 110 of p-AjGaAs.
T i / P t / A u via the N4 layer 113
An electrode layer 114 is formed. n-GaAs substrate 1
On the bottom surface of 00 is an electrode layer 11 of A u G e / A u
6 is formed.

In this ridge-type semiconductor laser, the transverse mode of the laser beam is controlled by increasing the refractive index of the central stripe-shaped region of the active layer 106.

The semiconductor laser shown in FIG. 16 is a regrowth type semiconductor laser in which a ridge type structure is buried with GaAs.

An n-GaAs buffer layer 12 is formed on a GaAs substrate 120.
2 through n (Ajo, aGao, t) aIno,
sP first cladding layer 124, n-(Aj o, b G
ao, a) o, s I no, s P's second club.
A Rad layer 126 is formed. Second cladding layer 126
On top (AJ o, +sG ao, ms) o, s
An active layer 128 of I no, s P is formed on this active layer 128, and P(AJ o, a Gao, < ) o
, s I no, s P are formed. On the second cladding layer 130, (Ajo,
+5 Gao, ss) a, s I n. ,, P in a stripe shape through the etching stopper layer 132 of P.
(Ajo, s Gao, *) o, 5Ino, sP
A first cladding layer 134 is formed. This first cladding layer 134 is buried by a buried layer 136 of n-GaAs. First cladding layer 134 and buried layer 13
6, a p-caAs contact layer 138.140
The Ti/Pt/Au electrode layer 142 is
is formed, and AuGeNi is formed on the lower surface of the GaAs substrate 120.
An electrode layer 144 is formed.

In this regrown semiconductor laser, the transverse mode of the laser beam is controlled by increasing the absorption of the laser beam in the peripheral region of the active layer 128.

[Problems to be Solved by the Invention] However, in ridge type semiconductor lasers, the top surface on which the ridge type structure is formed is uneven, and the semiconductor laser is bonded upside down, which causes distortion and lacks reliability. There was a problem.

Furthermore, in the regrowth type semiconductor laser, the semiconductor layer is grown twice, which makes the manufacturing process complicated.

An object of the present invention is to provide a method for manufacturing a semiconductor laser that can form a transverse mode control structure through simple steps.

[Means for solving the problem] For example, GaInP or AlGa on a GaAs substrate.
It is known that when crystal-growing InP by the MOCVD method, a natural superlattice in which group (2) atoms are regularly arranged is formed by using a (100)-plane substrate and controlling growth conditions such as temperature. Regarding this phenomenon, see Akiko Gomei, Kou Suzuki, and Sumio Iijima: "Band gap energy anomaly and natural superlattice of rGalnP", Applied Physics, Vol. 58, No. 9.
No. (1989) pp. 1360-1367.

The present invention is based on the knowledge that when impurities are added to this natural superlattice state, it becomes disordered. The natural superlattice state is disordered and has a smaller bandgap and higher refractive index than the mixed crystal state, so the semiconductor layer formed to be in the natural superlattice state is partially disordered to increase the bandgap and refractive index. Transverse mode control of the semiconductor laser can be performed by partially changing the value.

Therefore, an object of the present invention is to form an active layer by one-time vapor phase growth on a compound semiconductor substrate having a crystal surface in which elements having substantially different atomic radii are simultaneously exposed;
a step of bringing the active layer into a natural superlattice state, and selectively destroying the natural superlattice state of the active layer to make it disordered to form an active layer in which a striped natural superlattice state remains. This is achieved by a semiconductor laser manufacturing method characterized by including the steps of:

[Operation] According to the present invention, by bringing the active layer into a natural superlattice state and selectively disordering it, a semiconductor laser with transverse mode control can be manufactured very easily.

[Example] A semiconductor laser according to a first example of the present invention will be described with reference to FIG.

On the n-GaAs substrate 10, a 1 μm thick n(Ajo,s
A cladding layer 12 of Gao, t ) o, s I no, s P is formed, and a 0.1 μm thick layer is formed on the cladding layer 12.
A thick active layer 14 of Ga I nP is formed. On the active layer 14, 1 μm thick P (AJo, 7Gao,
i) A cladding layer 16 of o, sIno, and sP is formed. A layer with a thickness of 0.5 μm is formed on the cladding layer 16 via a buffer layer 18 of p-GaInP with a thickness of 0.1 μm.
A μm thick p-GaAs contact layer 20 is formed,
Au/Zn/Au on this contact layer 2o
An electrode layer 22 is formed on the lower surface of the n-GaAs substrate 10, and a t@ layer 24 of AuGe/Au is formed on the lower surface of the n-GaAs substrate 10.

In this embodiment, the stripe-shaped region in the middle of the cladding layer 12, active layer 14, cladding layer 16, and buffer layer 18 is in a natural superlattice state in which atoms are regularly arranged, and the surrounding region hatched with diagonal lines The natural superlattice state is destroyed and becomes disordered. As mentioned above, the natural superlattice region has a smaller band gap and a higher refractive index than the mixed crystal state. Therefore, the natural superlattice state region in the center of the active layer 14 has a larger refractive index than the surrounding disordered region. The active region 14a is controlled in transverse mode.

In this way, according to this embodiment, the active region can be formed simply by disordering the active layer formed to have a natural superlattice state, so it is possible to manufacture a semiconductor laser with transverse mode control extremely easily. .

In addition, in the above embodiment, the cladding layer 12, the active layer 14,
Cladding layer 16, buffer layer 18 and contact layer 20
Although all of the layers were in a natural superlattice state, the layers other than the active layer 14 may be in a mixed crystal state.

Next, a method for manufacturing a semiconductor laser according to a second embodiment of the present invention will be described with reference to FIG.

First, a (100) plane n-GaAs substrate 10 (or (Z
oo) A GaAs substrate tilted up to 15 degrees from the plane may also be used)
On top, 1 μm was grown at a growth temperature of about 650°C by MOCVD method.
m thickness n (Ajo, 1Gaa7) o, s I n
o,s P cladding layer 12.0°1, um thick GaI
nP active layer 14.1 μm thick p-(AjO,7Ga
(1, s ) o, s I no, i P cladding layer 16.0.1. czm thick p-GaInP buffer layer 18.0.5 μm thick p-GaAs contact layer 20
grow sequentially.

As the growth gas, phosphine gas is used as a phosphorus source, trimethylindium as an indium source, triethylgallium as a gallium source, and trimethylaluminum as an aluminum source.

The GaAs substrate is <100) and the growth temperature is approximately 650°C.
By doing so, each grown layer becomes in a natural superlattice state (FIG. 2(a)).

Next, a mask layer 26 of SiO2 having a stripe shape with a width of 4 μm is formed at the center of the contact layer 20. Subsequently, Zn, which is an impurity, is diffused from the surface at about 600° C. using Z n As 2 . Then, mask layer 2
6, Zn diffuses into the interior from the unmasked surface, and the natural superlattice state in the hatched region is destroyed and disordered. The peripheral region of the active layer 14 is also disordered, and the active region 14a with a high refractive index is located in the center.
is formed (Fig. 2(b)).

Next, the mask layer 26 is removed and the A layer is placed on the contact layer 20.
U/Zn/Au electrodes 7122 are formed, and AuGe is formed on the lower surface of the n-GaAs substrate 10.
/Au electrode layer 24 is formed to complete the semiconductor laser (FIG. 2(C)).

As described above, according to the manufacturing method of this embodiment, the transverse mode can be easily controlled by simply diffusing Zn from the surface.

Next, a method for manufacturing a semiconductor laser according to a third embodiment of the present invention will be described with reference to FIG. Components that are the same as those in FIG. 2 are given the same reference numerals and their explanations will be omitted.

This embodiment is characterized in that activation annealing is performed after impurity ion implantation.

First, a cladding layer 12, an active layer 14, a cladding layer 16, a buffer layer 18, and a contact layer 20 in a natural superlattice state are sequentially grown on an n-GaAs substrate 10 as shown in FIG. 3(a).
) After that, Zn ions are implanted around the central stripe-shaped region. After that, when activation annealing treatment is performed to activate the ion-implanted Zn by heating, the natural superlattice state of the ion-implanted region hatched with diagonal lines is destroyed and disordered (Fig. 3(b)). Thereafter, the electrode layer 22 and the electrode layer 24 are formed to complete the semiconductor laser (third
Figure (C)).

As described above, in this embodiment, disorder is created by implanting impurity ions, so that the disordered region can be formed into a vertical shape with little lateral spread. Therefore, the active region of the active layer can be formed to have a desired width.

Next, a method for manufacturing a semiconductor laser according to a fourth embodiment of the present invention will be described with reference to FIG. Components that are the same as those in FIG. 2 are given the same reference numerals and their explanations will be omitted.

This embodiment is characterized in that impurities are diffused from a high concentration impurity layer.

First, the cladding layer 12, the active layer 14, the cladding layer 16, and the buffer layer 18 in a superlattice state are sequentially grown on an n-GaAs substrate. Subsequently, on the buffer layer 18,
0.5 μm thick p with stripe-shaped area
”-G a As high concentration impurity layer 28 is formed,
A contact layer 20 of p-GaAs having a thickness of 1 μm is formed on the buffer layer 18 and the high concentration impurity layer 28 (FIG. 4(a)).

Next, when heated, the impurity diffuses through the high concentration impurity layer 28, and the natural superlattice state in the hatched region is destroyed and disordered (FIG. 4(b)).

Next, an electrode layer 22 and an electrode layer 24 are formed to complete the semiconductor laser (FIG. 4(C)).

As described above, according to the manufacturing method of this embodiment, the natural superlattice state can be destroyed and disordered by impurity diffusion from the high concentration impurity layer.

(a)).

Next, a stripe-shaped mask layer 26 is formed in the center of the contact layer 20, and about 60
Zn, which is an impurity, is diffused from the surface at ℃. Then, Zn diffuses inside from the surface not masked by the mask layer 26, but unlike the case in FIG. 2, it becomes a vertical shape with less spread as shown by diagonal lines. This is because the composition of Aj of the second cladding layer 30 changes from 0.7 to 0.4, which makes it easier to diffuse as the distance from the surface increases. This is indicated by a broken line (Fig. 5(b)).

Next, the mask layer 26 is removed, and the electrode layer 22 and the electrode layer 2 are removed.
4 to complete the semiconductor laser (Fig. 5(C))
.

As described above, according to the manufacturing method of this example, the diffusion shape is controlled by changing the composition of the second cladding layer, and
The active region width can be controlled narrowly. Next, a method for manufacturing a semiconductor laser according to a fifth embodiment of the present invention will be described.
This will be explained using figures.

Components that are the same as those in FIG. 2 are given the same reference numerals and their explanations will be omitted.

This embodiment is characterized in that the diffusion shape is controlled by changing the composition of the cladding layer.

First, n-(AjO,7G
ao, s) I nP cladding layer 12, 'GaIn
Active layer 14 of P, p (AnO,7Gao,i)
A cladding layer 16 of InP is sequentially formed. p-AJlxGal-xA whose composition changes on this cladding layer 16
A second cladding layer 30 of s (x=0.4 to 0.7) is formed, and a pGaAs contact layer 20 is formed on the second cladding layer 30 (FIG. 5(a)).

Next, a stripe-shaped mask layer 26 is formed in the center of the contact layer 20, and Zn, which is an impurity, is diffused from the surface at about 600° C. using ZnA S 2 as a diffusion source. Then, Zn is removed from the surface not masked by the mask layer 26.
is diffused inside, but unlike the case in FIG. 2, it becomes a vertical shape with less spread as shown by diagonal lines. This is because the composition of Aj of the second cladding layer 30 changes from 0.7 to 0.4, which makes it easier to diffuse as the distance from the surface increases. This is indicated by a broken line (Fig. 5(b)).

Next, the mask layer 26 is removed, and the electrode layer 22 and the electrode layer 2 are removed.
4 to complete the semiconductor laser (Fig. 5(C))
.

As described above, according to the manufacturing method of this example, the diffusion shape is controlled by changing the composition of the second cladding layer, and
The active region width can be controlled narrowly.

Next, a method for manufacturing a semiconductor laser according to a sixth embodiment of the present invention will be described with reference to FIG. Components that are the same as those in FIG. 2 are given the same reference numerals and their explanations will be omitted.

This embodiment is characterized in that the element portion is processed into a mesa shape so that impurities are diffused from the side surface of the element having a mesa structure.

First, on the n-GaAs substrate 10, a natural superlattice state of n
(AJ O,7Gao,s) InP cladding layer 12, GaInP active layer 14, p-(Ana,
yGa66. ) InP cladding layer 16, p-caIn
P buffer layer 18, p-GaAs contact layer 20
are grown sequentially (Fig. 6(a)).

Next, a mask layer 3 of SiO2 is formed on the contact layer 20.
2 is formed, and using this mask layer 32 as a mask, the side surface of the element is etched to form a mesa shape, and from the side surface of this mesa shape, Z
Diffuse n. Then, Zn is diffused from the lateral direction,
The natural superlattice state in the hatched region is destroyed and disordered (FIG. 6(b)).

Thereafter, an electrode layer 22 and an electrode layer 24 are formed to complete the semiconductor laser (FIG. 6(C)).

As described above, in this embodiment, after forming into a mesa shape, the inert substance is diffused to make the structure disordered, so that the active region of the active layer can be formed to have a desired width.

Next, a method for manufacturing a semiconductor laser according to a seventh embodiment of the present invention will be described with reference to FIG. Components that are the same as those in FIG. 2 are given the same reference numerals and their explanations will be omitted.

This embodiment is characterized in that the natural superlattice state is attempted to be destroyed by locally heating.

First, on the n-GaAs substrate 10, a natural superlattice state of n
(Aja,s Gaa,s) InP cladding layer 12, GaInP active layer 14, p-(Ajo,s
Gao) I nP cladding layer 16, p-GaIn
Sequential growth of P buffer layer 18 (FIG. 6(a))
After forming an n-GaAs impurity layer 21 with striped regions on the buffer layer 18, a p-GaAs contact layer 20 is formed on the entire surface to form a current confinement structure (seventh step). Figure (a)).

Next, the natural superlattice state is destroyed by heating by locally irradiating with a laser beam or an electron beam. In the hatched region, the natural superlattice state is destroyed and disordered (FIG. 7(b)).

Next, an electrode layer 22 and an electrode layer 24 are formed to complete the semiconductor laser (FIG. 7(C)).

As described above, according to this embodiment, the natural superlattice state can be destroyed and disordered simply by locally irradiating the laser beam or electron beam from the outside.

In the seventh embodiment, the contact layer was locally heated after being formed, but the natural superlattice state may be destroyed and disordered by locally heating during the formation of the cladding layer.

Next, a method for manufacturing a semiconductor laser according to an eighth embodiment of the present invention will be described with reference to FIG.

In this embodiment, the p-type layer and the n-type layer are formed upside down.

First, p-GaInP is grown on a p-GaAs substrate 40 by MOCVD at a growth temperature at which a natural superlattice state is formed.
buffer layer 41, p (Ajo.

? Gao, i) I nP cladding layer 42, GaI
nP active layer 43, n − (Aja, 7Gao, i)
A cladding layer 44 of InP and a contact layer 45 of n-GaAs are sequentially grown (FIG. 8(a)).

Next, a mask layer 46 of S i 02 having a stripe shape with a width of 4 μm is formed at the center of the contact layer 45 . Subsequently, Zn, which is an impurity, is diffused from the surface at about 600° C. using ZnAs2 as a diffusion source.

Then, Zn diffuses inside from the surface not masked by the mask layer 46, and the natural superlattice state in the hatched area is destroyed and disordered. active layer 4
3, the peripheral region is also disordered, and an active region 43a with a low refractive index is formed in the center (FIG. 8(b)).

Next, the contact layer 45 is formed by etching into a stripe shape. Subsequently, a SiO2 layer 47 is formed, an opening is made in the SiO2 layer 47 on the contact layer 45, and an electrode layer 48 of AuGe/Au is formed on the entire surface. Further, an electrode layer 49 of Au/Zn/Au is also formed on the lower surface of the p-GaAs substrate 40 (FIG. 8(C)).

As described above, according to the manufacturing method of this embodiment, even for a semiconductor laser in which the p-type layer and the n-type layer are upside down, the Z
Transverse mode control can be easily performed by simply diffusing n.

A semiconductor laser according to a ninth embodiment of the present invention will be explained using FIG. 9.

On the p-GaAs substrate 50, O, 1 μm thick p-GaI
1 μm thick p (Aj
o, s Gao, s ) InP Cla-Rad layer 5
4 is formed, and a 0.1 μm thick G layer is formed on the cladding layer 54.
An active layer 56 of aInP is formed.

On the active layer 56 is a lum-thick n (Ajo, sGa.

, ) A cladding layer 58 of InP is formed.

A contact layer 62 of n-GaAs with a thickness of 1 μm is formed on the cladding layer 58 via a buffer layer 60 of n-GaAs with a thickness of 500 nm.
An electrode layer 64 of uGe/Au is formed, and p-
An A u /Zn/Au electrode layer 66 is formed on the lower surface of the GaAs substrate 50 .

In this embodiment, at least the stripe-shaped region in the center of the cladding layer 58 is in a natural superlattice state, and the surrounding area above the cladding layer 58, which is hatched with diagonal lines, is disordered due to the destruction of the natural superlattice state. has been done. As mentioned above, the natural superlattice region has a smaller band gap and a higher refractive index than the mixed crystal state, so the cladding layer 5
The region in the natural superlattice state at the center of the active region 5 has lower absorption loss and refractive index than the surrounding disordered region, and the active layer 56 below the region in the natural superlattice state is the active region 5 in which the transverse mode is controlled.
It becomes 6a.

In this way, according to this embodiment, the active region can be formed simply by disordering the cladding layer formed to have a natural superlattice state, so it is possible to manufacture a semiconductor laser with transverse mode control extremely easily. .

Note that in the above embodiment, the buffer layer 52 and the cladding layer 5
4. Although the active layer 56, cladding layer 58, and buffer layer 60 were all in a natural superlattice state, the layers other than the cladding layer 58 may be in a mixed crystal state.

Next, a method for manufacturing a semiconductor laser according to a tenth embodiment of the present invention will be described with reference to FIG.

if, p -G a As group 11i 50 above, M
0.1μm at a growth temperature of about 650'C by OCVD method
Thick p-GaInP buffer layer 52.1 μm thick (7)
P(Ajo, s Gaa, s ) InP cladding layer 54.0° 1 μm thick GaInP active layer 56.1 μm
A cladding layer of n(Ajo,sGao,s)InP with a thickness of 58.500 and a buffer layer of n-GaAs with a thickness of 0n-GaAs are sequentially grown. Since the growth temperature is approximately 650'C, each layer grown is in a natural superlattice state (Fig. 10 (
a)).

Next, a 5in2 mask layer 68 having a stripe shape with a width of 4 μm is formed at the center of the buffer layer 6o. continue,
Zn, which is an impurity, is diffused from the surface at about 6°0° C. using ZnA S 2 as a diffusion source. Then, the mask layer 68
Zn from the surface not masked by the buffer layer 6
o and diffuses into the cladding layer 58, and the natural superlattice state in the hatched area is destroyed and disordered (FIG. 10(b)). As a result, the natural superlattice state in the center of the cladding layer 58 is The absorption loss and refractive index of the state region are lower than the surrounding disordered region, and the active layer 56 under the region of the natural superlattice state is an active region 5 in which the transverse mode is controlled.
It becomes 6a.

Next, the mask layer 68 is removed, and a 1 μm thick n-GaAs contact layer 62 is grown again by MOCVD (FIG. 10C).

Next, A u G e /A is formed on the contact layer 60.
Then, an electrode layer 64 of Au/Zn/Au is formed on the lower surface of the n-GaAs substrate 5o to complete the semiconductor laser (FIG. 10(d)).

As described above, according to the manufacturing method of this embodiment, the transverse mode of the active layer can be easily controlled simply by diffusing Zn from the surface.

Next, a method for manufacturing a semiconductor laser according to an eleventh embodiment of the present invention will be described with reference to FIG. Components that are the same as those in FIG. 10 are given the same reference numerals and their explanations will be omitted.

This embodiment is characterized in that the impurity is introduced by performing activation annealing after ion-implanting the impurity.

First, a buffer layer 52, a cladding layer 54, an active layer 56, a cladding layer 58, and a buffer layer 6o in a natural superlattice state were sequentially grown on a P GaAs substrate 5o (see FIG. 11(a).
)) After that, Zn ions are implanted around the central stripe-shaped region. After that, when activation annealing treatment is performed to activate the ion-implanted Zn by heating, the natural superlattice state of the ion-implanted region hatched with diagonal lines is destroyed and disordered (Fig. 11(b)). Thereafter, a contact layer 62 is grown (FIG. 11(C)), and a pole layer 64 and an electrode layer 66 are formed to complete the semiconductor laser (the first
Figure 1 (d)).

As described above, in this embodiment, disorder is created by implanting impurity ions, so that the disordered region can be formed into a vertical shape with little lateral spread. Therefore, the active region of the active layer can be formed to have a desired width.

Next, a method for manufacturing a semiconductor laser according to a twelfth embodiment of the present invention will be described with reference to FIG. Components that are the same as those in FIG. 10 are given the same reference numerals and their explanations will be omitted.

This embodiment is characterized in that impurities are diffused from a high concentration impurity layer.

First, a buffer layer 52, a cladding layer 54, an active layer 56, a cladding layer 58, and a buffer layer 60 in a natural superlattice state are sequentially grown on a p-GaAs substrate 50. Next, on the buffer layer 60, a p+1-GaAs high concentration impurity layer 70 is formed with a stripe-shaped region having a thickness of 0.5 μm.
A 1 μm thick n-GaAs contact layer 62 is formed on the buffer layer 60 and the high concentration impurity layer 70 (FIG. 12(a)).

Next, when heated, impurities from the high concentration impurity 7170 are diffused, and the natural superlattice state in the hatched region is destroyed and disordered (FIG. 12(b)).

Next, 'f! jhf! A layer 64 and an electrode layer 66 are formed to complete the semiconductor laser (FIG. 12(C)).

As described above, according to the manufacturing method of this embodiment, the natural superlattice state can be destroyed by impurity diffusion from the high concentration impurity layer to create disorder.

Next, a method for manufacturing a semiconductor laser according to a thirteenth embodiment of the present invention will be described with reference to FIG. Components that are the same as those in FIG. 1O are given the same reference numerals and their explanations will be omitted.

In this embodiment, the diffusion shape is controlled by changing the composition of the cladding layer.

First, a buffer layer 52, a cladding layer 54, and an active layer 56 in a natural superlattice state are sequentially formed on a p-GaAs substrate 5o. n-Aj xG whose composition changes on this active layer 16
A cladding layer 58 of al-x I nP (x=0.4 to 0.7) is formed, and n-Ga is formed on the cladding layer 58.
Form a contact layer 62 of As (FIG. 13(a))
.

Next, a stripe-shaped mask layer 68 is formed in the center of the contact layer 60, and about 600 nm is formed using ZnAs2 as a diffusion source.
Zn, which is an impurity, is diffused from the surface at a temperature of .degree. Then, Zn diffuses into the interior from the surface not masked by the mask layer 68, but unlike the case in FIG. 10, it becomes a vertical shape with less spread as shown by diagonal lines. this is,
This is because the composition of Aj of the cladding layer 58 changes from 0.4 to 0.7, so that the farther from the surface it is, the easier it is to diffuse.0 The diffusion shape when there is no composition change is shown by a broken line for reference. (Figure 13(b)).

Next, the mask layer 68 is removed, and the electrode layer 64 and the electrode 16 are removed.
6 to complete the semiconductor laser (Fig. 13(C)
).

As described above, according to the manufacturing method of this embodiment, by changing the composition of the cladding layer, the diffusion shape can be controlled and the active region width can be controlled to be narrow.

Next, a method for manufacturing a semiconductor laser according to a fourteenth embodiment of the present invention will be described with reference to FIG. Components that are the same as those in FIG. 10 are given the same reference numerals and their explanations will be omitted.

In this embodiment, the element portion is processed into a mesa shape so that impurities are diffused from the side surfaces of the mesa structure.

First, a buffer layer 52, a cladding layer 54, and an active layer 56 in a natural superlattice state are sequentially grown on a p-GaAs substrate 50. Furthermore, a thick n layer with a natural superlattice state is formed on the active layer 56.
-(Ajo, s Gao, s ) A cladding layer 58 of InP and a thin p-GaAs contact layer 60 for contact are grown in sequence (FIG. 14(a)).

Next, a mask layer 7 of SiO2 is formed on the contact layer 60.
2 is formed, and using this mask layer 72 as a mask, the side surface of the element is etched to form a mesa shape, and from the side surface of this mesa shape, Z
Diffuse n. Then, Zn is diffused from the lateral direction,
The natural superlattice state in the hatched region is destroyed and disordered (FIG. 14(b)).

Thereafter, an electrode layer 64 and an electrode layer 66 are formed to complete the semiconductor laser (FIG. 14(C)).

As described above, in this embodiment, after forming into a mesa shape, impurities are diffused to make the structure disordered, so that the active region of the active layer can be formed to have a desired width.

The present invention is not limited to the above-mentioned embodiments, and various modifications are possible.

For example, in the above embodiment, Zn was introduced to destroy the natural superlattice state and make it disordered, but a P-type impurity other than Zn may be introduced. Furthermore, the p-type layer and n-type layer of the above embodiment may be reversed and n-type impurities may be introduced.

In addition, GaAs is a substrate that can form a natural superlattice.
It is not limited to the substrate, as long as elements with substantially different atomic radii are present on the surface at the same time. For example, G
A crystal containing an element selected from In, As, P, and sb for a (GaIn, GaAs, GaP, Ga5b)
, or a crystal containing elements carried from Ga, Aj, As, P, Sb to In (InGa, InAj,
The surface orientation can be selected using InAs, ■nP, In5b) as a substrate.

[Effects of the Invention] As described above, according to the present invention, a semiconductor laser with transverse mode control can be manufactured extremely easily.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a semiconductor laser according to a first embodiment of the present invention, FIG. 2 is a process diagram of a method for manufacturing a semiconductor laser according to a second embodiment of the present invention, and FIG. 3 is a cross-sectional view of a semiconductor laser according to a second embodiment of the present invention. FIG. 4 is a process diagram of a method for manufacturing a semiconductor laser according to a fourth embodiment of the present invention. FIG. 5 is a process diagram of a method for manufacturing a semiconductor laser according to a fifth embodiment of the present invention. 6 is a process diagram of a method for manufacturing a semiconductor laser according to a sixth embodiment of the present invention. FIG. 7 is a process diagram of a method for manufacturing a semiconductor laser according to a seventh embodiment of the present invention. , FIG. 8 is a process diagram of a method for manufacturing a semiconductor laser according to an eighth embodiment of the present invention, FIG. 9 is a cross-sectional view of a semiconductor laser according to a ninth embodiment of the present invention, and FIG. 11 is a process diagram of a method for manufacturing a semiconductor laser according to a 11th embodiment of the present invention; FIG. 12 is a process diagram of a method for manufacturing a semiconductor laser according to a 12th embodiment of the present invention FIG. 13 is a process diagram of a method for manufacturing a semiconductor laser according to a thirteenth embodiment of the present invention. FIG. 14 is a process diagram of a method for manufacturing a semiconductor laser according to a fourteenth embodiment of the present invention. FIG. 15 is a sectional view of a conventional semiconductor laser, and FIG. 16 is a sectional view of a conventional semiconductor laser. In the figure, 10...-n-GaAs substrate 12... cladding layer (n-(Aj a, s Gao, y) o, s
I no, s P )14-...Active layer (GaI
nP) 14a... Active region 16... Cladding layer (P (AjO,7Gao,i) o, s I n
o, s P) 18... Buffer layer (p-GaInP)
20-...Contact layer<p GaAs)21-...
Impurity layer (n-GaAs) 22... Electrode layer (A u / Z n / A u
) 24-... Electrode layer (A u G e / A u )
26...Mask layer (S i 02) 28-... High concentration impurity layer (p''-GaAs) 30...
- Second cladding layer (p-Aj xGal-xAs (x=0.4-0.
7)) 32...Mask layer (Sin2) 40...-p-GaAs substrate 41...Buffer layer (P-GaInP) 42...
Cladding layer (p-(AjO,?Cra6.1) I nP)
43... Active layer (GaInP) 43a... Active region 44... Clad layer (n (Aj(1,7Gao, 5) I n
P ) 45--Contact layer (n-GaAs) 46-
...Mask layer (SiO□) 47...8102 layer 48...Electrode layer (A u G e / A u ) 4
9... Electrode layer (A u / Z n / A u
)50-p-GaAs substrate 52...Buffer layer (p-GalnP) 54...
Cladding layer (P (Aj o, s Gao, s ) I nP
) 56... Active layer (GalnP) 56a... Active region 58... Cladding layer (n (Ano, s Gao, s)
InP) 60--Buffer layer (n-GaA
s) 62 ・:7 contact layer (n-GaAs) 64-・
- Electrode layer (AuGe/Au) 66-... Electrode layer (A u / Z n / A u
>68...Mask layer (Si02) 70...High concentration impurity layer (P" GaAs) 72.
...Mask layer (SiOz) 100--n-GaAs substrate 102...
Buffer layer (n-GaAs) 104--Clad layer (
n-AjGaI nP) 106...Active layer (GaI
nP) 108-...Clad layer (Aj Gal nP) 110
...Clad layer (p-AjGaAs >112 ・
...Contact layer (p-GaAs) 113...S i
s N 4 layer 114 ... Electrode layer (T L / P t / A
u) 116... Electrode layer (AuGe/Au) 120
-GaAs substrate 122--Buffer layer (n-GaAs) 124...
First cladding layer (n (Ajo, *Gao, 2) o, s I n
o, s P) 126...Second cladding layer (n'' (Aj O, 4Gao, a) o, s I
no, s P ) 128...Active layer (Ajo, +5 Gao, ms) o, s I no, s
P)130...Second cladding layer (p-(Aj6.4 Gao, 4) o, s
I no, s P) 132... Etching stopper layer (Ajo, +sG ao, ss) o, s I no,
s P )134...first cladding layer

Claims (1)

[Claims] 1. An active layer is formed by one-time vapor phase growth on a compound semiconductor substrate having a crystal surface in which elements having substantially different atomic radii are simultaneously exposed, and the active layer is grown naturally. The active layer is characterized by comprising a step of bringing the active layer into a superlattice state, and a step of selectively destroying the natural superlattice state of the active layer to disorder it, and forming an active layer in which a striped natural superlattice state remains. A method for manufacturing a semiconductor laser. 2. The method for manufacturing a semiconductor laser according to claim 1, wherein the substrate is tilted by 0 to 15 degrees in the [100] direction (100
) surface GaAs substrate, the active layer is made of GaInP, and the active layer is sandwiched between upper and lower cladding layers made of AlGaInP. 3. The semiconductor laser manufacturing method according to claim 1 or 2, wherein the disordering step destroys the natural superlattice state by diffusing impurities using a striped mask layer as a mask. Laser manufacturing method. 4. The method of manufacturing a semiconductor laser according to claim 1 or 2, wherein the disordering step involves destroying the natural superlattice state by ion-implanting impurities and then performing activation annealing. manufacturing method. 5. The semiconductor laser manufacturing method according to claim 1 or 2, wherein the disordering step destroys the natural superlattice state by locally irradiating a laser beam or an electron beam. manufacturing method.