JPH084176B2 - Method for manufacturing semiconductor laser device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a semiconductor laser device required for optical fiber communication, an optical measurement system, or optical information processing such as an optical disk. The present invention relates to a method for manufacturing a monolithic multi-wavelength semiconductor laser device which is required for multiplexing and multifunctioning.

2. Description of the Related Art Semiconductor lasers have entered the stage of practical application, centering on optical fiber communications and optical disks, and have entered the age of mass production. Research and development is aimed at higher performance. A semiconductor laser array having a plurality of wavelengths is required as one of the directions. As a conventional proposal, semiconductor laser chips with different wavelengths are separately manufactured, and they are arranged and bonded on the same submount to form a module 2
Wavelength lasers or active layers that perform the same epitaxial growth on the same substrate and recombine injected carriers to emit light have the same composition and the same thickness, but the period of the diffraction grating that determines the wavelength is set for each laser. On the other hand, a multi-wavelength DFB laser array in which the wavelength is gradually shifted has been proposed. However, this laser has five waves and a wavelength interval of about 50 Å, and although a large multiplicity can be obtained, the wavelength separation method remains difficult.

FIG. 4 shows a sectional structure of another example of the two-wavelength laser. AlGaAs clad layer 21, AlGaAs on GaAs substrate 20 with a gap
An active layer 22 and an AlGaAs cladding layer 23 are sequentially grown to form a laser structure. The active layer 25 immediately above the gap has a large film thickness and a small Al composition, while a flat film having a small film thickness and a high Al composition grows. Therefore, when the separation layer 26 and the electrode 27 are provided to form a laser structure, the laser on the step emits laser light having a longer wavelength than in the case where the flat portion is the active layer.

However, also in this case, the wavelength intervals of the emitted laser light are narrow, and it is difficult to control the wavelength difference to an arbitrary value.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention As described above, in the related art, it was difficult to control the wavelength interval widely and arbitrarily.

Therefore, the present invention is intended to set the wavelength interval to be wide and arbitrary, and to reduce the number of times of epitaxial growth, which is the most important step in manufacturing, as much as possible.

Means for Solving the Problems The present invention provides a buried layer of a laser active layer portion in a laser array structure in which at least two wavelengths of semiconductor lasers having AlGaAs, InGaAsP, InGaP, and AlGaInP as active layers are arranged.
It is intended to be a common layer of AlGaInP or AlInP. As a result, an arbitrary laser can be set on the same substrate, and the buried layer can be shared by all the lasers by one growth.

That is, the method for manufacturing a semiconductor laser device of the present invention is
AlGaAs (including GaAs) or InGaAsP or AlGaInP (including InGaP) lattice-matched with GaAs on a GaAs substrate
A step of arranging a plurality of double heterojunctions as an active region in which injected carriers are recombined to generate light so as to generate light of different wavelengths, and a horizontal stripe-shaped buried of the active region is formed of GaAs. Lattice-matching AlGaInP (AlIn
(Including P, InGaP) or InGaAsP layer is performed at the same time.

Action In the present invention, a plurality of different lasers can be easily formed on the same substrate by selecting an appropriate combination of materials and compositions to be lasers. By matching the substrate and the lattice constant and forming the buried clad layer in common with a material having a large band gap, it becomes possible to produce a high-quality semiconductor laser.

Embodiment FIG. 1 shows a perspective view of an embodiment of this patent. GaAs substrate 1
Two embedded semiconductor lasers are monolithically formed on one chip. The first semiconductor laser 13 is a GaAlAs-based oscillation wavelength λ ₁ = 800 nm, and the second semiconductor laser 14 is InGaAs.
In the P system, λ ₂ = 700 nm. The manufacturing process of the laser of FIG. 1 is shown in a sectional structure in FIG. 2, and its composition is shown in FIG.
-InP system, GaP-InP-InAs-GaAs system, GaAs-InAs-AlAs
The system is shown in a three-phase diagram. In FIG. 3, ABCD is Ga
The composition is lattice-matched with As, and A, B, ... I are the compositions at each point.

 The manufacturing method will be described along the second manufacturing process.

AlGaAs on n-GaAs substrate by liquid phase epitaxy using Ga as solvent
Cladding layer 2 (composition E), AlGaAs active layer 3 (F), AlGaA
s Clad layer 4 (E) is sequentially grown (FIG. 2 (a)). Next, a SiO ₂ mask 15 is formed on a part of the growth layer,
A part of the growth layer is removed by etching (FIG. 2 (b)). The etched substrate remains the mask
The P-InGaAsP layer is epitaxially grown on a portion where the P-InGaAsP layer is removed by etching by a liquid phase growth method using an In solvent. n-InGaP
Cladding layer 5 (B), InGaAsP active layer 6 (G), P-InG
The aP clad layer 7 (B) is sequentially grown (FIG. 2 (c)). Figure 2 (d) of the grown epitaxial layer
As shown in FIG. 16,17
Indicates a SiO ₂ mask. The P-InGaP burying layer 8 and the n-InGaP burying layer 9 are sequentially grown on the wafer etched on the mesa by a liquid phase growth method. (FIG. 2 (e)). Further, each laser is separated by inserting a separation etching between each element (FIG. 2 (f)). By applying each electrode to this, a two-wavelength monolithic array laser as shown in the first perspective view is constructed.

In this way, a two-wavelength laser can be constructed by three epitaxial growth steps. As shown in FIG. 3, layers having different constituent elements or different compositions are used as the laser active portion by properly selecting the composition and the constituents, and the cladding layers of both lasers are simultaneously formed in a lattice-matched state. It becomes possible to do. With this configuration, Al
A GaAs laser and an InGaAsP laser were constructed on the same substrate, and a two-wavelength laser with a large wavelength interval of λ ₁ = 800 nm and λ ₂ = 700 nm became possible.

As a second embodiment, as shown in FIG. 2 (b), AlGa
As-based growth is similarly performed, and the second epitaxial growth of FIG. 2 (c) is performed using n-Al using the metal organic chemical vapor deposition method.
GaInP clad layer 5 (H), AlGaInP active layer 6 (I), P
-AlGaInP clad layer 7 (H) is formed. (CH ₃ ) ₃ Al, (CH ₃ ) ₃ In, (CH ₃ ) ₃ Ga and PH ₃ are H
₂ is used as a carrier gas. Further, by using MO-CVD method, P-AlGaInP8 (H), n-AlGa as a buried layer is formed.
By forming InP9 (H), the structure of FIG. 2 (f) can be realized without breaking the lattice matching. in this way,
An AlGaAs laser and an AlGaInP laser can be configured with the same clad on the same substrate, and it becomes possible to integrate a wavelength 600 nm band laser and a 700 to 800 nm band laser.

Similarly, it is possible to monolithically integrate an AlGaInP laser and an InGaAsP laser, and it is also possible to integrate lasers having different wavelengths by changing the composition of lasers having the same constituent elements. It goes without saying that not only two wavelengths but also three or more wavelengths can be similarly configured.

As described above, according to the present invention, AlGaAs is formed on a GaAs substrate.
It is possible to easily realize a monolithic structure of a multi-wavelength laser having an active layer of InGaAsP system, InGaAsP system, or AlGaInP system by an arbitrary combination at an arbitrary wavelength. Furthermore, these lasers have the same composition of AlGa in the lateral buried layer of the laser active layer.
InP (including AlInP and InGaP) or InGaAsP layers can be formed, and the buried epitaxial process can be reduced.

From the application point of view, if you need to narrow down to a small spot such as optical disk read, use a short wavelength laser,
When high power such as erasing is required, it is possible to use different wavelengths such as AlGaAs series on the wavelength side.

[Brief description of drawings]

FIG. 1 is a perspective view of a multi-wavelength array laser obtained by the method of one embodiment of the present invention, FIG. 2 is a process cross-sectional view for explaining the multi-wavelength array laser manufacturing method of FIG. 1, and FIG.
The figure shows InP-GaP-GaAs-InP, AlP-InP-GaP, AlAs-GaAs-
FIG. 4 is a phase diagram of InAs and FIG. 4 is a sectional view of a two-wavelength laser array obtained by a conventional method. 1 ... GaAs substrate, 2 ... AlGaAs cladding layer, 3 ... AlGaAs
Active layer, 4 ... AlGaAs cladding layer, 5 ... n-InGaP cladding layer, 6 ... InGaAs active layer, 8 ... P-InGaP buried layer, 9 ... n-InGaP buried layer, 13 ... first Semiconductor laser, 14 ... Second semiconductor laser.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tomoaki Uno 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. 72) Inventor Hiroaki Yamamoto 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (56) Reference JP 63-227089 (JP, A) JP 62-296587 (JP, A) JP Sho 57-124489 (JP, A)

Claims (1)

[Claims] 1. An AlGaAs lattice-matched with GaAs on a GaAs substrate.
Alternatively, a step of arranging a plurality of InGaAsPs or AlGaInPs so that the injected carriers are recombined to form an active region for generating light so as to generate light of different wavelengths, and a horizontal stripe shape of the active region is formed. Embed
A method for manufacturing a semiconductor laser device, comprising the steps of simultaneously performing an AlGaInP or InGaAsP layer lattice-matched with GaAs.