JPH02260588A - Semiconductor laser and manufacture thereof - Google Patents

Abstract

PURPOSE:To distinguish a region in a wafer having a lightguide layer from the appearance by a method wherein, after a compound semiconductor thin film layer is built up, a group III metal film is built up while a light is applied to the parts other than a LOC region. CONSTITUTION:In order to build up a P-type Al0.35Ga0.65As lightguide layer 106, a light is applied to the part other than the neighborhood of the end surface of a resonator and the decomposition efficiency of TMA which is Al raw material for an MOCVD method is promoted to increase the Al composition. By applying the light, a light application layer 104 is converted into a P-type Al0.5Ga0.5As layer which has the same composition as a P-type cladding layer 107. After the semiconductor layer is built up, a growth temperature is lowered to 200 deg.C, carrier gas and TMA are introduced and the light is applied to the part other than the neighborhood of the end surface of the resonator. As TMA is hardly decomposed by heat at 200 deg.C, an Al layer 110 which is a group III metal film is built up by the photodissociation of TMA on the light-irradiated part only. With this constitution, the position of the lightguide layer in a wafer can be easily distinguished.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a semiconductor laser in which deterioration of the cavity end face is prevented.

[Conventional technology]

The main cross-sectional view of a semiconductor laser manufactured by the conventional technique is shown in Fig.
n-type A lo, 4sG ao, ssA S cladding layer, (03) Al1. , +sG ao, ssA
S active layer.

(06) P type A 2 o, as G a o, ss
A S light guide layer, (07) PgMAjl! o, a
A Gao, iAs cladding layer, and a (05) P-type GaAs cap layer are epitaxially grown in sequence by MOCVD. (06) P-type A lo, ssG a o,
When growing the ssA s optical guide layer, light is irradiated to a portion other than the vicinity of the resonator end face to promote the decomposition efficiency of TMA, which is the AI2 raw material of the MOCVD method, and increase the β composition. Upon light irradiation, the (04) light irradiation layer becomes P-type Aβ having the same composition as the (07) P-type cladding layer. s G a o, o
sA This becomes the S layer.

After epitaxial growth by MOCVD method, (08
) A P-type electrode and (09) an N-type electrode are deposited and folded for each chip to obtain a semiconductor laser having an end face LOC structure.

Since the obtained semiconductor laser has an LOC structure near the cavity end face, the optical density of the active layer at the cavity end face is reduced and facet deterioration is suppressed, and the optical density does not decrease in areas other than the end face. It is possible to suppress the increase in threshold current that occurs when the entire structure is formed into a LOG structure. Therefore, high output oscillation is possible.

[Problems to be Solved by the Invention] However, in the above-mentioned conventional technology, after manufacturing a compound semiconductor thin film layer constituting an edge LOC structure semiconductor laser using the MOCVD method, when folding it into a laser chip, the light guide in the wafer is removed. Since the location of the layer cannot be visually determined, grooves are etched to serve as landmarks in the single-crystal compound semiconductor substrate before growth, and ultraviolet light is irradiated to match the grooves, but etching the substrate is time-consuming and difficult. However, since the irradiation light is ultraviolet light, it is difficult to match the mask. The present invention is intended to solve these problems, and its purpose is to provide a semiconductor laser that can easily identify the location of a light guide layer in a wafer after growing a compound semiconductor thin film layer using the MOCVD method. and a manufacturing method thereof.

[Means for Solving the Problems] In order to solve the above problems, the semiconductor laser and the manufacturing method thereof of the present invention provide: (1) an end face L having a light guide layer only in the vicinity of the cavity end face;
In a semiconductor laser having an OC structure and manufactured by a step of irradiating light to a region other than the vicinity of the resonator end face during epitaxial growth of the optical guide layer, III It is characterized by having a group metal film.

(2) After the semiconductor layer constituting the semiconductor laser is grown by a growth method using an organic metal as a raw material, the Group III metal film is grown while being irradiated with light.

[Example] A main cross-sectional view of a semiconductor laser according to an example of the present invention is shown in FIG.
) n-type A 420.41G a o, ssA s cladding layer, (103) Aj2o, +5Gao, 5sAS active layer, (106) P-type A j! o, ssG ao
, aaA S light guide layer, (107) P-type Alo,s
Gao, s As cladding layer, (105) P-type GaA
The S cap layer is sequentially grown epitaxially by MOCVD.

(106) P-type A 12 o, ssG a o, s
When growing the sA s optical guide layer, light is irradiated to a portion other than the vicinity of the cavity end face to promote the decomposition efficiency of TMA, which is the Ag raw material for MOCVD, and increase the /1 composition.

By light irradiation, the (104) light irradiation layer becomes P-type A2°, s Ga a, s with the same composition as the (107) P-type cladding layer.
A: There will be 8 layers. After growing the semiconductor layer, increase the growth temperature to 20
The temperature is lowered to 0° C., only the carrier gas and TMA are flowed, and parts other than the vicinity of the resonator end face are irradiated with light. Since TMA hardly thermally decomposes at 200° C., a (110) Ag layer is deposited by photodecomposition of TMA only in the light irradiated area.

Figure 2 shows a main configuration diagram of a semiconductor laser manufacturing apparatus according to an embodiment of the present invention. Raw material gas is introduced from the raw material gas introduction system (209) into the reaction tube (210) and heated in (211). A compound semiconductor thin film is grown by pouring it onto a substrate. During the growth of the (106) light guide layer and the (1to)A42 layer, the ultraviolet light from the excimer laser (201) is
Shaped with a cylindrical lens (202) (203)
It is reflected by the mirror (204), made into a parallel beam by the synthetic quartz lens (205), and passed through the mask (206).
07) The substrate is focused by the reduction lens, and light is irradiated to a region other than the vicinity of the cavity end face of the semiconductor laser.

After depositing the (110) AJ2 layer, (11
1) Form a SiOs layer, etch the SiOs layer in stripes (ll'1) parallel to the resonator direction, and then add a (ios) p-type ohmic electrode, (101) on top of the SiOs layer.
A (109) n-type ohmic electrode is formed by vapor deposition on the n-type GaAs substrate side.

FIG. 3 is a diagram showing the semiconductor laser wafer before the folds. A resonator is formed by forming folds along a thin region of (312)II thickness other than the upper part of the (310)Aff layer, thereby obtaining a gain waveguide type end facet LOC structure semiconductor laser. In the obtained semiconductor laser, the optical density of the active layer decreases only in the vicinity of the cavity end face, suppressing the deterioration of the end face, and the optical density of the active layer does not decrease in the region other than the end face, and when the whole has a LOG structure. Since the increase in the threshold current can be suppressed, high output oscillation is possible.

In this example, A2 was used as the group III metal film, but any group III metal made from an organic metal, such as Ga or In, may of course be used. Since a step in film thickness occurs above the rib, the present invention is of course effective, and the region having the light guide layer can be determined by appearance.

[Effect of the invention 1 As described above, according to the present invention, after growing a compound semiconductor thin film layer, II
After epitaxial growth, a semiconductor laser wafer with an edge LOC structure is formed by depositing a Group I metal film.
When folding a laser chip, the location of the LOCfil region can be determined by its appearance, so there is a process of etching a groove to serve as a mark on the substrate before growth, and an alignment process to irradiate light to match the groove. This eliminates the need for the process.

This makes it possible to significantly shorten the manufacturing process. the result.

The yield is improved, and a long-life semiconductor laser with a high maximum optical output and suppressed deterioration of the resonator end face can be easily manufactured at a low manufacturing cost.

[Brief explanation of drawings]

FIG. 1 is a perspective view of a semiconductor laser in an embodiment of the present invention. FIG. 2 is a main configuration diagram of a semiconductor laser manufacturing apparatus in an embodiment of the present invention. FIGS. 3(a) and 3(b) are (a) a top view and (b) a main sectional view of a semiconductor laser wafer before the folds in an embodiment of the present invention. FIG. 4 is a main cross-sectional view of a conventional semiconductor laser. (101), (105), (108), (109), (111), (2l O (2l 2 (301), (401)... n-type GaAs substrate (305), (405)... P-type GaAs cap layer (30B), (408)...P-type electrode (309), (409)...n-type electrode...Si0g layer...cylindrical lens...mirror...synthetic quartz Concave lens...synthetic quartz convex lens...high frequency oscillator...raw material gas introduction system...reaction tube...exhaust system/ρ A'!Aloa;host%s 7 Death・7
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Claims (2)

[Claims] (1) End face L having a light guide layer only near the cavity end face
In a semiconductor laser having an OC structure and manufactured by a step of irradiating light to a region other than the vicinity of the cavity end face during epitaxial growth of the optical guide layer, III A semiconductor laser characterized by having a group metal film. (2) A method for manufacturing a semiconductor laser, which comprises growing a semiconductor layer constituting the semiconductor laser by a growth method using an organic metal as a raw material, and then growing the group III metal layer while irradiating it with light.