JPS62296583A - Semiconductor laser device - Google Patents

Abstract

PURPOSE:To thin the film thickness of an active layer, and to realize the increase of an output by forming a stepped section to a P-type clad layer and bringing the width of the flat section of the stepped section to 140mum or less. CONSTITUTION:A mesa la is shaped onto a P-type GaAs substrate 1, an N-type GaAS current constriction layer 2 is grown and ridges 2a, 2b are formed, a P-type Al0.40Ga0.60As clad layer 3, an Al0.08Ga0.92As active layer 4, an N=type Al0.40Ga0.60As clad layer 5 and an N-type GaAs contact layer 6 are grown onto the ridges in succession through a liquid phase epitaxial growth method, and an N side electrode 7 and a P side electrode 8 are formed through evaporation. Growth on the ridges 2a, 2b is inhibited as compared to the side surfaces of the ridges 2a, 2b by the anisotropy of crystal growth, and the P-type clad layer 3 is grown flatly in the spread of width W on the ridges 2a, 2b. When the active layer 4 is grown on the layer 3, the growth of the active layer 4 on the flat section of the P-type clad layer 3 is suppressed largely. The width W of the flat section of the P-type clad layer 3 is brought to 140mum or less, thus allowing the thinning of the film thickness of the active layer 4, then realizing the increase of an output.

Description

[Detailed description of the invention] 3. Detailed description of the invention Industrial applications The present invention relates to a semiconductor laser device.

BACKGROUND OF THE INVENTION In recent years, semiconductor laser devices have become extremely important as light sources for optical fiber communications, for recording and reproducing optical disk memories, and as devices that form the heart of optical information processing equipment, such as laser printers. ing.

Semiconductor lasers are being used one after another in a variety of fields, and various structures have been considered, with the currently mainstream structure being an internal stripe type. be.

An example of the internal stripe type structure is the structure shown in FIG. 1 is a p-type GaAs substrate, 2 is an n
Type G a As electric a narrow? layer, 3 is p-type Aeo,
aJao, eD" cladding layer, 4 is "0.08GaO,
92" active layer, 5 is n-type Aeo, 40" 0.60AB
cladding layer, 6 is n-type GaAs cap layer, 7
is the n-side electrode, and 8 is the p-side electrode.

Problems to be Solved by the Invention However, when the above structure is formed by liquid phase epitaxial growth, the active layer 4 is grown on the flat layer 3, so it is difficult to make the active layer thin. Therefore, it has been difficult to achieve high output.

In view of the above-mentioned drawbacks, the present invention provides a semiconductor laser device in which the active layer can be made thinner and higher output can be realized.

Means for Solving the Problems In order to solve the above problems, the semiconductor laser device of the present invention is constructed by providing a step in the p-type rad layer and making the width of the flat part 140 μm or less. There is.

Function: With this configuration, it is possible to form a thin active layer on the cladding layer, and high output can be achieved.

EXAMPLE Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 1 shows a cross-sectional view of a semiconductor laser device according to an embodiment of the present invention. 1 is a p-type GaAs substrate, 1a is a mesa, 2 is an n-type GaAs current confinement layer, and 2a and 2b are ridges. By this liquid phase epitaxial growth method, p-type Aeo, 4oGao, eoAB cladding layer 3, Aeo, os Gao, 92A
8 active layer 4. n-type AeO, 40Ga0, 60AS cladding layer5. An n-type GaAs contact layer 6 was sequentially grown, and an n-side electrode 7 and a p-side electrode 8 were formed by vapor deposition. Due to the anisotropy of crystal growth, ridge 2a,
Growth on ridge 2b is suppressed compared to the side surfaces of ridges 2a and 2b. The p-type cladding layer 3 grows flat on the ridges 2a and 2b with a width W, and when the growth time of the p-type cladding layer 3 is lengthened, the growth is very slow on the ridges 2a and 2b, so the width W increases. It grows so that it spreads.

When the active layer 4 is grown on this soil, the p-type cladding layer 3
The growth of the active layer 4 on the flat portion of the substrate is greatly suppressed.

FIG. 2 shows the relationship between the width W of the flat portion of the p-type cladding layer 3 and the thickness d of the active layer 4 grown on the flat portion. The growth temperature was 846°C, the degree of supersaturation was 5°C, and the growth time was 2 seconds. When the width W is 140 μm or more, the controllability of the active layer thickness d becomes poor and the thickness becomes large. Although it is possible to make the active layer thinner by shortening the growth time, it is not practical if the growth time is less than 2 seconds because the reproducibility of the film thickness deteriorates. FIG. 3 shows an investigation of the relationship between the active layer thickness d and the top surface fracture level. This does not have an edge protection film attached. As the thickness of the active layer becomes thinner, the light confinement coefficient within the active layer becomes smaller, so the light seeps out into the cladding layer.As a result, the optical power density at the end face decreases and the level of destruction increases. do. When the active layer thickness d becomes 0.06 μm or more, the level of destruction decreases rapidly. The width W of the flat portion of the p-type rad layer that can realize an active layer thickness d of 0.06 μm or less is 140 μm or less, and a high output can be achieved at this time.

As described above, the width W of the flat part of the p-type rad layer is set to 14
By setting the thickness to 0 μm or less, it is possible to make the active layer 6 pages thinner, thereby realizing high output, which has great practical effects.

[Brief explanation of drawings]

Fig. 1 is a cross-sectional view of a semiconductor device according to an embodiment of the present invention, Fig. 2 is a characteristic diagram showing the relationship between the width of the flat part of the cladding layer and the active layer thickness, and Fig. 3 is the active layer thickness. FIG. 4 is a sectional view of a conventional semiconductor laser device. 1 ・-・-p-GaAs substrate, 2 ・-=-n −G
aAs layer, 3---... p-AeGaAs cladding layer, 4 =--AeGaAs active layer. Name of agent: Patent attorney Toshio Nakao and 1 other person6-
1〉GukuF噌ζ52Fig.
20060 fo.

Claims (1)

[Claims] A mesa stripe-like structure is formed on a GaAs substrate of one conductivity type, a GaAs layer of a conductivity type opposite to the one conductivity type is formed on the substrate on which the mesa stripe structure is formed, and a GaAs layer of the opposite conductivity type is formed on the substrate on which the mesa stripe-like structure is formed. A ridge stripe structure is formed in the GaAs layer in parallel to the upper part of the mesa stripe structure, and a groove parallel to the mesa stripe structure is formed in the center of the ridge stripe structure. is formed so as to reach the mesa stripe-like structure,
The cladding layer of one conductivity type is formed on the substrate on which the ridge stripe-shaped structure is formed, and the upper surface of the one-conductivity type cladding layer above the ridge stripe-shaped structure is flat; A semiconductor laser device characterized in that the width of a flat portion of the upper surface of the conductivity type cladding layer is 140 μm or less, and an active layer, the opposite conductivity type cladding layer, and a cap layer are formed on the one conductivity type cladding layer.