JPS60167488A - Semiconductor laser device - Google Patents

Abstract

PURPOSE:To obtain the titled device of high-output and high-reliability oscillating on stable basic lateral modes also during high output action by a method wherein a semiconductor layer of the second conductivity type is provided on a semiconductor substrate of the first conductivity type having a mesa stripe, and thereafter two mesa stripes are formed. CONSTITUTION:A mesa stripe 10-2 is formed on the P-GaAs substrate 1-1, and N-GaAs 2 is grown so that the surface may become flat. Next, the two mesa stripes 10-3 are formed in such a manner that a groove 7 is present above the mesa stripe 10-2 on the substrate 1-1. Then, a P-GaAlAs clad layer 3, a GaAlAs active layer 4, an N-GaAlAs clad layer 5, and an N-GaAs cap layer 6 are successively grown. In this structure, inner current stricture is realized by a current stricture layer 2, and current flows in concentration to the light emitting region. Besides, a double hetero structure is formed on the two mesa stripes 10-3; therefore, an active layer 4 excellent in crystallinity and composition uniformity can be grown with good reproducibility.

Description

[Detailed description of the invention] [Field of application of the invention] The present invention provides a high output and highly reliable semiconductor laser device (1). Regarding the location.

[Background of the invention]

Problems with conventional high-power semiconductor lasers will be explained with reference to FIGS. 1 and 2. FIG. 1 shows an example of an internal current confinement type laser. In the figure, ■-1 is a p-GaAs substrate, 2
is n-GaAs current confinement layer, 3 is p-GaA
n As cladding layer, 4 is GaA Q As active layer,
5 is n-GaA 11 As cladding layer, 6 is n-
In the GaAs cap layer, 7 is a groove, 8 is an n-electrode, and 9 is an n-electrode. In this structure, the current confinement layer 2 causes the current to flow in a concentrated manner in the light emitting region, so that the gain distribution is less likely to become spatially non-uniform, and the fundamental transverse mode can be maintained to some extent even in high output operation. However, in order to achieve even higher output, the active layer 4 must be made as thin as 0.04 to σ, 06 μm. A liquid layer growth flow is applied to the substrate 1-1 having the groove 7 as shown in FIG. 1 and the current confinement layer 2.
It is difficult to grow such a thin active layer 4 with good crystallinity and reproducibility.

FIG. 2 is an example of a laser with a double (2) terror structure on two mesa stripes. In this case, an n-GaAs substrate 1 having two mesa stripes 10-1
Even at the stage where the cladding layer 5 has finished growing on -2, the parts above the two mesa stripes 10-1 and the groove 7 are higher than the other parts. Therefore, due to the characteristic of liquid phase growth that the growth rate is slower in high places than in low places, the growth time of the light emitting region of the active layer 4 becomes longer. Therefore 0.04
Since the growth time is long even for a thin layer of ~0.06 μm, the crystallinity and composition are uniform, and the thickness can be easily controlled. However, current confinement is achieved by providing a diffusion region 11, and compared to the case of internal current confinement shown in FIG. The disadvantage is that it is easily deformed.

[Purpose of the invention]

An object of the present invention is to provide a high-output, highly reliable semiconductor laser device that oscillates in a stable fundamental transverse mode even during high-output operation.

[Summary of the invention]

(3) As mentioned above, in the conventional internal current confinement type, it is difficult to make the active layer thin, and the structure in which a double hetero is formed on two mesa stripes has a problem in terms of current confinement. Therefore, it was necessary to devise an element structure in which a double heterostructure is formed on two mesa stripes and internal current confinement is possible. The present invention relates to such a laser structure. Hereinafter, the present invention will be explained in detail using FIG. 3. FIG. 3 shows a GaAs-
This figure shows a cross-sectional structure of a GaAflAs-based semiconductor laser. In the figure, 10-2 and 10-3 indicate mesa stripe portions. In this structure, internal current confinement can be realized by the current confinement layer 2, and the current flows intensively to the light emitting region. Therefore, even if the optical output is large to some extent, the gain distribution in the central portion of the light emitting region is not easily depressed, and the fundamental transverse mode is kept stable. In addition, since a double heterostructure is formed on the two mesa stripes 10-3,
An active layer with excellent crystallinity and uniform composition can be grown with good reproducibility.

(4) As described above, the present invention makes it possible to realize a high-output, highly reliable semiconductor laser in which the fundamental transverse mode is maintained up to a higher optical output than conventional lasers.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIG.

FIG. 4 shows GaAs-GaA, which is an embodiment of the present invention.
2 is a method for manufacturing a j2 As-based index-guided semiconductor laser and a cross-sectional view thereof. FIG. First, as shown in figure (a), p-
A height of 1.7 pm and a width of 1 on the GaAs substrate 1-1.
0. A mesa stripe 10-2 having a thickness of approximately 100 nm is formed using a phosphoric acid-based etching solution. As shown in the figure (b), n-GaAs 2 (Te) is grown by liquid phase growth.

4X10CI11') was grown so that the surface was flat. At this time, the thickness of nGaAs2 is 0.8 μm on the mesa stripe 10-2 and 2.5 μm elsewhere. Next, two mesa stripes 10-3 are formed using a phosphoric acid etching solution as shown in FIG. The etching depth is about 1.5 μm (5), and the width of each mesa stripe is 10 μm.
The distance between the mesa stripes, that is, the width of the groove 7 is 4 μm. The position of this groove is n-GaAs substrate 1-1
It is sufficient if it is on the upper mesa stripe 10-2, and there is no problem even if some misalignment occurs in the photo-I/resist process. Then, by the second liquid phase growth method, P Gao,
5sAI2o4sA5 cladding layer 3 (Z n + 7
X 1017cm-”) t Ga686A Qn, H
4As active layer 4 (undoped) HnGao,
s s A Q O, 4s A s cladding layer 5 (T
e, 1.5X 10"CIl+-3), n-G
aAs cap layer 6 (T e, 1.5X 10 c
m3) is grown sequentially as shown in (d). Here, the thickness of the P cladding layer 3 is 0.0 mm on the mesa stripe 10-3.
3 μm, and the thickness of the active layer on groove 7 is 0.05 μm.
It is. Finally, a p-electrode 8 and an n-electrode 9 are respectively formed as shown in the figure. In this example, the oscillation wavelength is 0,
A device with a visible wavelength of 78 μm, a fundamental transverse mode maintained up to an optical output of 30 mw CW, and an average life of 3000 hours or more at an optical output of 30 mw CW and a temperature of 70° C. was obtained with good reproducibility.

(6) The semiconductor laser device according to the present invention can be similarly applied to laser materials other than GaApAs, such as InGaAsP and InGap.

〔Effect of the invention〕

According to the present invention, the gain distribution is less likely to become spatially non-uniform due to internal current confinement, and since a double heterostructure is formed on two mesa strips, a thin utilization layer with excellent crystallinity is provided with good controllability. It will be done. Therefore, according to the present invention, a high-output, highly reliable semiconductor laser can be manufactured with good reproducibility. As a result, a fundamental transverse mode visible semiconductor laser with an optical output of 30 mw CW was obtained, and the average lifespan was 30 mw CW.
W at +70°C for more than 3000 hours. Therefore, it has become clear that the present invention is considerably effective in realizing a high-output and highly reliable semiconductor laser.

[Brief explanation of drawings]

Fig. 1 is a cross-sectional view of a conventional internal current confinement type laser, Fig. 2 is a cross-sectional view of a conventional laser in which a double heterostructure is formed on two mesa stripes, and Fig. 3 is a cross-sectional view of a laser according to the present invention. A cross-sectional view and FIG. 4 are a method of manufacturing a laser according to the non-explosion (7) method and a cross-sectional view thereof. 1-1-p-Q a As substrate, l-2-n-G
aAs substrate, 2...n-GaAs current confinement layer, 3...p-GaA QAs cladding layer, 4-Ga
AQAs active layer, 5-n-GaAQAs cladding layer, 6-n-GaAs cap layer, 7...
Groove, 8...n electrode, 9...n electrode, 10-1°10
-2.10-3...Mesa stripe, 11...(8
)

Claims (1)

[Claims] After providing at least a second semiconductor layer of a second conductivity type on a first semiconductor region of a first conductivity type having a first mesa stripe, second and third mesa stripes are formed by an etching method. In this case, the groove between the second and third mesa strips is between the first mesa strips, and the first semiconductor region is exposed only in the groove, and the groove between the second and third mesa strips is
and a third mesa stripe of at least the first conductivity type on the first semiconductor region and the second semiconductor layer having the third mesa stripe.
a semiconductor layer, a fourth semiconductor layer having a larger refractive index and a smaller band gap than the third semiconductor layer, a fifth semiconductor of a second conductivity type having a smaller refractive index and a larger band gap than the fourth semiconductor layer; A semiconductor laser device characterized in that layers are sequentially provided.