JPS626677B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improvements in striped semiconductor light emitting devices used as light sources for optical communications and the like.

Conventionally, a so-called planar stripe structure having a Zn diffusion region to form a stripe is known as a stripe type semiconductor laser, but this laser has a structure in which laser light is guided to a gain region by current excitation. Because of this, it has the disadvantage that kinks occur in the optical output and current characteristics due to non-uniform current flow, temperature distribution, etc., and the transverse mode becomes unstable.

Therefore, a laser having a channeled substrate planar (CSP) structure has been proposed, which is equipped with a light guide mechanism to stabilize the transverse mode. This laser has the configuration seen in FIG. That is, in the figure, 1 is the substrate,
1' is a groove formed in the substrate 1, 2 is a first cladding layer, 2' is a protrusion, 3 is an active layer, 4 is a second cladding layer, 5 is a contact layer, and 6 and 7 are electrodes.
In this laser, the light is mainly guided through the active layer directly above the protrusion 2', so that the transverse mode is said to be stable. However, this is an ideal case, and in reality, the shoulders of the grooves 1' (see arrows), which were formed in a sharp manner when the first cladding layer 2 was grown by liquid phase epitaxial growth, were formed in an ideal manner. Since it melts back into the melt and causes so-called sagging, it is not possible to provide the expected light guide function.

The present invention attempts to reliably stabilize the transverse mode by adding an extremely simple structural modification to the semiconductor light emitting device as described above, and this will be explained in detail below.

2 is a front explanatory view of the main part of an embodiment of the present invention, FIG. 3 is a side sectional view of the main part taken along line A-A' in FIG. 2 and seen in the direction of the arrow, and FIG. Line B in the diagram
It is an explanatory side cross-sectional view of the main part taken along B' and viewed in the direction of the arrow, and the same parts as those described in FIG. 1 are indicated by the same symbols. Note that this embodiment relates to a GaAs-based laser.

The difference between this embodiment and the conventional example shown in FIG.
A groove 1'' is formed outside the stripe area, and a cladding layer 2, an active layer 3, a cladding layer 4,
The four layers of the contact layer 5 are epitaxially grown in succession.

According to such a configuration, the light leaking from the active layer 3 to the cladding layer 4 is scattered in a portion other than the stripe area set on the substrate 1 (therefore, the cladding layer 4), resulting in a loss. The directional mode is what is stabilized.

In the case of this example as well, when growing the first cladding layer 2, shoulder sagging of the groove 1' occurs due to melt back, but since it is unrelated to scattering loss, such shoulder sagging occurs. You can also make things work properly.

FIG. 5 is a front explanatory view of the main part of another embodiment, and FIG. 6 is a side cross-sectional view of the main part taken along line A-A' in FIG. The same parts as those explained in connection with FIG. 4 are indicated by the same symbols.

This example relates to an InP-based laser,
In this case, since the substrate 1 plays the role of a cladding layer, the first cladding layer 2 shown in FIGS. 2 to 4 does not exist. Therefore, the influence of the groove 1' formed in the substrate 1 directly affects the active layer 3, which is more effective.

As can be seen from the above description, according to the present invention, the substrate is provided with a substrate having enough irregularities formed on the surface excluding appropriately set stripe areas to scatter light generated in the active layer and cause a loss. According to this semiconductor light emitting device, even if shoulder sagging of the groove occurs due to melt back when growing the first cladding layer or active layer, the lateral mode can be reliably stabilized. can do.

[Brief explanation of the drawing]

Fig. 1 is an explanatory front view of main parts of a conventional example, Fig. 2 is a front view of main parts of an embodiment of the present invention, and Fig. 3 is a side sectional view of main parts taken along line A-A' in Fig. 2. , FIG. 4 is an explanatory side cross-sectional view of the main part taken along line B-B' in FIG. 2, and FIG.
The figure is a front explanatory view of the main part of another embodiment, and FIG.
It is an explanatory side sectional view of a main part in line AA' of a figure. In the figure, 1 is a substrate, 2 is a cladding layer, 3 is an active layer, 4 is a cladding layer, 5 is a contact layer,
1' and 1'' are grooves.

Claims (1)

[Claims] 1. A semiconductor light-emitting device comprising a substrate having enough irregularities formed on its surface, excluding appropriately set stripe regions, to scatter light generated in an active layer and result in loss.