JPH0316280A - Semiconductor light emitting element - Google Patents

Abstract

PURPOSE:To restrain laser oscillation and to realize a super luminescent diode(SLD) of large output by absorbing light emitted from a light emitting region in an absorption region. CONSTITUTION:A P-type GaAlAs clad layer 3, a P-type GaAlAs light guide layer 4, a GaAlAs active layer 5, an N-type GaAlAs clad layer 6, and an N-type GaAs contact layer 7 are made to grow one by one on a wafer which is provided with a groove. Etching is carried out from the water. A groove which reaches the active layer 5 is formed as a boundary between a section with a mesa and a section without it. The section with a mesa on a substrate becomes a light emitting region as a current is injected thereto. The section without a mesa functions as an absorption region since a current is not injected thereto. Light emitted from the light emitting region is absorbed when it proceeds to the absorption region, and is not fed-back to the light emitting region; laser oscillation is thereby restrained remarkably. It is possible to restrain laser oscillation and to acquire an SLD having large output in this way.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a semiconductor light emitting device used for optical measurement and the like.

Conventional technology In recent years, light-emitting devices called super-luminescent diodes (SLDs), which have lower coherence than semiconductor lasers and can provide higher light output than light-emitting diodes, have been used in the field of optical measurement such as optical fiber dielectrics. elements are in demand. In order to realize this SLD, it is necessary to use a semiconductor laser structure as the basis since it can obtain a large optical output, and a reflection suppressing coating (▲
Attempts have been made to suppress laser oscillation by applying R coating.

Problems to be Solved by the Invention However, the above structure has the following problems. In other words, in order to obtain a large optical output as an SLD, it is necessary to reduce the reflectance of the chip end face to an extremely low value of 0.1% or less, but ordinary ▲R coating alone can sufficiently reduce the reflectance of the chip end face. Therefore, laser oscillation occurs before sufficient optical output is obtained as an SLD.
was not obtained.

Means for Solving the Problems In order to solve the above problems, the semiconductor light emitting device as an SLD of the present invention has the following features.

(1) The active region in the semiconductor chip is divided in the optical axis direction into a light-emitting region into which current is injected and an absorption region into which no current is injected, and the light emitted from the light-emitting region is absorbed by the adjacent absorption region. , suppresses laser oscillation.

(2) In the above structure, a light guide layer is formed adjacent to the active layer, and the light emitting region and the absorption region each have independent active antinodes and have a continuous and common light guide layer.

action The operation of the above structure will be explained below.

Since no current is injected into the absorption region, the Fermi level is lower than that of the emission region where current is injected. Therefore, when the light emitted from the light emitting region goes to the absorption region, it is absorbed as the name suggests, and is not returned to the light emitting region. Therefore, laser oscillation is significantly suppressed (FIG. 1(a)).

1. According to the structure of item 2 above, the light emitting region and the absorbing region are separated from each other by electrodes, and the prx junction of the absorbing region is biased in the reverse direction, or the pn junction is short-circuited. Electrons and holes generated by light absorption can be quickly removed from the junction, preventing a decrease in light absorption ability (first step).
Figure (b)).

Embodiment An embodiment of the present invention will be described with reference to the drawings.

A mesa as shown in FIG. 2e) is formed on the p-type GaAg substrate 1 by etching. The width of the mesa is 16 μm, the height is 2 μm, and of the total chip length of 750 μl, the length of the part with the mesa is L &:=250 μm, and the length of the part without the mesa is Lp=500 μm. An n-type GaAs blocking layer 2 is formed on this substrate by a liquid phase epitaxial method.
The wafer was mesa-layered so that the mesa thickness was 0.7 μm and the mesa surface was flat, and a groove with a depth of 1.6 μm as shown in FIG. 2 was formed on the wafer. The bottom of the groove should reach the substrate on the mesa and stay within the blocking layer on the part without the mesa. On the wafer with this groove formed, p-type Ga▲1▲S
Cladding layer 3, p-type Ga▲1▲$ light guide layer 4, Ga▲
1. Continuously lengthen the ▲S active layer 6, the n-type G&▲IAs cladding layer 6, and the n-type G&▲S contact layer 7 (Fig. 2(C)).
). Etching is performed on the etched wafer to form a groove having a width of 1 opm and reaching the active layer 5. The position of the groove is the boundary between the part with the mesa and the part without it, as shown in FIG. 2 (+1).

In the 8LD fabricated as described above, a portion of the substrate with a mesa serves as a light-emitting region because a current is injected therein, and a portion without a mesa serves as an absorption region because no current is injected therein. By applying a forward bias to the pn junction in the light emitting region and a reverse bias to the pn junction in the absorption region, this device has a low coherence with a spectral width of 2Qnll or more, and a large output with a maximum optical output of 1 esmW. S with
L! )was gotten.

Effects of the Invention As described above, in the semiconductor light-emitting device of the present invention, the active region within the semiconductor chip is divided in the optical axis direction into a light-emitting region into which current is injected and an absorption region into which current is to be injected, and the active region is separated from the light-emitting region. By absorbing light in adjacent absorption regions, it is possible to significantly suppress laser oscillation and realize a high-output SLD, which has great practical value.

[Brief explanation of the drawing]

Figures 1 (IL) and (b) are cross-sectional views when the optical axis of a semiconductor light emitting device according to an embodiment of the present invention is viewed from the side, and Figures 2 (a) to (d) are cross-sectional views of the embodiment of the present invention. FIG. 3 is a process diagram showing a method for manufacturing an element. 1...p-type eaAs substrate, 2...◆・n-type Ga
As blocking layer, 3...p-type Ga▲1▲S
Clad layer, 4...p-type G&▲IAs optical guide layer %5...Ga▲1▲S active layer, 6...
...n-type Ga▲work▲S cladding layer, 7...n-type G
aAs contact layer.

Claims (2)

[Claims] (1) The active region in the semiconductor chip is divided in the optical axis direction into a light-emitting region into which current is injected and an absorption region into which no current is injected, and the light emitted from the light-emitting region is absorbed by the adjacent absorption region. , a semiconductor light emitting device characterized by suppressing laser oscillation. (2) A light guide layer is formed adjacent to the active layer, and the light emitting region and the absorption region each have an independent active layer and a continuous common light guide layer. The semiconductor light emitting device according to item 1.