JPH04329678A - edge light emitting diode - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light emitting diode, and particularly to an edge light emitting diode used as a light source in fields such as optical communication, information processing, and measurement.

0002

2. Description of the Related Art In edge-emitting diodes, the most important issues are to suppress laser oscillation at low temperatures and to reduce temperature dependence. In conventional embedded edge-emitting diodes, in order to suppress stimulated emission components, a non-excited region is formed by preventing current from flowing at the rear of the active layer, and the stimulated emission components are absorbed in this region.
Measures have been taken to prevent stimulated emission components from returning to the excitation region by providing a portion where the active layer is not buried, or by providing an antireflection film to suppress reflection at the end face. However, these methods have drawbacks such as increased device length and complicated processes.

[0003] Also, from the viewpoint of improving yield, a structure that is simple and can suppress stimulated emission components is desired.

FIG. 3 is a perspective view of an example of a conventional edge-emitting diode whose rear end is obliquely etched after crystal growth, in response to this requirement. In the figure, 1 is a p-electrode, 2 is a p-InP single crystal substrate, 3 is a p-InP buffer layer, 4 is an n-InP block layer, 5 is a p-InP block layer, and 6 is p-InP cladding layer, 7 is InGaA
sP active layer, 8 an n-InP cladding layer, 9 an n-
A cap layer of InGaAsP, 10 is an n-electrode, 11 is an active region, and 12 is a slope portion formed by etching.

In the edge-emitting diode with this structure, the stimulated emission component seeping backward from the active region 11 is scattered by the slope portion 12, so that the component returning to the active region becomes extremely small, and laser oscillation is sufficiently suppressed. It is possible to do so. However, since the slope portion 12 is formed by etching, the element after crystal growth is exposed to acid, which poses a problem in terms of crystal protection, and cannot be said to be optimal. There is also the problem that the manufacturing process after the crystal growth is completed takes a long time.

[0006]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and realizes an edge light emitting diode in which a sloped portion can be formed without using a method of etching the device after crystal growth. The purpose is to

[0007]

SUMMARY OF THE INVENTION The present invention is an edge-emitting diode characterized in that the substrate has a stepped portion at the rear thereof, and a crystal growth layer is formed on the substrate.

[0008]

[Operation] An edge light emitting diode in which a slope is formed in advance by etching or the like on the rear of the substrate, and each layer is formed by crystal growth thereon has a slope at the rear. The slope portion scatters the stimulated emission light, and as a result, the stimulated emission component from the light extraction surface can be reduced. Crystal growth can naturally form slopes, so crystal protection can be achieved. Further, the process after the crystal growth is completed can be limited to electrode formation and substrate polishing to reduce the thickness of the substrate, so that the process can be simplified.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a perspective view of an embodiment of an edge-emitting diode according to the present invention. In the figure, parts similar to those in FIG. 3 are denoted by the same reference numerals, and description thereof will be omitted. 13 is an etched portion of the substrate, and 14 is a sloped portion formed by crystal growth.

A method of manufacturing the edge light emitting diode shown in FIG. 1 will be explained. ■ P-InP single crystal substrate 2 (10
0) A step of about several μm is created by etching in the x direction of the figure on the surface. In this case, grooves are formed on the wafer in a trapezoidal or triangular shape, and after crystal growth,
By cleaving from the center of the groove, the elements can be separated with the rear end faces facing each other. therefore,
Depending on the width of the groove formed by etching, a flat part may be formed at the end of the step at the rear of the substrate as shown in the figure, or a flat part may not be formed and the end may remain sloped to the end. be. ■ P-In on the above substrate 2
P buffer layer 3, n-InP block layer 4, p-I
An nP block layer 5 and an InGaAsP mask layer are crystal grown. (2) After crystal growth, an arrowhead-shaped groove is formed by etching along the y direction in the figure in the high step portion of the wafer, and the InGaAsP mask layer is removed. ■ P-InP is added to the wafer on which this block layer is formed.
cladding layer 6, active layer 7 of InGaAsP, n-In
P cladding layer 8, n-InGaAsP capping layer 9
Embed and grow. ■ Polish the back side of the substrate 2 and thin it to the desired thickness. ■P electrode 1 on the substrate side,
An n-electrode 10 is formed on the crystal growth side. ■ Separated into chips by cleavage.

[0011] In this way, there is no need for an etching process using acid after the buried growth is completed, which is advantageous in terms of protecting the crystal.

In addition, the composition of the n-InGaAsP cap layer 9 is changed to a crystal with a band gap smaller than the crystal with a composition of 1.3 μm constituting the active layer, for example, 1.55 μm.
InGaAsP with a composition of 1.67 μm, InGa with a composition of 1.67 μm
By using As, the cap layer itself that covers the slope portion becomes a light absorption region, and there is also the effect that the scattered light is absorbed by the surface.

FIG. 2 is a perspective view of another embodiment of the edge-emitting diode of the present invention. In the figure, parts similar to those in FIG. 1 are denoted by the same reference numerals, and explanations thereof will be omitted. In this embodiment, for example, SiO2 is patterned as an insulating film 15 on the cap layer 9, and a non-excited region is formed by preventing current from flowing in the rear part of the active layer 7, so as to absorb stimulated emission light. I made it. The unabsorbed components are scattered by the slope portion 14, as in the embodiment of FIG.

[0014] Note that the step of forming the step is different from that in the conventional edge-emitting diode described in FIG. In the edge-emitting diode of the invention, for example, a 2-inch wafer is used and the substrate is patterned so that each element is alternately oriented in opposite directions in each row, as described in section (2), at the wafer stage. This is desirable because the steps can be formed all at once by one etching, which is advantageous in terms of time and leads to cost reduction.

Although the above-mentioned embodiments have been described with respect to InGaAsP type edge-emitting diodes, it is clear that the present invention can be applied to edge-emitting diodes of other types as well.

[0016]

[Effects of the Invention] As is clear from the above description, according to the present invention, by forming the inclined portion on the substrate, a step can be formed at the rear of the element due to crystal growth, which is advantageous in terms of protecting the crystal. Moreover, it is possible to provide an edge light emitting diode whose manufacturing process can be simplified.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of an embodiment of an edge-emitting diode of the present invention.

FIG. 2 is a perspective view of another embodiment of the edge-emitting diode of the present invention.

FIG. 3 is a perspective view of an example of a conventional edge-emitting diode.

[Explanation of symbols]

1 p electrode 2 Single crystal substrate 7 Active layer 10 N electrode 14　Slope part

Claims (1)

[Claims] 1. An edge light emitting diode characterized in that the substrate has a stepped portion at the rear thereof, and a crystal growth layer is formed on the substrate.