Light emitting diode and manufacturing method therefor

Abstract

A light emitting diode is composed of a p-type GaP substrate 12 and layers laminated on the p-type GaP substrate 12, including a p-type GaP contact layer 13, a p-type AlInP second cladding layer 14, a p-type AlGaInP active layer 15, an n-type AlInP first cladding layer 16 and an n-type AlGaAs current diffusion layer 17. The entire lateral surfaces of the p-type GaP substrate 12 are processed into a roughened state by a dicing blade. The light emitting diode has high light intensity and its surface can be roughened under any circumstances regardless of its material and orientation so that characteristic failures can be prevented from occurring.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus are not intended to limit the present invention, and wherein:

FIG. 1 is a schematic view showing the configuration of a light emitting diode in a first embodiment of the present invention;

FIG. 2A is a schematic view for explaining MOCVD crystal growth of the light emitting diode shown in FIG. 1;

FIG. 2B is a schematic view for explaining formation of GaP junction structure in the light emitting diode shown in FIG. 1;

FIG. 3A is a view showing the grinded surface state of a p-type GaP substrate diced by a dicing blade having an abrasive grain size of 4 μm;

FIG. 3B is a view showing the grinded surface state of a p-type GaP substrate diced by a dicing blade having an abrasive grain size of 1 μm;

FIG. 4A is an image view showing optical paths inside a light emitting diode having mirror-polished lateral surfaces;

FIG. 4B is an image view showing optical paths inside a light emitting diode having roughened lateral surfaces;

FIG. 5A is a graph view showing an orientation characteristic of the light emitting diode having roughened lateral surfaces;

FIG. 5B is a graph view showing an orientation characteristic of the light emitting diode having mirror-polished lateral surfaces;

FIG. 6 is a graph view showing difference in output of a light emitting diode caused by difference in abrasive grain size of a blade;

FIG. 7 is a schematic view showing the configuration of a conventional light emitting diode;

FIG. 8 is a schematic view showing the configuration of a light emitting diode in a second embodiment of the present invention;

FIG. 9A is a schematic view for explaining MOCVD crystal growth of the light emitting diode shown in FIG. 8;

FIG. 9B is a schematic view for explaining formation of GaP junction structure in the light emitting diode shown in FIG. 8;

FIG. 10A is a view showing the grinded surface state of a p-type GaP substrate diced by a dicing blade having an abrasive grain size of 4 μm;

FIG. 10B is a view showing the grinded surface state of a p-type GaP substrate diced by a dicing blade having an abrasive grain size of 1 μm;

FIG. 11A is an image view showing optical paths inside a light emitting diode having a mirror-polished top surface;

FIG. 11B is an image view showing optical paths inside a light emitting diode having a mirror-polished top surface;

FIG. 12 is a graph view showing difference in output of a light emitting diode caused by difference in abrasive grain size of a blade;

FIG. 13 is a schematic view showing one aspect in the case where a part of the top surface is diced; and

FIG. 14 is a schematic view showing the configuration of an another conventional light emitting diode.

Claims

1. A light emitting diode, comprising: an emitter layer made of a semiconductor layer;an intermediate layer made of a semiconductor layer placed on the emitter layer; anda transparent layer having transparency to outgoing light from the emitter layer and placed on the intermediate layer,wherein a part of or an entire surface of the transparent layer is processed into a roughened state by a dicing blade.

2. The light emitting diode according to claim 1, wherein the surface processed into a roughened state by the dicing blade is lateral surfaces of the transparent layer.

3. The light emitting diode according to claim 1, wherein the surface processed into a roughened state by the dicing blade is a top surface of the transparent layer.

4. The light emitting diode according to claim 1, wherein a part of or entire lateral surfaces of the emitter layer is processed into a roughened state by the dicing blade.

5. The light emitting diode according to claim 1, wherein the transparent layer is a substrate glued to the intermediate layer.

6. The light emitting diode according to claim 1, wherein the transparent layer is an epitaxial growth layer or a substrate for epitaxial growth use.

7. The light emitting diode according to claim 1, wherein the emitter layer is made of a compound containing at least two or more elements out of Al, Ga, As, In, P, Zn, Se, Te, Sn, Si, C, Ti, Mg, Cd, B, N, O and S.

8. The light emitting diode according to claim 1, wherein the transparent layer is made of a compound containing at least two or more elements out of Al, Ga, As, In, P, Zn, Se, Te, Sn, Si, C, Ti, Mg, Cd, B, N, O and S.

9. The light emitting diode according to claim 1, wherein the emitter layer is made of AlGaInP, andwherein the transparent layer is made of GaP.

10. A manufacturing method for a light emitting diode, comprising the steps for: manufacturing a wafer including an emitter layer made of a semiconductor layer, an intermediate layer made of a semiconductor layer placed on the emitter layer, and a transparent layer having transparency to outgoing light from the emitter layer and placed on the intermediate layer; andprocessing a part of or an entire surface of the transparent layer into a roughened state by a dicing blade.

11. The manufacturing method for a light emitting diode according to claim 10, wherein the surface processed into a roughened state by a dicing blade is lateral surfaces of the transparent layer.

12. The manufacturing method for a light emitting diode according to claim 10, wherein the surface processed into a roughened state by a dicing blade is top surfaces of the transparent layer.

13. The manufacturing method for a light emitting diode according to claim 11, wherein before the wafer is diced into a form of devices, a part of or entire lateral surfaces of the transparent layer are roughened through half dicing or pre-dicing by the dicing blade.

14. The manufacturing method for a light emitting diode according to claim 11, wherein after the wafer is diced into a form of devices, a part of or entire surfaces of the transparent layer are processed into a roughened state by the dicing blade.

15. The manufacturing method for a light emitting diode according to claim 10, wherein a size of an abrasive grain of the dicing blade is 2 μm or more.