EP-4742864-A1 - FLIP CHIP LIGHT EMITTING DIODE

EP4742864A1EP 4742864 A1EP4742864 A1EP 4742864A1EP-4742864-A1

Abstract

The present invention provides a flip-chip light-emitting diode, comprising a substrate, a light-emitting structure, a P-type electrode structure, and an N-type electrode structure. The light-emitting structure is disposed on the substrate and includes a gallium phosphide layer and a semiconductor epitaxy structure, with the gallium phosphide layer positioned between the substrate and the semiconductor epitaxy structure. The semiconductor epitaxy structure has, in sequence, a P-type current diffusing layer, a light-emitting layer, an N-type semiconductor layer, and a transparent ohmic contact layer. The P-type electrode structure is disposed on the gallium phosphide layer of the light-emitting structure, and the N-type electrode structure is disposed on the transparent ohmic contact layer. The N-type semiconductor layer has a distributed Bragg reflector, which is positioned between the light-emitting layer and the N-type electrode structure.

Inventors

LIN, KUN-LI
HSIAO, YU-TONG
CHEN, HUANG-MING

Assignees

Taiwan-Asia Semiconductor Corporation

Dates

Publication Date: 20260513
Application Date: 20250723

Claims (10)

A flip-chip light-emitting diode, comprising: a substrate; a light-emitting structure, disposed on the substrate and including a gallium phosphide layer and a semiconductor epitaxy structure, wherein the gallium phosphide layer is positioned between the substrate and the semiconductor epitaxy structure, the semiconductor epitaxy structure has a P-type current diffusing layer, a light-emitting layer, an N-type semiconductor layer, and a transparent ohmic contact layer, the P-type current diffusing layer is disposed on the gallium phosphide layer, the light-emitting layer is disposed on the P-type current diffusing layer, the N-type semiconductor layer is disposed on the light-emitting layer, and the transparent ohmic contact layer is disposed on the N-type semiconductor layer; a P-type electrode structure, disposed on the gallium phosphide layer of the light-emitting structure; and an N-type electrode structure, disposed on the transparent ohmic contact layer; wherein the N-type semiconductor layer has a distributed Bragg reflector, and the distributed Bragg reflector is located between the light-emitting layer and the N-type electrode structure.
The flip-chip light-emitting diode as claimed in claim 1, wherein the N-type electrode structure includes a current confinement layer and a metal reflection layer, the current confinement layer is disposed on the transparent ohmic contact layer and has a plurality of openings, and the metal reflection layer covers the current confinement layer to form an omni-directional reflector in conjunction with the current confinement layer; and wherein the metal reflection layer forms a plurality of dot ohmic contact structures with the transparent ohmic contact layer through the plurality of openings.
The flip-chip light-emitting diode as claimed in claim 2, wherein the current confinement layer is made of a non-conductive material.
The flip-chip light-emitting diode as claimed in any of the previous claims, wherein a resistance of the P-type current diffusing layer is lower than a resistance of the N-type semiconductor layer.
The flip-chip light-emitting diode as claimed in any of the previous claims, wherein the P-type current diffusing layer is an aluminum gallium arsenide layer with a doping concentration exceeding 1E+19 atoms/cm 3 .
The flip-chip light-emitting diode as claimed in any of the previous claims, wherein the transparent ohmic contact layer is made of a material that does not absorb light emitted by the light-emitting layer within a corresponding emission wavelength band thereof.
The flip-chip light-emitting diode as claimed in any of the previous claims, wherein the P-type electrode structure includes a finger electrode portion and a pad portion, the finger electrode portion respectively contacts with the gallium phosphide layer of the light-emitting structure and with the pad portion, and the finger electrode portion is positioned in a periphery of the semiconductor epitaxy structure and symmetrically arranged with respect to a center of the semiconductor epitaxy structure.
The flip-chip light-emitting diode as claimed in claim 7, wherein the finger electrode portion is a frame electrode, and the N-type electrode structure is either a plurality of regularly arranged dot electrodes or another frame electrode.
The flip-chip light-emitting diode as claimed in claim 7, wherein the finger electrode portion is a set of parallel line electrodes, and the N-type electrode structure is either a plurality of regularly arranged dot electrodes or another set of parallel line electrodes that are parallel to the finger electrode portion.
The flip-chip light-emitting diode as claimed in any of the previous claims, wherein the N-type electrode structure is a plurality of dot ohmic contact structures disposed on the transparent ohmic contact layer, and each of the dot ohmic contact structures forms an ohmic contact with the transparent ohmic contact layer.

Description

CROSS REFERENCE TO RELATED APPLICATION This application claims the benefit of Taiwan Patent Application Serial No. 113143310 filed on November 12, 2024. The entirety of the Application is incorporated herein by reference. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light-emitting diode, and more particularly, to a flip-chip light-emitting diode with decreased shadow regions generated by electrodes. 2. Description of Related Art For conventional light-emitting diodes, in structural design, electrodes are disposed above light-emitting regions. As a result, under near-field optics, shadow regions occur corresponding to positions of the electrodes, which in turn affects light-emitting performances of the light-emitting diodes. While conventional flip-chip light-emitting diodes adopt different structural designs from the conventional light-emitting diodes, by disposing electrodes below the light-emitting regions, instead of above the light-emitting regions, to avoid forming the aforementioned shadow regions. However, for the conventional flip-chip light-emitting diodes, due to differences in materials used for the electrodes and other structural components, variations in reflectivity appear, which will still induce other shadow regions under near-field optics, even though the electrodes are disposed below the light-emitting regions, and similarly affects light-emitting performances of the flip-chip light-emitting diodes. Furthermore, if current distributing of the flip-chip light-emitting diodes is uneven, the shadow regions formed by the electrodes will become more obvious. In light of this, it is really worthy of research and development to design a flip-chip light-emitting diode for solving those above-mentioned problems. SUMMARY OF THE INVENTION An objective of the present invention is to provide a flip-chip light-emitting diode with decreased shadow regions generated by electrodes. To achieve the above objective, the flip-chip light-emitting diode of the present invention comprises a substrate, a light-emitting structure, a P-type electrode structure, and an N-type electrode structure. The light-emitting structure is disposed on the substrate and includes a gallium phosphide layer and a semiconductor epitaxy structure, wherein the gallium phosphide layer is positioned between the substrate and the semiconductor epitaxy structure. The semiconductor epitaxy structure has a P-type current diffusing layer, a light-emitting layer, an N-type semiconductor layer, and a transparent ohmic contact layer, wherein the P-type current diffusing layer is disposed on the gallium phosphide layer, the light-emitting layer is disposed on the P-type current diffusing layer, the N-type semiconductor layer is disposed on the light-emitting layer, and the transparent ohmic contact layer is disposed on the N-type semiconductor layer. The P-type electrode structure is disposed on the gallium phosphide layer of the light-emitting structure, and the N-type electrode structure is disposed on the transparent ohmic contact layer. The N-type semiconductor layer has a distributed Bragg reflector, and the distributed Bragg reflector is located between the light-emitting layer and the N-type electrode structure. In one embodiment of the present invention, the N-type electrode structure includes a current confinement layer and a metal reflection layer. The current confinement layer is disposed on the transparent ohmic contact layer and has a plurality of openings, and the metal reflection layer covers the current confinement layer to form an omni-directional reflector in conjunction with the current confinement layer. And the metal reflection layer forms a plurality of dot ohmic contact structures with the transparent ohmic contact layer through the plurality of openings. In one embodiment of the present invention, the current confinement layer is made of a non-conductive material. In one embodiment of the present invention, a resistance of the P-type current diffusing layer is lower than a resistance of the N-type semiconductor layer. In one embodiment of the present invention, the P-type current diffusing layer is an aluminum gallium arsenide layer with a doping concentration exceeding 1E+19 atoms/cm3. In one embodiment of the present invention, the transparent ohmic contact layer is made of a material that does not absorb light emitted by the light-emitting layer within a corresponding emission wavelength band thereof. In one embodiment of the present invention, the P-type electrode structure includes a finger electrode portion and a pad portion. The finger electrode portion respectively contacts with the gallium phosphide layer of the light-emitting structure and with the pad portion, and the finger electrode portion is positioned in a periphery of the semiconductor epitaxy structure and symmetrically arranged with respect to a center of the semiconductor epitaxy structure. In one embodiment o