LIGHT EMITTING DEVICE WITH PLANAR CURRENT BLOCK STRUCTURE
A light-emitting device comprises a support base having a planar surface, a semiconductor stacked structure disposed on the planar surface, the semiconductor stacked structure comprising a first semiconductor layer, an active layer, a second semiconductor layer, a current block region formed in one of the first semiconductor layer and the second semiconductor layer and physically contacts the planar surface and an electrode disposed on the semiconductor stacked structure.
Latest EPISTAR CORPORATION Patents:
The present application relates to a light-emitting device with a current block region, and a method to manufacture the same.
DESCRIPTION OF BACKGROUND ARTIn recent years, as the applications of the light-emitting diode increasing, many methods for increasing the light extraction efficiency have been provided. One of the methods is to reduce the electrical current crowding and make the electrical current spread between the electrodes wide. If the electrical current between the electrodes is not uniform and causes the electrical current crowded in some regions, the total light efficiency of the light-emitting diode will decrease.
In recent years, many methods have been provided to improve the light extraction efficiency of the light-emitting diode as the light-emitting diode is applied more widely. However, the current spreading in the light-emitting diode is not uniform so the current distribution is crowded in some areas, and there is a need to improve the light extraction efficiency
In order to make the current spreading uniform, a conventional LED structure has a current block region of low electric conductivity in the p-AlGaAs window layer to improve the current spreading and increase the light-emitting efficiency.
Referring to
A light-emitting device comprises a support base having a planar surface, a semiconductor stacked structure disposed on the planar surface, the semiconductor stacked structure comprising a first semiconductor layer, an active layer, a second semiconductor layer, a current block region formed in one of the first semiconductor layer and the second semiconductor layer and physically contacts the planar surface and an electrode disposed on the semiconductor stacked structure.
A light-emitting device comprises a support base, a plurality of light-emitting units on the support base and a conductive unit electrically connecting the plurality of light-emitting units, wherein each of the plurality of light-emitting unit comprises a semiconductor stacked structure, an electrode disposed on the semiconductor stacked structure, a reflective layer connecting the semiconductor stacked structure, and a current block region in the semiconductor stacked structure, and wherein the reflective layer has a planar surface, and the current block region contacts the planar surface, and wherein the electrode is aligned with the current block region.
A method of manufacturing a light-emitting device comprises the steps of providing a growth substrate, growing a semiconductor stacked structure on the growth substrate, wherein the semiconductor stacked structure comprises an active layer, a first semiconductor layer on the active layer, and a second semiconductor layer under the active layer, defining an alignment mark on the second semiconductor layer, forming a current block region in the semiconductor stacked structure by oxygen plasma treatment, N2O plasma treatment, argon plasma treatment, ion implantation, or wet oxidation, forming a reflective layer on the second semiconductor layer, bonding a substrate to the reflective layer, removing the growing substrate to expose the first semiconductor layer, and forming an electrode on the first semiconductor layer, wherein the electrode is aligned to the current block region by the alignment marks.
Exemplary embodiments of the present application will be described in detail with reference to the accompanying drawings hereafter. The following embodiments are given by way of illustration to help those skilled in the art fully understand the spirit of the present application. Hence, it should be noted that the present application is not limited to the embodiments herein and can be realized by various forms. Further, the drawings are not precise scale and components may be exaggerated in view of width, height, length, etc. Herein, the similar or identical reference numerals will denote the similar or identical components throughout the drawings.
Each of the plurality of the current block regions 20 is formed in the semiconductor stacked layer 12 and directly contacts with the reflector layer 14. The first contact surface 100 between the reflector layer 14 and the current block regions 20 and the second contact surface 101 between the reflector layer 14 and the semiconductor stacked layer 12 are coplanar. Each of the current block regions 20 can be formed by ion implantation, oxygen plasma treatment, N2O plasma treatment, argon plasma treatment, or wet oxidation. The material of the current block regions can have an electric conductivity less than one-tenth of the electric conductivity of the semiconductor material of the semiconductor stacked layer 12 around the current block regions 20, or be an insulated oxide, such as SiO2, TiO2, or SiNx. While the electrical current disperses through the second contact surface 101, the high electrical field does not happen and the light-emitting diode does not fail.
Each of the current block regions 20 corresponds to each of the upper electrodes 2 respectively and the thickness of each of the current block regions 20 is greater than 50 Å. In other words, a virtual central normal line 102 of each of the upper electrodes 2 extends to pass the corresponding current block region 20. The width 104 of each of the current block regions 20 is greater than the width 106 of the corresponding upper electrode 2 to make the electric current spreading wilder between the upper electrodes 2 and the lower electrode 4.
Further, the aforementioned vertical type light-emitting diodes can be connected in series to form a high voltage light-emitting device.
Between any two light-emitting diodes 40A, the first insulation layer 30A and the second insulation layer 30B cover the first side wall 50A, the second side wall 52A respectively and a portion of the upper surface 54. For each of the light-emitting diode 40A, the reflector layer 14A protrudes from the first side wall 50 and is uncover by the first insulation layer 30A. For any two light-emitting diodes 40, a bridge metal 32A, which is disposed between the two light-emitting diodes 40A, connects the reflector layer 14A of one of the two light-emitting diodes 40A with the upper electrode 2 of the other light-emitting diode 40A. For any two electrically connected light-emitting diodes 40A, the bridge metal 32A is isolated from each of the semiconductor stacked layers 12 and each of the reflector layers 14A by the first insulation layer 30A and the second insulation layer 30B.
The light-emitting device or light-emitted diode mentioned above may be mounted with the substrate onto a submount via a solder bump or a glue material to form a light-emitting apparatus. Besides, the submount further comprises one circuit layout electrically connected to the electrode of the light-emitting device via an electrical conductive structure, such as a metal wire.
Claims
1. A light-emitting device, comprising:
- a support base having a planar surface;
- a semiconductor stacked structure disposed on the planar surface, the semiconductor stacked structure comprising a first semiconductor layer, an active layer, a second semiconductor layer;
- a current block region formed in one of the first semiconductor layer and the second semiconductor layer and physically contacts the planar surface; and
- an electrode disposed on the semiconductor stacked structure.
2. A light-emitting device according to claim 1, further comprising a plurality of the current block regions and a plurality of the electrodes, wherein each current block region corresponds to one of the electrode.
3. A light-emitting device according to claim 1, wherein a width of the current block region is greater than a width of the electrode, and/or the shape of the current block region is the same as the shape the electrode.
4. A light-emitting device according to claim 3, wherein the width of the at least one current block region is 5 times greater than the width of the electrode.
5. A light-emitting device according to claim 1, wherein the current block region comprises a transparent and a low electrically conductive dielectric material.
6. A light-emitting device according to claim 1, wherein the electrical conductivity of the current block region is less than one-tenth of the electrical conductivity of the semiconductor stacked structure.
7. A light-emitting device according to claim 1, further comprising a transparent conductive layer between the semiconductor stacked structure and the electrode.
8. A light-emitting device according to claim 1, wherein the support base comprises a reflective layer, a bonding layer, and a substrate.
9. A light-emitting device according to claim 8, wherein the reflective layer comprises an electrically conductive and reflective material.
10. A light-emitting device according to claim 8, wherein the bonding layer and the substrate are electrically conductive.
11. A light-emitting device, comprising:
- a support base;
- a plurality of light-emitting units on the support base; and
- a conductive unit electrically connecting the plurality of light-emitting units, wherein each of the plurality of light-emitting unit comprises a semiconductor stacked structure, an electrode disposed on the semiconductor stacked structure, a reflective layer connecting the semiconductor stacked structure, and a current block region in the semiconductor stacked structure,
- wherein the reflective layer has a planar surface, and the current block region contacts the planar surface,
- wherein the electrode is aligned with the current block region.
12. A light-emitting device according to claim 11, wherein a width of the current block region is greater than a width of the electrode, and/or the shape of the current block region is the same as the shape of the electrode.
13. A light-emitting device according to claim 12, wherein the width of the at least one current block region is 5 times greater than the width of the electrode.
14. A light-emitting device according to claim 11, wherein the current block region comprises a transparent and a low electrically conductive dielectric material.
15. A light-emitting device according to claim 11, wherein the electrical conductivity of the current block region is less than one-tenth of the electrical conductivity of the semiconductor stacked structure.
16. A light-emitting device according to claim 11, further comprising a transparent conductive layer between the semiconductor stacked structure and the electrode.
17. A light-emitting device according to claim 11, wherein the reflective layer comprises an electrically conductive and reflective material.
18. A light-emitting device according to claim 11, wherein the support base comprises a bonding layer, and a substrate.
19. A light-emitting device according to claim 18, wherein the bonding layer is electrically conductive or electrically insulating.
20. A method of manufacturing a light-emitting device comprising the steps of:
- providing a growth substrate;
- growing a semiconductor stacked structure on the growth substrate, wherein the semiconductor stacked structure comprises an active layer, a first semiconductor layer on the active layer, and a second semiconductor layer under the active layer;
- defining an alignment mark on the second semiconductor layer;
- forming a current block region in the semiconductor stacked structure by oxygen plasma treatment, N2O plasma treatment, argon plasma treatment, ion implantation, or wet oxidation;
- forming a reflective layer on the second semiconductor layer;
- bonding a substrate to the reflective layer;
- removing the growing substrate to expose the first semiconductor layer; and
- forming an electrode on the first semiconductor layer,
- wherein the electrode is aligned to the current block region by the alignment marks.
Type: Application
Filed: Feb 17, 2012
Publication Date: Aug 22, 2013
Applicant: EPISTAR CORPORATION (Hsinchu)
Inventor: Tsung-Hsien YANG (Hsinchu)
Application Number: 13/399,381
International Classification: H01L 33/60 (20100101); H01L 33/08 (20100101);