Omnidirectional reflector

• US 8,609,448 B2
• Filed: 04/05/2013
• Issued: 12/17/2013
• Est. Priority Date: 08/18/2008
• Status: Active Grant

• Current Assignee: Epistar Corporation
• Original Assignee: TSMC Solid State Lighting Ltd. (Epistar Corporation)
• Inventors: Chen, Ding-Yuan, Yu, Chen-Hua, Chiou, Wen-Chih
• Primary Examiner(s): Stark, Jarrett
• Assistant Examiner(s): TYNES JR., LAWRENCE C
• Application Number:
  US13/857,678
• Publication Number:
  US 20130224892A1
• Time in Patent Office: 256 Days
• Field of Search: 257/98, 257/603
• US Class Current: 438/29
• CPC Class Codes: H01L 2933/0083 Periodic patterns for optical field-shaping in or on the semiconductor body or semiconductor body package, e.g. photonic bandgap structures
• CPC Class Codes: H01L 33/0093 Wafer bonding; Removal of the growth substrate
• CPC Class Codes: H01L 33/10 with a light reflecting structure, e.g. semiconductor Bragg reflector
• CPC Class Codes: H01L 33/46 Reflective coating, e.g. dielectric Bragg reflector
• CPC Class Codes: H01L 33/60 Reflective elements

Abstract

A system and method for manufacturing an LED is provided. A preferred embodiment includes a substrate with a distributed Bragg reflector formed over the substrate. A photonic crystal layer is formed over the distributed Bragg reflector to collimate the light that impinges upon the distributed Bragg reflector, thereby increasing the efficiency of the distributed Bragg reflector. A first contact layer, an active layer, and a second contact layer are preferably either formed over the photonic crystal layer or alternatively attached to the photonic crystal layer.

Claims

1. A method, comprising:

forming a reflective layer over a substrate through a deposition process or an epitaxy process;

forming a photonic crystal layer over the substrate, the forming of the photonic crystal layer further comprising;

depositing a base material over the substrate and forming a lattice of dielectric material in the base material, wherein the lattice of dielectric material is formed so that the photonic crystal layer is homogenous with respect to a first direction and non-homogenous with respect to a second direction and a third direction; and

forming a light-emitting diode over the photonic crystal layer or the reflective layer through a plurality of epitaxial growth processes.

2. The method of claim 1, wherein the reflective layer is formed over the photonic crystal layer.

3. The method of claim 1, wherein the photonic crystal layer is formed over the reflective layer.

4. The method of claim 1, wherein the forming of the reflective layer comprises forming a stack of alternating materials with alternating high and low refractive indices.

5. The method of claim 1, wherein the forming of the photonic crystal layer is performed such that the first direction is perpendicular to the second and third directions.

6. The method of claim 1, wherein the depositing of the base material comprises depositing GaN, AlGaN, or Si as the base material.

7. The method of claim 6, wherein the depositing of the base material is performed so that the base material has a thickness in a range from about 10 nanometers to about 5000 nanometers.

8. The method of claim 1, wherein the forming of the lattice of dielectric material comprises:

forming a lattice of openings in a repeating pattern through the base material; and

filling the lattice of openings with one of;

air, silicon dioxide, titanium dioxide, GaN, or AlGaN.

9. The method of claim 8, wherein the forming of the lattice of openings is performed so that the lattice of openings have a pitch in a range from about 10 nanometers to about 1000 nanometers.

10. A method, comprising:

forming a reflective layer over a substrate through a deposition process or an epitaxy process;

forming a photonic crystal layer over the substrate, the forming of the photonic crystal layer further comprising;

depositing a base material over the substrate and forming a lattice of dielectric material in the base material, wherein the lattice of dielectric material is formed so that the photonic crystal layer is homogenous with respect to a first direction and non-homogenous with respect to a second direction and a third direction; and

bonding a light-emitting diode to the photonic crystal layer or the reflective layer.

11. The method of claim 10, wherein the reflective layer is formed over the photonic crystal layer.

12. The method of claim 10, wherein the photonic crystal layer is formed over the reflective layer.

13. The method of claim 10, wherein the forming of the reflective layer comprises forming a stack of alternating materials with alternating high and low refractive indices.

14. The method of claim 10, wherein the forming of the photonic crystal layer is performed such that the first direction is perpendicular to the second and third directions.

15. The method of claim 10, wherein the depositing of the base material comprises depositing GaN, AlGaN, or Si as the base material.

16. The method of claim 15, wherein the depositing of the base material is performed so that the base material has a thickness in a range from about 10 nanometers to about 5000 nanometers.

17. The method of claim 10, wherein the forming of the lattice of dielectric material comprises:

forming a lattice of openings in a repeating pattern through the base material; and

filling the lattice of openings with one of;

air, silicon dioxide, titanium dioxide, GaN, or AlGaN.

18. The method of claim 17, wherein the forming of the lattice of openings is performed so that the lattice of openings have a pitch in a range from about 10 nanometers to about 1000 nanometers.

19. A method, comprising:

forming a reflective layer over a substrate through a deposition process or an epitaxy process;

forming a photonic crystal layer over the substrate, the forming of the photonic crystal layer further comprising;

depositing a base material over the substrate and forming a lattice of dielectric material in the base material, wherein the lattice of dielectric material is formed so that the photonic crystal layer is homogenous with respect to a first direction and non-homogenous with respect to a second direction and a third direction; and

performing one of the following steps;

forming a light-emitting diode over the photonic crystal layer or the reflective layer through a plurality of epitaxial growth processes; and

bonding a light-emitting diode to the photonic crystal layer or the reflective layer.

20. The method of claim 19, wherein:

the forming of the reflective layer comprises forming a stack of alternating materials with alternating high and low refractive indices;

the depositing of the base material comprises depositing GaN, AlGaN, or Si as the base material; and

the forming of the lattice of dielectric material comprises;

forming a lattice of openings in a repeating pattern through the base material; and

filling the lattice of openings with one of;

air, silicon dioxide, titanium dioxide, GaN, or AlGaN.