EPITAXIAL SUBSTRATE, LIGHT-EMITTING DIODE, AND METHODS FOR MAKING THE EPITAXIAL SUBSTRATE AND THE LIGHT-EMITTING DIODE

• US 20120305942A1
• Filed: 02/27/2012
• Published: 12/06/2012
• Est. Priority Date: 05/31/2011
• Status: Abandoned Application

• Current Assignee: Aceplux Optotech Inc.
• Original Assignee: Aceplux Optotech Inc.
• Inventors: SHEI, Shih-Chang, LO, Hsin-Ming
• Application Number:
  US13/406,023
• Publication Number:
  US 20120305942A1
• Time in Patent Office: Days
• US Class Current: 257/77
• CPC Class Codes: H01L 33/007 comprising nitride compounds
• CPC Class Codes: H01L 33/12 with a stress relaxation structure, e.g. buffer layer
• CPC Class Codes: H01L 33/58 Optical field-shaping elements

Abstract

An epitaxial substrate includes: a base member; and a plurality of spaced apart light-transmissive members, each of which is formed on and tapers from an upper surface of the base member, and each of which is made of a light-transmissive material having a refractive index lower than that of the base member. A light-emitting diode having the epitaxial substrate, and methods for making the epitaxial substrate and the light-emitting diode are also disclosed.

Claims

1. An epitaxial substrate, comprising:

a base member; and

a plurality of spaced apart light-transmissive members, each of which is formed on and tapers from an upper surface of said base member, and each of which is made of a light-transmissive material having a refractive index lower than that of said base member.

2. The epitaxial substrate of claim 1, wherein each of said light-transmissive members is in a cone-shape, and has a bottom face that contacts said upper surface of said base member and that has a maximum width, and a height from said bottom face, a ratio of said height to said maximum width being not less than 0.25.

3. The epitaxial substrate of claim 1, wherein said light-transmissive members are spaced apart from one another by a distance not greater than 1 μ

m.

4. The epitaxial substrate of claim 1, wherein said light-transmissive material has a heat resistivity of not less than 1000°

C.

5. The epitaxial substrate of claim 1, wherein said light-transmissive material is selected from the group consisting of silicon oxide, silicon oxynitride, and magnesium fluoride.

6. The epitaxial substrate of claim 1, wherein said base member is made from a material selected from the group consisting of aluminum oxide, silicon carbide, silicon, and aluminum nitride.

7. A method for making an epitaxial substrate, comprising:

(a) forming over a base member a light-transmissive layer that is made of a light-transmissive material having a refractive index lower than that of the base member;

(b) forming a patterned mask over the light-transmissive layer;

(c) heat-treating the patterned mask at a temperature not higher than a glass transition temperature of the patterned mask;

(d) performing a dry-etching treatment on the light-transmissive layer and the patterned mask that is heat-treated, so that the light-transmissive layer is formed into a plurality of spaced apart light-transmissive members; and

(e) removing the patterned mask from the light-transmissive members.

8. The method of claim 7, wherein each of the light-transmissive members is in a cone-shape, and has a bottom face that contacts an upper surface of said base member and that has a maximum width, and a height from the bottom face, a ratio of the height to the maximum width being not less than 0.25, the light-transmissive members being spaced apart from one another by a distance not greater than 1 μ

m.

9. The method of claim 7, wherein the light-transmissive material has a heat resistivity of not less than 1000°

C.

10. The method of claim 7, wherein the light-transmissive material is selected from the group consisting of silicon oxide, silicon oxynitride, and magnesium fluoride.

11. The method of claim 7, wherein the base member is made from a material selected from the group consisting of aluminum oxide, silicon carbide, silicon, and aluminum nitride.

12. A light-emitting diode, comprising:

an epitaxial substrate including a base member, and a plurality of spaced apart light-transmissive members, each of which is formed on and tapers from an upper surface of said base member, and each of which is made of a light-transmissive material having a refractive index lower than that of said base member; and

a light-emitting unit formed on said epitaxial substrate to cover said light-transmissive members.

13. The light-emitting diode of claim 12, wherein each of said light-transmissive members is in a cone-shape, and has a bottom face that contacts said upper surface of said base member and that has a maximum width, and a height from the bottom face, a ratio of the height to the maximum width being not less than 0.25, said light-transmissive members being spaced apart from one another by a distance not greater than 1 μ

m.

14. The light-emitting diode of claim 12, wherein said light-emitting unit and said light-transmissive members cooperatively define at least one cavity therebetween.

15. The light-emitting diode of claim 12, wherein said base member is made from a material selected from the group consisting of aluminum oxide, silicon carbide, silicon, and aluminum nitride.

16. The light-emitting diode of claim 12, wherein said light-transmissive material is selected from the group consisting of silicon oxide, silicon oxynitride, and magnesium fluoride.

17. A method for making a light-emitting diode, comprising:

(a) forming over a base member a light-transmissive layer that is made of a light-transmissive material having a refractive index lower than that of the base member;

(b) forming a patterned mask over the light-transmissive Layer;

(c) heat-treating the patterned mask at a temperature not higher than a glass transition temperature of the patterned mask;

(d) performing a dry-etching treatment on the light-transmissive layer and the patterned mask that is heat-treated, so that the light-transmissive layer is formed into a plurality of spaced apart light-transmissive members, followed by removing the patterned mask from the light-transmissive members; and

(e) forming a light-emitting unit over the light-transmissive members.

18. The method claim 17, wherein each of the light-transmissive members is in a cone-shape, and has a bottom face that contacts an upper surface of said base member and that has a maximum width, and a height from the bottom face, a ratio of the height to the maximum width being not less than 0.25, the light-transmissive members being spaced apart from one another by a distance not greater than 1 μ

m.

19. The method of claim 17, wherein the step (e) includes:

laterally and epitaxially growing a first-type semiconductor layer over the light-transmissive members, the first-type semiconductor layer and the light-transmissive members cooperatively defining at least one cavity therebetween.

20. The method of claim 17, wherein the base member is made from a material selected from the group consisting of aluminum oxide, silicon carbide, silicon, and aluminum nitride.

21. The method of claim 17, wherein the light-transmissive material is selected from the group consisting of silicon oxide, silicon oxynitride, and magnesium fluoride.