Method for manufacturing light emitting diode

• US 8,168,455 B2
• Filed: 09/10/2009
• Issued: 05/01/2012
• Est. Priority Date: 02/20/2009
• Status: Expired due to Fees

• Current Assignee: National Central University
• Original Assignee: National Central University
• Inventors: Liu, Cheng-yi, Lin, Yung-Hsun
• Primary Examiner(s): Malsawma, Lex
• Application Number:
  US12/557,023
• Publication Number:
  US 20100216270A1
• Time in Patent Office: 964 Days
• Field of Search: 438/22, 438/47, 257/E33.001
• US Class Current: 438/22
• CPC Class Codes: H01L 33/08 with a plurality of light emitting regions, e.g. laterally discontinuous light emitting layer or photoluminescent region integrated within the semiconductor body H01L27/15 takes precedence
• CPC Class Codes: H01L 33/20 with a particular shape, e.g. curved or truncated substrate
• CPC Class Codes: H01L 33/42 Transparent materials
• CPC Class Codes: H01L 33/44 characterised by the coatings, e.g. passivation layer or anti-reflective coating

Abstract

A method for manufacturing light emitting diode (LED) is revealed. By means of wet etching, a plurality of pyramids is formed on epitaxial structure. The depth of the pyramids is beyond a n-type semiconductor layer, reaching a p-type semiconductor layer. Thus light emitting directions of the LED made by the method of the present invention are increased. Therefore, the light emitting efficiency of LED is improved.

Claims

1. A method for manufacturing light emitting diode comprising the steps of:

transferring an epitaxial structure to a transfer substrate and the epitaxial structure having a first semiconductor layer, a light emitting layer and a second semiconductor layer stacked on the transfer substrate in turn;

wet etching the epitaxial structure, through the second semiconductor layer to the first semiconductor layer and forming a plurality of pyramids on the epitaxial structure;

forming a protective layer on the plurality of pyramids on the epitaxial structure; and

forming a transparent electrode layer on the epitaxial structure and on the protective layer.

2. The method as claimed in claim 1, wherein electrical properties of the first semiconductor layer and the second semiconductor layer are opposite.

3. The method as claimed in claim 2, wherein the first semiconductor layer is a p-type semiconductor layer and the second semiconductor layer is a n-type semiconductor layer.

4. The method as claimed in claim 2, wherein the first semiconductor layer is a n-type semiconductor layer and the second semiconductor layer is a p-type semiconductor layer.

5. The method as claimed in claim 1, wherein the transfer substrate is made from silicon, copper, nickel, aluminum nitride or barium oxide.

6. The method as claimed in claim 1, wherein the first semiconductor layer is made from gallium nitride (GaN), aluminum gallium nitride (AlGaN), indium gallium nitride (InGaN), indium nitride (InN), gallium indium arsenic nitride (GaInAsN), gallium indium phosphide nitride (GaInPN), or one of nitrides of group III and group V.

7. The method as claimed in claim 1, wherein the second semiconductor layer is made from gallium nitride (GaN), aluminum gallium nitride (AlGaN), indium gallium nitride (InGaN), indium nitride (InN), gallium indium arsenic nitride (GaInAsN), gallium indium phosphide nitride (GaInPN), or one of nitrides of group III and group V.

8. The method as claimed in claim 1, wherein the light emitting layer is made from gallium nitride (GaN), aluminum gallium nitride (AlGaN), indium gallium nitride (InGaN), indium nitride (InN), gallium indium arsenic nitride (GaInAsN), gallium indium phosphide nitride (GaInPN), or one of nitrides of group III and group V.

9. The method as claimed in claim 1, wherein the step of wet etching the epitaxial structure further comprising the steps of:

heating an etchant to an etching temperature;

immersing the epitaxial structure disposed on the transfer substrate into the etchant for etching the epitaxial structural; and

taking out the epitaxial structure disposed on the transfer substrate after finishing etching.

10. The method as claimed in claim 9, wherein the etching temperature ranges from 100 to 200 degrees Celsius.

11. The method as claimed in claim 9, wherein a period in which the epitaxial structure disposed on the transfer substrate is immersed into the etchant ranges between 5 to 10 minutes.

12. The method as claimed in claim 9, wherein the etchant is selected from potassium hydroxide, sodium hydroxide and phosphoric acid.

13. The method as claimed in claim 1, wherein the protective layer is made from spin-on glass, silicon dioxide, aluminum nitride or silicon nitride.

14. The method as claimed in claim 1, wherein the transparent electrode layer is made from indium tin oxide, zinc oxide, aluminum-doped zinc oxide (AZO), or gallium-doped zinc oxide (GZO).

15. The method as claimed in claim 1, wherein the plurality of pyramids is continuous.

16. The method as claimed in claim 1, wherein the plurality of pyramids is discontinous.

17. The method as claimed in claim 1, wherein the plurality of pyramids is a periodic structure.

18. The method as claimed in claim 1, wherein the plurality of pyramids is an aperiodic structure.