LIGHT EMITTING DIODES (LEDs) WITH IMPROVED LIGHT EXTRACTION BY ROUGHENING

• US 20080293171A1
• Filed: 01/23/2008
• Published: 11/27/2008
• Est. Priority Date: 01/11/2005
• Status: Active Grant

• Current Assignee: Chuong Anh Tran, Trung Tri Doan
• Original Assignee: Chuong Anh Tran, Trung Tri Doan
• Inventors: Tran, Chuong Anh, Doan, Trung Tri
• Granted Patent: US 7,629,195 B2
• Time in Patent Office: Days
• US Class Current: 438/22
• CPC Class Codes: H01L 33/0095 Post-treatment of devices, e.g. annealing, recrystallisation or short-circuit elimination
• CPC Class Codes: H01L 33/22 Roughened surfaces, e.g. at the interface between epitaxial layers

Abstract

Systems and methods are disclosed for fabricating a semiconductor light emitting diode (LED) device by forming an n-gallium nitride (n-GaN) layer on the LED device and roughening the surface of the n-GaN layer to extract light from an interior of the LED device.

Claims

1. A method of fabricating a light-emitting diode (LED) device having a roughened surface for scattering light, the method comprising:

depositing an n-doped layer above a carrier substrate;

depositing an active layer for emitting light above the n-doped layer;

depositing a p-doped layer above the active layer;

forming a conductive substrate above the p-doped layer;

removing the carrier substrate to expose the n-doped layer;

immersing a surface of the n-doped layer in an electrolytic solution;

applying an electrical bias to the conductive substrate; and

illuminating the surface of the n-doped layer such that photo-electrochemical (PEC) oxidation and etching occurs to form the roughened surface of the LED device on the n-doped layer.

2. The method of claim 1, further comprising forming a conductive contact on the n-doped layer, wherein the conductive contact acts as a mask during the PEC oxidation and etching.

3. The method of claim 1, wherein the electrolytic solution can be a combination of an oxidizing agent and either an acid or an alkaline solution.

4. The method of claim 2, wherein the oxidizing agent comprises at least one of H₂O₂ and K₂S₂O₈.

5. The method of claim 2, wherein the acid solution comprises at least one of H₂SO₄, HF, HCl, H₃PO₄, HNO₃, and CH₃COOH.

6. The method of claim 2, wherein the alkaline solution comprises one or the mixture of KOH, NaOH, and NH₄OH.

7. The method of claim 1, wherein the electrical bias ranges from −

10 V to +10 V.