Light-emitting diode with enhanced brightness and method for fabricating the same

• US 6,716,654 B2
• Filed: 03/12/2002
• Issued: 04/06/2004
• Est. Priority Date: 03/12/2002
• Status: Active Grant

• Current Assignee: Opto Tech Corporation (OptoTech Corp.)
• Original Assignee: Opto Tech Corporation (OptoTech Corp.)
• Inventors: Lin, San Bao, Wang, Kwang-Ru, Lu, Hung-Yuan, Hwang, Yung-Chiang, Yu, Hsueh-Chih, Chu, Yen-Hu, Chang, Chui-Chuan, Hsu, Chia-Liang, Tsai, Chang-Da, Lin, Ming-Der, Hsu, Jung-Kuei
• Primary Examiner(s): Pham, Long
• Assistant Examiner(s): LOUIE, WAI SING
• Application Number:
  US10/095,003
• Publication Number:
  US 20030173602A1
• Time in Patent Office: 756 Days
• Field of Search: 438/22, 438/24, 438/29, 438/36, 438/37, 438/39, 438/42, 438/44, 438/46, 438/47, 257/79-105
• US Class Current: 438/22
• CPC Class Codes: H01L 21/42 Bombardment with radiation
• CPC Class Codes: H01L 33/0093 Wafer bonding; Removal of the growth substrate
• CPC Class Codes: H01L 33/14 with a carrier transport control structure, e.g. highly-doped semiconductor layer or current-blocking structure
• CPC Class Codes: H01L 33/382 the electrode extending partially in or entirely through the semiconductor body
• CPC Class Codes: H01L 33/387 with a plurality of electrode regions in direct contact with the semiconductor body and being electrically interconnected by another electrode layer
• CPC Class Codes: H01L 33/405 Reflective materials

Abstract

The present invention discloses a light-emitting diode with enhanced brightness and a method for fabricating the same. The light-emitting diode comprises: an epitaxial LED structure having at least one lighting-emitting active layer with a plurality of spacers inside the lighting-emitting active layer; at least one conductive contact, formed on the bottom surface where no spacer is formed inside the lighting-emitting active layer; a transparent material layer formed in the spacers; an adhesion layer formed between the transparent material layer and a permanent substrate; a bottom electrode formed on the bottom surface of the permanent substrate; and an opposed electrode formed on the top surface of the epitaxial LED structure.

Claims

1. A method for fabricating a light-emitting diode with enhanced brightness, comprising:

forming an epitaxial LED structure having at least one lighting-emitting active layer on a temporary substrate, wherein a highly doped layer is naturally formed at a bottom surface of said lighting-emitting active layer;

splitting off said temporary substrate;

forming at least one conductive contact on a portion of a bottom surface of said highly doped layer;

removing portions of said highly doped layer not overlaid by said conductive contact so that at least one opening is formed in said highly doped layer;

forming a transparent material layer in said opening;

attaching a permanent substrate to a bottom surface of said transparent material layer; and

forming a bottom electrode on a bottom surface of said permanent substrate and forming an opposed electrode on a top surface of said epitaxial LED structure, said opposed electrode being formed on the top surface of said epitaxial LED structure before said temporary substrate is split off and the bottom electrode is formed on the bottom surface of said permanent substrate before said permanent substrate is attached to said transparent material layer.

2. The method of claim 1, further comprising a step of:

forming a reflective layer on the bottom surface of said transparent material layer before attaching said permanent substrate to the bottom of said transparent material layer.

3. The method of claim 1, further comprising a step of:

forming an adhesion layer on a top surface of said permanent substrate and then attaching said permanent substrate to the bottom surface of said transparent material layer by said adhesion layer.

4. The method of claim 1, further comprising a step of:

forming a current diffusion layer on the top surface of said epitaxial LED structure.

5. The method of claim 1, wherein said transparent material layer is selected from the group of conductive materials consisting of ITO, zinc oxide, tin oxide, indium oxide and combinations thereof.

6. The method of claim 1, wherein said transparent material layer is selected from the group of insulating materials consisting of polymer, quartz, glass and combinations thereof.

7. The method of claim 1, wherein said permanent substrate is formed of a material with good thermal conductivity characteristics.

8. The method of claim 7, wherein said permanent substrate is formed of a material selected from the group consisting of Si, BN, AlN, Al₂O₃, MgO, MgO₂ and their combinations thereof.

9. The method of claim 1, further comprising a step of:

forming a planar LED from said epitaxial LED structure and forming a first electrode and a second electrode on the top surface of said epitaxial LED structure.