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

• US 20030173602A1
• Filed: 03/12/2002
• Published: 09/18/2003
• Est. Priority Date: 03/12/2002
• Status: Active Grant

• Current Assignee: Opto Tech Corporation (OptoTech Corp.)
• Original Assignee: Opto Tech Corporation (OptoTech Corp.)
• Inventors: Hsu, Chia-Liang, Tsai, Chang-Da, Lin, San Bao, Lin, Ming-Der, Hsu, Jung-Kuei, Wang, Kwang-Ru, Lu, Hung-Yuan, Hwang, Yung-Chiang, Yu, Hsueh-Chih, Chu, Yen-Hu, Chang, Chui-Chuan
• Granted Patent: US 6,716,654 B2
• Time in Patent Office: Days
• US Class Current: 257/290
• 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 the bottom surface of said lighting-emitting active layer;

splitting off said temporary substrate;

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

removing portions of said highly doped layer that are not connected to said conductive contact so that a spacer is formed between two portions of said highly doped layer;

forming a transparent material layer in said spacer; and

attaching a permanent substrate to the bottom of 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 the top surface of said permanent substrate and then attaching said permanent substrate to the bottom surface of said transparent material layer through said adhesion layer.

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

forming a bottom electrode on the bottom surface of said permanent substrate and forming an opposed electrode on said top surface of said epitaxial LED structure.

5. The method of claim 4, wherein said opposed electrode is 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.

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

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

7. The method of claim 1, wherein said transparent material layer is selected from conductive materials such as ITO, zinc oxide, tin oxide, indium oxide and their combination.

8. The method of claim 1, wherein said transparent material layer is selected from insulating materials such as polymer, quartz, glass and their combination.

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

10. The method of claim 9, wherein said permanent substrate is formed of one of Si, BN, AlN, Al₂O₃, MgO, MgO₂ and their combination.

11. 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.

12. A light-emitting diode with enhanced brightness, comprising:

an epitaxial LED structure having at least one lighting-emitting active layer with a plurality of spacers inside said lighting-emitting active layer;

at least one conductive contact, formed on the bottom surface where no spacer is formed inside said lighting-emitting active layer;

a transparent material layer formed in said spacers;

an adhesion layer formed between said transparent material layer and a permanent substrate;

a bottom electrode formed on the bottom surface of said permanent substrate; and

an opposed electrode formed on the top surface of said epitaxial LED structure.

13. The light-emitting diode of claim 12, further comprising a reflective layer formed between said transparent layer and said adhesion layer.

14. The light-emitting diode of claim 13, wherein said reflective layer and said adhesion layer are formed by said same material.

15. The light-emitting diode of claim 12, further comprising a current diffusion layer formed between said epitaxial LED structure and said opposed electrode.

16. The light-emitting diode of claim 12, wherein said adhesion layer is a bottom electrode.

17. The light-emitting diode of claim 12, wherein said transparent material layer is selected from conductive materials such as ITO, zinc oxide, tin oxide, indium oxide and their combination.

18. The light-emitting diode of claim 12, wherein said transparent material layer is selected from insulating materials such as polymer, quartz, glass and their combination.

19. The light-emitting diode of claim 12, wherein said permanent substrate is formed of a material with good thermal conductivity characteristics.

20. The light-emitting diode of claim 19, wherein said permanent substrate is formed one of Si, BN, AlN, Al₂O₃, MgO, MgO₂ and their combination.

21. The light-emitting diode of claim 12, wherein said LED is selected from a vertical LED and a planar LED.