Method of fabricating high efficiency light-emitting diode with a transparent substrate

• US 6,458,612 B1
• Filed: 09/19/2001
• Issued: 10/01/2002
• Est. Priority Date: 09/19/2000
• Status: Active Grant

• Current Assignee: Epistar Corporation
• Original Assignee: United Epitaxy Company (Epistar Corporation)
• Inventors: Chang, Chih-Sung, Chen, Tzer-Perng, Chiou, Shu-Woei
• Primary Examiner(s): Thompson, Craig
• Application Number:
  US09/955,168
• Publication Number:
  US 20020034835A1
• Time in Patent Office: 377 Days
• Field of Search: 438/29, 438/22-28, 438/46-47, 438/30-45, 438/800, 324/767
• US Class Current: 438/29
• CPC Class Codes: H01L 33/0066 with a substrate not being a III-V compound
• CPC Class Codes: H01L 33/0093 Wafer bonding; Removal of the growth substrate

Abstract

A method for fabricating high efficiency light-emitting diode (LED) adhered to a transparent substrate is disclosed. To begin with, forming a semiconductor substrate, is followed by sequentially forming an etching stopper, a first type ohmic contact layer, a double heterostructure and a second ohmic contact layer. Afterwards, the transparent substrate, such as preferably glass, is adhered onto the second ohmic contact layer and then the GaAs substrate is removed away. After that, the first type cladding layer and the undoped active layer is etched in turn by using the second type ohmic contact layer as the etching stopper. Finally, a first electrode is formed on the first type ohmic contact layer and a second electrode is formed on the second type ohmic contact layer, respectively. The present invention utilizes some features, such as high transmittance and lower absorptivity, of the glass adhered to the second ohmic contact layer to visible light for increasing luminous intensity of the LED. Moreover, the absorption of visible light of the GaAs substrate can be significantly improved by decreasing the use of the GaAs material.

Claims

1. A method of fabricating a high efficiency light-emitting diode, comprising the steps of:

forming a first type ohmic contact layer on a semiconductor substrate;

forming a double heterostructure on said first type ohmic contact layer wherein said double heterostructure having a first type cladding layer, an undoped active layer and a second type cladding layer;

forming a second type ohmic contact layer on said second type cladding layer;

adhering a transparent subtrate to said second type ohmic contact layer;

performing an etching step to remove said semiconductor substrate;

etching said first type cladding layer and said undoped active layer by using said second type ohmic contact layer as an etching stopper;

forming a first electrode on said first type ohmic contact layer; and

forming a second electrode on said second type ohmic contact layer.

2. The method of claim 1, wherein said second type is P-type if said first type is N-type.

3. The method of claim 1, wherein said second type is N-type if said first type is P-type.

4. The method of claim 1, wherein said semiconductor substrate comprises a material of GaAs.

5. The method of claim 1, wherein said first type cladding layer comprises a material of AlGaInP.

6. The method of claim 1, wherein said second type cladding layer comprises a material of AlGaInP.

7. The method of claim 1, wherein said undoped active layer comprises a material of AlGaInP.

8. The method of claim 7, wherein said AlGaInP comprises an ((Al_xGa₁₋

x)_yIn<sub>1−

y</sub>P) compound with 0≦

x≦

1 and 0≦

y≦

1.

9. The method of claim 1, wherein said transparent substrate is the one selected a group consisting of glass, sapphire and GaP which are visible in the range of visible light.

10. The method of claim 1, further comprising a roughing step for the surface of said transparent substrate layer after said transparent substrate layer is adhered to said second ohmic contact layer.

11. The method of claim 10, wherein said roughing step is the one selected a group consisting of a gravel-sprayed technique and chemical etching.

12. A method of fabricating a high efficiency light-emitting diode, comprising the steps of:

sequentially forming a first type ohmic contact layer and a double heterostructure on a semiconductor substrate wherein said double heterostructure having a first type cladding layer, an undoped active layer and a second type cladding layer;

forming a second type ohmic contact layer on said second type cladding layer;

forming a transparent substrate on said second ohmic contact layer by hot-adhering technique;

roughing said transparent substrate to acquire a rugged surface;

performing an etching step to remove said semiconductor substrate;

etching said first type cladding layer and said undoped active layer by using said second type ohmic contact layer as an etching stopper;

forming a first electrode on said first type ohmic contact layer; and

forming a second electrode on said second type ohmic contact layer.

13. The method of claim 12, wherein said second type is P-type if said first type is N-type.

14. The method of claim 12, wherein said second type is N-type if said first type is P-type.

15. The method of claim 12, wherein said semiconductor substrate comprises a material of GaAs.

16. The method of claim 12, wherein said first type cladding layer comprises a material of AlGaInP.

17. The method of claim 12, wherein the step of roughing said transparent substrate layer is the one selected a group consisting of a gravel-sprayed technique and chemical etching.

18. The method of claim 12, wherein said undoped active layer comprises a material of AlGaInP.

19. The method of claim 18, wherein said AlGaInP comprises an ((Al_xGa₁₋

x) _yIn<sub>1−

y</sub>P) compound material 0≦

x≦

1 and 0≦

y≦

1.

20. The method of claim 12, wherein said transparent substrate is the one selected a group consisting of glass, sapphire and GaP which are visible in the range of visible light.