Light-emitting diode on a conductive substrate

1. A method of forming a light-emitting diode (LED) device, the method comprising:

providing a silicon-on-insulator (SOI) substrate comprising a silicon substrate, a buried oxide layer, and a topmost silicon layer, wherein the topmost silicon layer contains a porous layer;

forming an LED structure over the topmost silicon layer of the SOI substrate;

forming a conductive substrate over the LED structure in a manner such that the LED structure is disposed between the porous layer and the conductive substrate; and

etching the porous layer to separate the silicon substrate from the LED structure.

2. The method of claim 1 , further comprising removing the topmost silicon layer from the LED structure.

3. The method of claim 1 , wherein the step of etching the porous layer comprises exposing the porous layer to a hydrofluoric-acid solution.

4. The method of claim 1 , wherein the forming the conductive substrate over the LED structure is performed at least in part by electroplating.

5. The method of claim 4 , wherein the electroplating comprises electroplating nickel.

6. The method of claim 1 , wherein the forming the conductive substrate comprises forming a doped silicon layer over the LED structure.

7. The method of claim 1 , wherein the forming the conductive substrate comprises bonding a second silicon substrate to the LED structure.

8. The method of claim 7 , wherein the second silicon substrate comprises a silicon substrate doped with p-type ions.

9. A method of fabricating a light-emitting diode (LED) device, comprising:

providing a first substrate;

forming a porous layer on the first substrate;

forming an LED structure over the porous layer, wherein the LED structure includes a light-emitting layer disposed between a first group III-V compound layer and a second group III-V compound layer, the first and second group III-V compound layers having different types of conductivity;

attaching a second substrate to the LED structure, such that the LED structure is disposed between the first substrate and the second substrate; and

cleaving the porous layer, thereby separating the first substrate from the LED structure and the second substrate.

10. The method of claim 9 , wherein the forming the porous layer comprises converting a portion of the substrate into the porous layer through an electro-chemical anodization process.

11. The method of claim 9 , wherein the cleaving the porous layer comprises performing a water jet mechanical detach process to the porous layer.

12. The method of claim 9 , wherein the cleaving the porous layer comprises performing a chemical etch process to the porous layer.

13. The method of claim 9 , wherein the first substrate comprises a bulk silicon substrate.

14. The method of claim 9 , wherein the first substrate comprises a silicon-on-insulator (SOI) substrate, a sapphire substrate, or a silicon carbide substrate.

15. The method of claim 9 , wherein the second substrate comprises a conductive substrate.

16. The method of claim 9 , further comprising:

forming a seed layer between the porous layer and the LED structure; and

removing the seed layer after the cleaving the porous layer.

17. The method of claim 9 , further comprising: forming a reflective layer between the LED structure and the second substrate.

18. A method of fabricating a light-emitting diode (LED) device, comprising:

providing a bulk silicon substrate;

converting a surface portion of the bulk silicon substrate into a porous layer;

forming a seed layer over the porous layer;

forming an LED structure over the seed layer, wherein the LED structure includes a light-emitting layer disposed between a first group III-V compound layer and a second group III-V compound layer, the first and second group III-V compound layers having different types of conductivity;

bonding a conductive substrate to the LED structure, such that the bulk silicon substrate and the conductive substrate are disposed on opposite sides of the LED structure; and

separating the bulk silicon substrate from the LED structure and the conductive substrate at least in part by cleaving the porous layer through a mechanical detach process or through an etching process.

19. The method of claim 18 , wherein the converting comprises performing an electro-chemical anodization process to the surface portion of the bulk silicon substrate.

20. The method of claim 18 , wherein:

the mechanical detach process comprises applying a stream of water laterally to the porous layer; and

the etch process comprises applying a hydrofluoric acid to the porous layer.

21. The method of claim 18 , further comprising: forming a reflective layer between the LED structure and the conductive substrate.