Polarization-reversed III-nitride light emitting device

• US 20060202215A1
• Filed: 03/14/2005
• Published: 09/14/2006
• Est. Priority Date: 03/14/2005
• Status: Active Grant

• Current Assignee: Lumileds LLC (Apollo Global Management, Inc.)
• Original Assignee: Lumileds Lighting US LLC (Apollo Global Management, Inc.)
• Inventors: Krames, Michael R., Epler, John E., Wierer, Jonathan J. Jr., Craford, M. George
• Granted Patent: US 7,804,100 B2
• Time in Patent Office: Days
• US Class Current: 257/94
• CPC Class Codes: H01L 33/0093 Wafer bonding; Removal of the growth substrate
• CPC Class Codes: H01L 33/16 with a particular crystal structure or orientation, e.g. polycrystalline, amorphous or porous
• CPC Class Codes: H01L 33/32 containing nitrogen
• CPC Class Codes: H01S 2304/00 Special growth methods for semiconductor lasers
• CPC Class Codes: H01S 5/0213 Sapphire, quartz or diamond based substrates
• CPC Class Codes: H01S 5/0215 Bonding to the substrate
• CPC Class Codes: H01S 5/0217 Removal of the substrate
• CPC Class Codes: H01S 5/02208 characterised by the shape of the housings
• CPC Class Codes: H01S 5/320225 polar orientation
• CPC Class Codes: H01S 5/32341 blue laser based on GaN or GaP

Abstract

A device structure includes a III-nitride wurtzite semiconductor light emitting region disposed between a p-type region and an n-type region. A bonded interface is disposed between two surfaces, one of the surfaces being a surface of the device structure. The bonded interface facilitates an orientation of the wurtzite c-axis in the light emitting region that confines carriers in the light emitting region, potentially increasing efficiency at high current density.

Claims

1. A structure comprising:

a device structure comprising a III-nitride light emitting region disposed between a p-type region and an n-type region, the light emitting region comprising a wurtzite crystal structure; and

a bonded interface disposed between two surfaces, wherein one of the surfaces is a surface of the device structure;

wherein across an interface disposed between the light emitting region and the p-type region, a wurtzite c-axis, defined as pointing from a nitrogen face of a III-nitride unit cell to a gallium face of a III-nitride unit cell, points toward the light emitting region.

2. The structure of claim 1 wherein the two surfaces are both GaN.

3. The structure of claim 1 wherein one of the two surfaces is selected from the group GaN, AlN, InGaN, SiC, and Si.

4. The structure of claim 1 wherein the surface of the device structure is a III-nitride surface that is one of p-type, n-type, and undoped.

5. The structure of claim 1 wherein one of the two surfaces comprises a dielectric layer.

6. The structure of claim 5 wherein the dielectric layer is selected from the group SiO₂, Si₃N₄, SiON, TiO₂, SiO₂, SnO₂, ZrO₂, ZnO,MgF₂, and Al₂O₃.

7. The structure of claim 1 wherein one of the two surfaces is textured.

8. The structure of claim 7 wherein the textured surface comprises a periodic array of holes formed in the textured surface.

9. The structure of claim 8 wherein the periodic array of holes has a lattice constant between 0.1λ

, and 4λ

, wherein λ

is a wavelength of light in the light emitting region.

10. The structure of claim 1 wherein the bonded interface is a semiconductor bond and is substantially free of metal.

11. The structure of claim 1 further comprising a metal layer disposed at the bonded interface.

12. The structure of claim 1 further comprising a metal-semiconductor alloy disposed at the bonded interface.

13. The structure of claim 1 further comprising contacts electrically connected to the n-type region and the p-type region.

14. The structure of claim 1 further comprising:

a mesa including a portion of the light emitting region; and

laser facets disposed on opposite ends of the mesa.

15. A method of forming a semiconductor light emitting device, the method comprising:

providing an epitaxial structure grown on a growth substrate;

bonding the epitaxial structure to a host structure by a bond between two surfaces, wherein at least one of the surfaces is a III-nitride surface;

removing the growth substrate to expose a surface of the epitaxial structure;

after removing the growth substrate, forming a p-type region on or in the epitaxial structure.

16. The method of claim 15 wherein providing an epitaxial structure comprises growing a III-nitride structure over a growth substrate such that the surface exposed by removing the growth substrate is a nitrogen-face of a wurtzite III-nitride unit cell.

17. The method of claim 15 further comprising thinning the epitaxial structure after removing the growth substrate.

18. The method of claim 15 wherein forming a p-type region comprises diffusing or implanting p-type dopant into a semiconductor region.

19. The method of claim 15 wherein forming a p-type region comprises annealing an exposed surface of the epitaxial structure.

20. The method of claim 15 wherein forming a p-type region comprises growing a p-type region.

21. The method of claim 15 wherein the epitaxial structure comprises:

a first region grown over the growth substrate;

a light emitting region grown over the first region; and

an n-type region grown over the light emitting layer.

22. The method of claim 21 wherein bonding comprises bonding the host structure to the epitaxial structure such that the n-type region is disposed between the light emitting region and the bond.

23. The method of claim 22 further comprising after removing the growth substrate, thinning the first region.

24. The method of claim 22 further comprising diffusing or implanting a p-type dopant into a remaining portion of the first region.

25. The method of claim 24 further comprising annealing the remaining portion after diffusing or implanting.

26. The method of claim 22 further comprising growing a p-type region over a remaining portion of the first region.

27. The method of claim 21 wherein:

the epitaxial structure is a first epitaxial structure and the growth substrate is a first growth substrate; and

the host structure comprises;

a second growth substrate; and

a second epitaxial structure grown over the second growth substrate.

28. The method of claim 27 wherein bonding comprises bonding the second epitaxial structure to the first epitaxial structure such that the n-type region is disposed between the light emitting region and the bond, and wherein removing comprises removing the first growth substrate.

29. The method of claim 15 wherein the epitaxial structure comprises:

a p-type region grown over the growth substrate;

a light emitting region grown over the p-type region; and

an n-type region grown over the light emitting region.

30. The method of claim 29 wherein bonding comprises bonding the epitaxial structure to the host structure such that the n-type region is disposed between the light emitting region and the bond.

31. The method of claim 30 further comprising after removing the growth substrate, thinning the p-type region.

32. The method of claim 31 further comprising annealing the p-type region remaining after thinning.

33. The method of claim 32 wherein annealing comprises annealing in NH₃.

34. The method of claim 30 further comprising growing an additional p-type region over a portion of the p-type region remaining after removing the growth substrate.

35. The method of claim 30 further comprising diffusing or implanting a p-type dopant into a portion of the p-type region remaining after removing the growth substrate.

36. The method of claim 29 wherein:

the epitaxial structure is a first epitaxial structure and the growth substrate is a first growth substrate; and

the host structure comprises;

a second growth substrate; and

a second epitaxial structure grown over the second growth substrate.

37. The method of claim 36 wherein bonding comprises bonding the first epitaxial structure to the second epitaxial structure such that the n-type region is disposed between the light emitting region and the bond, and wherein removing comprises removing the first growth substrate.

38. The method of claim 15 wherein the host structure comprises a distributed Bragg reflector.

39. The method of claim 15 wherein the epitaxial structure includes a light emitting region, the method further comprising:

forming a mesa including a portion of the light emitting region; and

forming laser facets on opposite ends of the mesa.