III-nitride light-emitting devices with one or more resonance reflectors and reflective engineered growth templates for such devices, and methods

• US 7,915,624 B2
• Filed: 08/03/2007
• Issued: 03/29/2011
• Est. Priority Date: 08/06/2006
• Status: Active Grant

• Current Assignee: Lightwave Photonics, Inc.
• Original Assignee: Lightwave Photonics, Inc.
• Inventors: Jorgenson, Robbie J.
• Primary Examiner(s): Nguyen; Dao H
• Assistant Examiner(s): Nguyen; Tram H
• Application Number:
  US11/882,730
• Publication Number:
  US 20080029773A1
• Time in Patent Office: 1,334 Days
• Field of Search: 257/13, 257/14, 257/9, 257 79-103, 257/431, 257/432, 257/E21.371, 257/E21.387, 257E21403-E21407, 257/E21.441, 257/E21.445, 257/E21.448, 257/E21.452, 257/918, 257E51018-E51022, 257E33001-E33077, 257/E33.054, 257/E25.028, 438/22, 438/29, 438/39, 438/400, 438/41, 438/44, 438/46, 438/47
• US Class Current: 257/94
• CPC Class Codes: H01L 33/105 with a resonant cavity structure
• CPC Class Codes: H01L 33/32 containing nitrogen
• CPC Class Codes: H01L 33/405 Reflective materials
• CPC Class Codes: H01L 33/465 with a resonant cavity structure
• CPC Class Codes: H01L 33/60 Reflective elements

Abstract

A light emitter includes a first mirror that is an epitaxially grown metal mirror, a second mirror, and an active region that is epitaxially grown such that the active region is positioned at or close to, at least, one antinode between the first mirror and the second mirror.

Claims

1. A light-emitting device comprising:

a first mirror having a first face and an opposite second face, wherein the first minor includes a metal and is a grown epitaxial metal mirror; and

an epitaxial structure wherein the epitaxial structure is in contract with and covering at least a portion of the first face of the first mirror, the epitaxial structure having an active region configured to emit light, wherein the active region is positioned a first distance away from the first face of the first minor such that the active region is located at or substantially at an antinode of a first standing optical wave produced by interference of light emitted from the active region with light reflected by the first minor to form at least one extraction mode.

2. The device of claim 1, further comprising:

a second mirror covering at least a portion of a face of the epitaxial structure that is opposite the first face of the first minor, wherein the second minor is positioned a second distance away from the active region such that the active region is located at or substantially at an antinode of a second standing optical wave produced by the interference of light emitted from the active region with light reflected by the second minor to form at least one extraction mode.

3. The device of claim 2, wherein:

the first mirror and the second mirror form an optical cavity having an optical cavity length defined by a distance between the first mirror and the second minor.

4. The device of claim 1, further comprising:

a substrate having a first face; and

a group III-nitride structure having a first face on one side of the group III-nitride structure and a second face on an opposite side of the III-nitride structure, wherein the first face of the group III-nitride structure covers at least a portion of the first face of the substrate and the second face of the first metal minor covers at least a portion of the second face of the group III-nitride structure.

5. The device of claim 1, wherein the epitaxial structure further includes:

an n-type group III-nitride layer positioned between the first mirror and the active region; and

a p-type group III-nitride structure covering at least a portion of a face of the active region that is opposite the first face of the first minor.

6. The device of claim 5, wherein the p-type group III-nitride structure includes a p-type AlGaN layer covering at least a portion of the active region and a p-type GaN layer covering at least a portion of the p-type AlGaN layer, and wherein the n-type group III-nitride layer includes an n-type GaN layer.

7. The device of claim 1, wherein the epitaxial structure further includes:

a p-type group III-nitride structure positioned between the first mirror and the active region; and

an n-type group III-nitride layer covering at least a portion of a face of the active region that is opposite the first face of the first mirror.

8. The device of claim 7, wherein the p-type group III-nitride structure includes a p-type AlGaN layer covering at least a portion of the active region and a p-type GaN layer positioned between the p-type AlGaN layer and the first mirror, and wherein the n-type group III-nitride layer includes an n-type GaN layer.

9. The device of claim 1, wherein the first minor has a lattice constant;

and wherein the epitaxial structure has a lattice constant that is substantially matched to the lattice constant of the first mirror.

10. The device of claim 4, wherein the group III-nitride structure has a lattice constant;

wherein the first minor has a lattice constant that is substantially matched to the lattice constant of the group III-nitride structure; and

wherein the epitaxial structure has a lattice constant that is substantially matched to the lattice constant of the first mirror.

11. The device of claim 1, wherein the first minor is partially transmissive and partially reflective to incident light.

12. The device of claim 1, wherein the first minor includes a plurality of layers.

13. The device of claim 1, wherein the first minor includes a nitride of the metal.

14. The device of claim 1, wherein the metal is a transitional metal and the first mirror includes a nitride of the transitional metal.

15. The device of claim 1, wherein the first minor includes a boride of the metal.

16. The device of claim 1, wherein the metal is a transitional metal and the first mirror includes a diboride of the transitional metal.

17. The device of claim 1, wherein the metal includes Hf_xZr_1-x, where x is between 0 and 1, inclusive.

18. The device of claim 1, wherein the metal is in a nitride compound that includes (Hf_xZr_yTi_z)N where x+y+z=1 and where x is between 0 and 1, inclusive, and where y is between 0 and 1, inclusive, and where z is between 0 and 1, inclusive.

19. The device of claim 1, wherein the metal is in a diboride compound that includes (Hf_xZr_yY_z)B₂ where x+y+z=1 and where x is between 0 and 1, inclusive, and where y is between 0 and 1, inclusive, and where z is between 0 and 1, inclusive.

20. The device of claim 2, wherein the second minor is an epitaxially grown minor that includes a metal.

21. The device of claim 2, wherein the second minor is formed other than epitaxially, and includes at least amorphous, or polycrystalline, or microcrystalline structure.

22. The device of claim 2, wherein the second minor is a light-exiting face.

23. The device of claim 2, wherein the second minor is formed by an interface between a semiconductor and a transparent conductor.

24. The device of claim 2, wherein the second minor includes a distributed Bragg reflector.

25. The device of claim 1, wherein the first minor is substantially non-transmissive.

26. The device of claim 1, further comprising:

a photonic crystal structure positioned to cover at least a portion of a face of the epitaxial structure that is opposite the first face of the first mirror.

27. The device of claim 1, wherein the epitaxial structure further includes a photonic-crystal structure.

28. The device of claim 1, further comprising a roughened light-extraction surface positioned to cover at least a portion of a face of the epitaxial structure that is opposite the first face of the first minor.

29. The device of claim 1, further comprising:

a light-exiting surface of the epitaxial structure configured to emit light; and

wherein the first distance is tuned such that a direction of propagation of the first standing optical wave is substantially normal to the light-exiting surface.

30. The device of claim 1, further comprising:

a light-exiting surface of the epitaxial structure configured to emit light, the light-exiting surface having a surface normal; and

wherein the first distance is reduced in order to detune the first distance such that a direction of propagation of the first standing optical wave is angled away from the surface normal of the light-exiting surface and is extracted through the light-exiting surface.

31. The device of claim 1, wherein the distance between the active region and first mirror is within a micro-cavity regime.

32. The device of claim 2, further comprising:

a light-exiting surface of the epitaxial structure configured to emit light; and

wherein a direction of propagation of the second standing optical wave is substantially normal to the light-exiting surface.

33. The device of claim 2, further comprising:

a light-exiting surface of the epitaxial structure configured to emit light, the light-exiting surface having a surface normal; and

wherein the second distance is reduced in order to detune the second distance such that a direction of propagation of the second standing optical wave is angled away from the surface normal of the light-exiting surface and is extracted through the light-exiting surface.

34. The device of claim 2, wherein the distance between the active region and second minor is within a micro-cavity regime.

35. The device of claim 3, further comprising:

a light-exiting surface of the epitaxial structure configured to emit light; and

wherein the cavity length is selected such that a direction of propagation of the first standing optical wave and a direction of propagation of the second standing optical wave are both substantially normal to the light-exiting surface.

36. The device of claim 3, further comprising:

a light-exiting surface of the epitaxial structure configured to emit light, wherein the light-exiting surface further comprises a surface normal; and

wherein the cavity length is reduced in order to detune the cavity length such that a direction of propagation of the first standing optical wave and a direction of propagation of the second standing optical wave are each angled away from the surface normal of the light-exiting surface and are extracted through the light-exiting surface.

37. The device of claim 3, wherein the cavity length is within a micro-cavity regime.

38. The device of claim 4, wherein the substrate is substantially transparent to light of a wavelength emitted by the active region.

45. The device of claim 1, further comprising:

a light-exiting surface of the epitaxial structure configured to emit light; and

wherein the first face of the first mirror has a surface normal and the first distance is reduced in order to detune the first distance such that a direction of propagation of the first standing optical wave is angled away from the surface normal of the first face of the first minor and is extracted through the light-exiting surface.

46. The device of claim 2, further comprising:

a light-exiting surface of the epitaxial structure configured to emit light; and

wherein the first face of the first mirror has a surface normal and the first distance is reduced in order to detune the first distance such that a direction of propagation of the first standing optical wave is angled away from the surface normal of the first face of the first minor and is extracted through the light-exiting surface.

47. The device of claim 3, further comprising:

a light-exiting surface of the epitaxial structure configured to emit light; and

wherein the first face of the first mirror has a surface normal and the first distance is reduced in order to detune the first distance such that a direction of propagation of the first standing optical wave is angled away from the surface normal of the first face of the first minor and is extracted through the light-exiting surface.

39. An apparatus comprising

an epitaxially grown structure that includes:

a crystalline group III-nitride layer having a first face and a second face opposite the first face; and

an epitaxially grown planar specular layer is in contact with and covering at least a portion of the first face of the crystalline group III-nitride layer, wherein the planar specular layer includes a metal.

40. The structure of claim 39, further comprising a substrate covering at least a portion of the second face of the crystalline group III-nitride layer, the substrate having a composition that includes at least one of the following:

silicon, a sapphire, a silicon carbide, a zinc oxide, a spinel, MgAl₂O₄, AlN, GaP, MgO, LiGaO₂, LiAlO₂, NdGaO₃, ScAlMgO₄, Ca₈La₂(PO₄)₆O₂, Zr, Hf, Zr_xHf_(1-x)B₂, Zr_xHf_(1-x)N, ScN, TiN, and NbN, where x is between 0 and 1, inclusive.

41. The structure of claim 39, wherein the planar specular layer has a composition that includes at least one of the following:

Hf_xZr_1-x, where x is between 0 and 1, inclusive, and

(Hf_xZr_yTi_z)N, where x+y+z=1, where x is between 0 and 1, inclusive, where y is between 0 and 1, inclusive, and where z is between 0 and 1, inclusive; and

(Hf_xZr_yY_z)B₂, where x+y+z=1 where x is between 0 and 1, inclusive, where y is between 0 and 1, inclusive, and where z is between 0 and 1, inclusive.

42. The structure of claim 39 further comprising:

a second group III-nitride layer grown epitaxially, the second group III-nitride layer covering at least a portion of the planar specular layer, wherein the second group III-nitride layer has a predetermined thickness that corresponds to the positioning of an epitaxially grown active region at or substantially at an antinode of a standing optical wave produced by interference of light emitted from the active region with light reflected by the planar specular layer.

43. A method of fabricating a light-emitting device, the method comprising:

providing a substrate having a group III-nitride structure thereon;

epitaxially growing a first mirror on at least a portion of a face of the group III-nitride structure, wherein the first mirror includes a metal;

epitaxially growing a light-emitting device (LED) structure is in contact with at least a portion of a first face of the first minor, the LED structure having an active region configured to emit light; and

forming a second minor on at least a portion of a face of the LED structure that is opposite the first face of the first minor, wherein the first minor and the second mirror are each spaced from the active region such that the first minor and the second mirror form an optical cavity having an optical cavity length between the first mirror and the second minor, and such that the active region is located at or substantially at an antinode of a standing optical wave of the optical cavity.

44. The method of claim 43, wherein the epitaxially growing of the LED structure further includes:

epitaxially growing an n-type group III-nitride layer on at least a portion of the first mirror;

forming the active region on at least a portion of the n-type group III-nitride layer; and

epitaxially growing a p-type group III-nitride structure on at least a portion of the active region.