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

• US 20080029773A1
• Filed: 08/03/2007
• Published: 02/07/2008
• Est. Priority Date: 08/06/2006
• Status: Active Grant

• Current Assignee: Lightwave Photonics, Inc.
• Original Assignee: Lightwave Photonics, Inc.
• Inventors: Jorgenson, Robbie J.
• Granted Patent: US 7,915,624 B2
• Time in Patent Office: Days
• 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 emitter comprising:

a) a first mirror that is an epitaxially grown metal mirror;

b) a second mirror;

c) an active region 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.

2. The light emitter of claim 1, wherein the first mirror:

is grow on a III-nitride structure

3. The light emitter of claim 1 further comprising:

a) n-type III-nitride layer between the first and the second mirror; and

b) p-type III-nitride layer between the first and the second mirror.

4. The light emitter of claim 1 further comprising:

p-AlGaN layer between the first and the second mirror.

5. The light emitter of claim 1, wherein the first mirror is partially transparent and partially reflective to light

6. The light emitter of claim 1 further comprising:

a substrate that is transparent.

7. The light emitter of claim 1, wherein the first mirror is reflective and non-transparent to light.

8. The light emitter of claim 3, wherein the n-type III-nitride layer is epitaxially grown to have thickness that locates the center of the active region at or close to an anti-node of a standing optical wave.

9. The light emitter of claim 3, wherein the p-type III-nitride layer is epitaxially grown to have thickness that locates the center of the active region at or close to an anti-node of a standing optical wave.

10. The light emitter of claim 1, wherein a cavity length L_C is equal to d1+d2, where

d1=the distance between the center of the active region and the GEMM

˜

(0.25λ

/N)+M(0.5λ

/N)−

PD1; and

d2=the distance between the center of the active region and the second mirror

˜

(0.25λ

/N)+M(0.5λ

/N)−

PD2 if the second mirror is a metal, and

˜

(0.75λ

/N)+M(0.5λ

/N) if the second mirror is a distributed Bragg reflector,

where λ

is the wave length of light generated by the active region in vacuum, N is the index of refraction of the III-nitride material, M is an integral multiple of half wave lengths within the III-nitride material starting at zero and PD1 and PD2 are the penetration depths of the light into the first and second mirrors, respectively.

11. The light emitter of claim 1 wherein the active region thickness has a width of less than 0.25λ

/N to maintain the active region to be located at or close to an antinode of an standing optical wave where λ

is the wave length of light generated by the active region in vacuum, N is the index of refraction of the III-nitride material.

12. The light emitter of claim 11 wherein the active region placement has a maximum deviation, defined by 0.125(λ

/N)−

0.5(W_AR) where W_AR is the active region width, λ

is the wave length of light generated by the active region in vacuum, N is the index of refraction of the III-nitride material.

13. The light emitter of claim 1, wherein the first mirror composition is at least one of the following:

Zr and Hf and (Hf_xZr_1-x, where x is between 0 and

     1), and

ZrN and HfN and TiN and (Hf_xZr_yY_zN where x+y+z=1), and

ZrB2 and HfB2 and YB2 and (Hf_xZr_yY_zB₂ where x+y+z=1).

14. The light emitter of claim 1, wherein the second mirror is an epitaxial metal mirror.

15. The light emitter of claim 1, wherein the second mirror

is a non-epitaxial metal mirror that includes amorphous, polycrystalline, and microcrystalline.

16. The light emitter of claim 1, wherein the second mirror is a distributed Bragg reflector.

17. The light emitter of claim 1, wherein the second mirror is a semiconductor/air interface.

18. The light emitter of claim 1, wherein the second mirror is a semiconductor/epoxy interface.

19. The light emitter of claim 1, wherein the second mirror is a semiconductor/transparent conductor interface.

20. The light emitter of claim 1, further comprising a photonic crystal structure.

21. The light emitter of claim 1, wherein the second mirror is a photonic crystal light extraction surface.

22. The light emitter of claim 1, further comprising a roughened light extraction surface.

23. The light emitter of claim 1, wherein the second mirror is a roughened light extraction surface.

24. The light emitter of claim 1 wherein the cavity length, L_c is detuned;

where the emission wavelength is longer than the normal cavity mode wavelength, being that the light emitted propagates within an off axis mode that has an angle from the on axis mode below the Snell'"'"'s window critical angle.

25. Then light emitter of claim 1 wherein the cavity length, L_c is within the micro-cavity regime being that the cavity is small enough that the cavity order Int(2NL_c/λ

) is less than 2N², where L_c is the cavity length, N is the index of refraction, and λ

is the wavelength of light in a vacuum.

26. An epitaxy growth structure comprising:

a) a crystalline III-nitride layer; and

b) planar specular grown epitaxial metal mirror layer grown over the crystalline III-nitride layer

27. The structure of claim 26 further comprising a substrate having a composition of at least one of the following:

Sapphire, Silicon Carbide, Zinc Oxide, Spinel (MgAl₂O₄), AlN, GaP, MgO, LiGaO₂, LiAlO₂, NdGaO₃, ScAlMgO₄, Ca₈La₂(PO₄)₆O₂.

28. The structure of claim 26, wherein the metal layer having a composition of at least one of the following:

Zr and Hf and (Hf_xZr_1-x, where x is between 0 and

     1), and

ZrN, HfN, TiN and the like (Hf_xZr_yY_zN where x+y+z=1), and

ZrB2, HfB2, YB2 and the like (Hf_xZr_yY_zB₂ where x+y+z=1).

29. The structure of claim 26, wherein the metal layer having a predetermined thickness ≦

150 nm such that the transparency to light shorter than 700 nm in wavelength is greater than zero for the use of resonant cavity light emitting diode construction.

30. The structure of claim 26 wherein the metal layer having a predetermined thickness ≧

150 nm such that the reflectivity to light shorter than 700 nm in wavelength is greater than zero.

31. The structure of claim 26 further comprising:

a second III-nitride layer grown epitaxially on the grown epitaxial metal mirror layer

32. The structure of claim 31 wherein:

said the second III-nitride layer being of a predetermined thickness which corresponds to the positioning of epitaxially grown active region at or close to an antinode.