Optical device structure using GaN substrates for laser applications
View Patent ↗An optical device includes a gallium nitride substrate member having an m-plane nonpolar crystalline surface region characterized by an orientation of about −1 degree towards (000-1) and less than about +/−0.3 degrees towards (11-20). The device also has a laser stripe region formed overlying a portion of the m-plane nonpolar crystalline orientation surface region. In a preferred embodiment, the laser stripe region is characterized by a cavity orientation that is substantially parallel to the c-direction, the laser stripe region having a first end and a second end. The device includes a first cleaved c-face facet, which is coated, provided on the first end of the laser stripe region. The device also has a second cleaved c-face facet, which is exposed, provided on the second end of the laser stripe region.
1. An optical device comprising:
a gallium and nitrogen containing substrate member having an m-plane nonpolar crystalline surface region characterized by an off-cut orientation;
a laser stripe region formed overlying a portion of the m-plane nonpolar crystalline orientation surface region, the laser stripe region being characterized by a cavity orientation substantially parallel to the c-direction, the laser stripe region having a first end and a second end;
a first cleaved c-face facet provided on the first end of the laser stripe region, the first cleaved c-face facet being characterized by a first scribed region;
a second cleaved c-face facet provided on the second end of the laser stripe region, the second cleaved c-face facet being characterized by a second scribed region; and
a wall plug efficiency of 14 percent and greater characterizing the optical device for at least 60 mWatt of optical output power.
2. The device of claim 1 wherein the first cleaved c-face facet is substantially parallel with the second cleaved c-face facet.
3. The device of claim 1 wherein the off-cut orientation is about +/−1 degrees toward (0001) and less than about 0.3 degree toward (11-20).
4. The method of claim 1 wherein the optical device operating in a single lateral mode is characterized by a wall plug efficiency of 16% and greater.
5. The method of claim 1 wherein the optical device operating in a single lateral mode is characterized by a wall plug efficiency of 20% and greater or 25% and greater.
6. The device of claim 1 wherein the laser stripe comprises a length ranging from about 200 microns to about 2000 microns and wherein the device operates with only a single-lateral optical mode.
7. The device of claim 1 wherein the laser stripe comprises a from about 300 microns to about 900 microns.
8. The device of claim 1 wherein the laser stripe comprises a width ranging from about 1 micron to about 2 microns.
9. The device of claim 1 wherein the laser stripe comprises a width ranging from about 2 micron to about 15 microns.
10. The device of claim 1 further comprising spontaneously emitted light polarized perpendicular to the c-direction wherein the spontaneous emitted light is characterized by a polarization ratio greater than 0.3 for a spontaneous emission peak wavelength greater than 430 nm.
11. The device of claim 1 further comprising spontaneously emitted light or stimulated emitted light characterized by a wavelength ranging from about 385 to about 425 nanometers.
12. The device of claim 1 further comprising spontaneously emitted light or stimulated emitted light characterized by a wavelength ranging from about 425 to about 470 nanometers.
13. The device of claim 1 further comprising spontaneously emitted light or stimulated emitted light characterized by a wavelength ranging from about 470 to about 500 nanometers.
14. The device of claim 1 wherein the laser stripe is provided by an etching process selected from dry etching and wet etching.
15. The device of claim 1 further comprising an n-type metal region overlying a backside of the gallium and nitrogen containing substrate member and a p-type metal region overlying an upper portion of the laser stripe.
16. The device of claim 1 wherein the laser stripe comprises an overlying dielectric layer exposing an upper portion of the laser stripe.
17. The device of claim 1 , wherein the off-cut orientation is about +17 degrees to about −17 degrees toward (0001).
18. The device of claim 1 , wherein the first scribed region characterizing the first cleaved c-face facet is a laser scribed region or a diamond scribed region.
19. The device of claim 1 , wherein the second scribed region characterizing the second cleaved c-face facet is a laser scribed region or a diamond scribed region.
20. The device of claim 1 wherein the off-cut orientation is about −2 degrees to about +2 degrees toward (0001) and less than about +/−0.5 degrees toward (11-20).
21. The device of claim 1 wherein the first cleaved c-face facet comprises a first mirror surface.
22. The device of claim 21 wherein the first mirror surface is provided by a scribing and breaking process from either a front side or a backside of the gallium and nitrogen containing substrate member.
23. The device of claim 22 wherein the first mirror surface comprises a coating to modify the reflection characteristic.
24. The device of claim 23 wherein the coating is selected from silicon dioxide, hafnia, titania, Ta 2 O 5 , and Al 2 O 3 .
25. The device of claim 23 wherein the first mirror surface comprises an anti-reflective coating.
26. The device of claim 1 wherein the second cleaved c-face facet comprises a second mirror surface.
27. The device of claim 26 wherein the second mirror surface is provided by a scribing and breaking process.
28. The device of claim 26 wherein the second mirror surface comprises a coating configured to modify the reflection characteristic as a backside surface.
29. The device of claim 28 wherein the coating is selected from silicon dioxide, hafnia, titania, Ta 2 O 5 , and Al 2 O 3 .
30. The device of claim 26 wherein the second mirror surface is substantially free from a coating and exposes a gallium and nitride material.
31. The device of claim 1 further comprising an n-type gallium nitride region overlying the surface region, an active region overlying the n-type gallium nitride region, and the laser stripe region overlying the active region.
32. The device of claim 31 wherein the active region comprises three to seven quantum well regions, the three to seven well regions characterized by a thickness of 2 nm to about 4 nm.
33. The device of claim 31 wherein the active region comprises three to seven quantum well regions, the three to seven quantum well regions characterized by a thickness of 4 nm to about 6 nm.
34. The device of claim 31 wherein the active region comprises three to seven quantum well regions, the three to seven well regions characterized by a thickness of 6 nm to about 10 nm.
35. The device of claim 31 wherein the active region comprises a plurality of barrier regions separating each of the quantum well regions, each of the barrier regions ranges in thickness from 1 nm to 2 nm.
36. The device of claim 31 wherein the active region comprises a plurality of barrier regions separating each of the quantum well regions, wherein each of the barrier regions ranges in thickness 1.5 nm to 2.5 nm.
37. The device of claim 31 wherein the active region comprises a plurality of barrier regions separating each of the quantum well regions, wherein each of the barrier regions ranges is characterized by a thickness of 2.5 nm or less.
38. The device of claim 31 comprising an electron blocking region overlying the active region.
39. The device of claim 31 comprising a separate confinement hetero-structure overlying the n-type gallium nitride region.
40. The device of claim 31 , wherein the active region comprises three to seven quantum well regions, the three to seven well regions characterized by a thickness of 6 nm to about 12 nm.
41. The device of claim 31 , wherein the active region comprises a plurality of barrier regions separating each of the quantum well regions, wherein each of the barrier regions ranges in thickness from 1.5 nm to 2.5 nm.
42. The device of claim 31 , wherein the active region comprises a plurality of barrier regions separating each of the quantum well regions, each of the barrier regions characterized by a thickness of 2.5 nm and less.
43. The device of claim 31 , wherein the active region comprises a plurality of barrier regions separating each of the quantum well regions, wherein each of the barrier regions ranges in thickness from 1 nm to 2 nm.
44. A method for forming an optical device comprising:
providing a gallium nitride substrate member having an m-plane nonpolar crystalline surface region characterized by forming a laser stripe region overlying a portion of the m-plane nonpolar crystalline orientation surface region, the laser stripe region being characterized by a cavity orientation substantially parallel to the c-direction, the laser stripe region having a first end and a second end;
forming a pair of cleaved facets including a first cleaved c-face facet provided on the first end of the laser stripe region and a second cleaved c-face facet provided on the second end of the laser stripe region;
subjecting the first cleaved c-face facet to at least a deposition process; and
maintaining the second cleaved c-facet substantially exposed gallium and nitrogen containing material.
45. The method of claim 44 wherein the coating of the first cleaved c-face facet comprises a reflective material; and wherein the forming of the pair comprises separately forming of the first cleaved c-face facet and forming the second cleaved c-face facet.
46. The method of claim 44 wherein the pair of cleaved face facets is formed before a singulating process; and wherein the orientation of about −1 degree towards (0001) and less than about 0.3 degrees towards (11-20).
47. The method of claim 44 wherein the optical device operating in the single lateral mode is configured as single lateral mode or multi-mode.
48. The method of claim 44 wherein the optical device operating in the single lateral mode is characterized by a wall plug efficiency of 14% and greater.
49. The method of claim 44 wherein the optical device operating in the single lateral mode is characterized by a wall plug efficiency of 18% or 20% or 23% and greater.
50. A single lateral mode optical device operable in a wavelength regime of 435 nm to 470 nm comprising:
a gallium and nitrogen containing substrate member having an m-plane nonpolar crystalline surface region;
a laser stripe region overlying a portion of the m-plane nonpolar crystalline orientation surface region, the laser stripe region being characterized by a cavity orientation substantially parallel to the c-direction, the laser stripe region having a first end and a second end; and
a peak wall plug efficiency of the single lateral mode laser device of 15% and greater.
51. An optical device comprising:
a gallium and nitrogen containing substrate member having an m-plane nonpolar crystalline surface region;
an n-type gallium nitride region overlying the surface region;
an active region overlying the n-type gallium nitride region;
a plurality of quantum well regions configured within the active region;
a barrier region separating at least a pair of quantum well regions; and
a laser stripe region overlying a portion of the m-plane nonpolar crystalline orientation surface region, the laser stripe region being characterized by a cavity orientation substantially parallel to the c-direction, the laser stripe region having a first end and a second end.
52. The device of claim 51 wherein the barrier region comprises a material selected from GaN, InGaN, AlGaN, and InAlGaN.
53. The device of claim 51 wherein the barrier region is characterized by a thickness ranging from about 1.5 nm to 3 nm; and the optical devices is characterized by a wall plug efficiency of 14% and greater.
54. The device of claim 51 wherein the barrier region is characterized by a thickness ranging from about 1 nm to about 10 nm.
55. The device of claim 51 , wherein the barrier region is characterized by a thickness ranging from 1.5 nm to 2.5 nm.
56. The device of claim 51 , wherein the barrier region is characterized by a thickness of 2.5 nm and less.
57. A laser device comprising: a gallium and nitrogen containing substrate having a surface region configured in a non-polar orientation, an active region comprising a plurality of quantum well regions and at least a pair of thin barrier regions configured respectively on sides of at least one of the plurality of quantum well regions; wherein a gallium and nitrogen containing substrate member having an m-plane nonpolar crystalline surface region characterized by an off-cut orientation; a laser stripe region formed overlying a portion of the m-plane nonpolar crystalline orientation surface region, the laser stripe region being characterized by a cavity orientation substantially parallel to the c-direction, the laser stripe region having a first end and a second end; wherein each of the thin barrier regions is characterized by a thickness of 2.5 nm and less.
58. The laser device of claim 57 wherein each of the thin barrier regions is characterized by a thickness from 1.5 nm to 2.5 nm; and wherein the non-polar orientation is off-cut.