Control of P-contact resistance in a semiconductor light emitting device
View Patent ↗A device according to embodiments of the invention includes a semiconductor structure including a light emitting layer disposed between an n-type region and a p-type region. A surface of the p-type region perpendicular to a growth direction of the semiconductor structure includes a first portion and a second portion. The first portion is less conductive than the second portion. The device further includes a p-contact formed on the p-type region. The p-contact includes a reflector and a blocking material. The blocking material is disposed over the first portion and no blocking material is disposed over the second portion.
1. A method comprising:
partially activating a p-type region in a group III-nitride structure comprising a light emitting layer disposed between an n-type region and the p-type region;
after partially activating the p-type region, forming a metal p-contact on the p-type region, the metal p-contact comprising:
a reflective first metal;
a second metal; and
a blocking material disposed over a first portion of the p-type region and no blocking material is disposed over a second portion of the p-type region; and
after forming the metal p-contact, further activating the p-type region such that the first portion is less conductive than the second portion.
2. The method of claim 1 wherein partially activating and further activating comprise annealing.
3. The method of claim 1 wherein partially activating and further activating comprise removing hydrogen from the p-type region.
4. The method of claim 3 wherein forming a metal p-contact comprises forming the second metal such that:
a first portion of the p-type region is covered by the second metal and a second portion of the p-type region is not covered by the second metal; and
the second metal prevents hydrogen from being removed from the first portion.
5. The method of claim 3 wherein forming a metal p-contact comprises forming the second metal such that the second metal prevents material disposed beneath the second metal from being oxidized.
6. The method of claim 1 wherein the first metal forms an Ohmic contact with the p-type region.
7. The method of claim 1 wherein the second metal getters hydrogen.
8. The method of claim 1 wherein the second metal is disposed within the first metal.
9. The method of claim 8 wherein the metal p-contact further comprises a third metal, wherein the first and second metals are disposed between the third metal and the p-type region.
10. The method of claim 9 wherein the third metal prevents material disposed beneath the third metal from being oxidized.
11. The method of claim 1 further comprising:
growing III-nitride semiconductor structure on a growth substrate;
removing the growth substrate; and
texturing a surface of the semiconductor structure exposed by removing the growth substrate.