CONTROL OF P-CONTACT RESISTANCE IN A SEMICONDUCTOR LIGHT EMITTING DEVICE
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 the p-type region in a III-nitride structure comprising a light emitting layer disposed between an n-type region and a 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; and
a second metal; and
after forming the metal p-contact, further activating the p-type region.
2 . The method of claim 1 , wherein the first metal is disposed between the second metal and the p-type region.
3 . The method of claim 2 , wherein the metal p-contact further comprises a third metal and the first and second metals are disposed between the third metal and the p-type region.
4 . The method of claim 3 , wherein the third metal is disposed above a first portion of the p-type region that is of lower conductivity.
5 . The method of claim 3 , wherein the third metal prevents material disposed beneath the third metal from being oxidized.
6 . The method of claim 3 , further comprising removing the second metal and the third metal by selective etch.
7 . The method of claim 1 , wherein the first metal is embedded in the second metal.
8 . The method of claim 7 , wherein the metal p-contact further comprises a third metal and the first and second metals are disposed between the third metal and the p-type region.
9 . The method of claim 8 , wherein the third metal is disposed above a first portion of the p-type region that is of lower conductivity.
10 . The method of claim 8 , wherein the third metal prevents material disposed beneath the third metal from being oxidized.
11 . The method of claim 8 , further comprising removing the third metal by selective etch.
12 . A device comprising:
a semiconductor structure comprising a light emitting layer disposed between an n-type region and a p-type region, wherein a surface of the p-type region comprises a first portion and a second portion, wherein the surface is perpendicular to a growth direction of the semiconductor structure, wherein the first portion is less conductive than the second portion; and
a p-contact formed on the p-type region, the p-contact comprising:
a reflective first metal; and
a second metal,
the first metal being embedded in the second metal.
13 . The device of claim 12 , wherein the metal p-contact further comprises a third metal and the first and second metals are disposed between the third metal and the p-type region.
14 . The device of claim 13 , wherein the third metal is disposed above a first portion of the p-type region that is of lower conductivity.
15 . A device comprising:
a semiconductor structure comprising a light emitting layer disposed between an n-type region and a p-type region, wherein a surface of the p-type region comprises a first portion and a second portion, wherein the surface is perpendicular to a growth direction of the semiconductor structure, wherein the first portion is less conductive than the second portion; and
a p-contact formed on the p-type region, the p-contact comprising:
a reflective first metal; and
a second metal,
the first metal being disposed between the second metal and the p-type region.
16 . The device of claim 15 , wherein the metal p-contact further comprises a third metal and the first and second metals are disposed between the third metal and the p-type region.
17 . The device of claim 16 , wherein the third metal is disposed above a first portion of the p-type region that is of lower conductivity.