Patent ID: 8431936

Claim:
A semiconductor light-emitting device, comprising: a layer of substrate material selected from a group consisting of Al 2 O 3 , Si, and SiC; a layer of n-type nitride material; an active-region layer; a first p-type layer consisting of doped GaN situated above the active-region layer, wherein the first p-type layer has a first acceptor density and a low lattice mismatch with the active-region layer; a second p-type layer consisting of doped GaN situated above and in direct contact with the first p-type layer, wherein the second p-type layer is thicker than the first p-type layer, wherein a thickness of the second p-type layer is greater than 100 nm, and wherein the second p-type layer has a second acceptor density; a third p-type layer consisting of doped GaN situated above and in direct contact with the second p-type layer, wherein the third p-type layer is thinner than the second p-type layer, wherein the third p-type layer has a third acceptor density, and wherein the third acceptor density is substantially the same as the first acceptor density; and an ohmic-contact layer situated above the third p-type layer.