Patent ID: 8017973

Claim:
A nitride semiconductor light-emitting device comprising: a buffer layer on a substrate, wherein the buffer layer includes a plurality of layers having different lattice constants; a first n-type nitride semiconductor layer on the buffer layer; an active layer on the first n-type nitride semiconductor layer; a p-type nitride semiconductor layer on the active layer, wherein the buffer layer comprises: a first buffer layer on the substrate, wherein the first buffer layer has a larger lattice constant than the substrate; a second buffer layer on the first buffer layer, wherein the second buffer layer has a smaller lattice constant than the first buffer layer; and a third buffer layer on the second buffer layer, wherein the third buffer layer has a smaller lattice constant than the second buffer layer, wherein a difference of lattice constant between the third buffer layer and the first n-type nitride semiconductor layer is smaller than a difference of lattice constant between the second buffer layer and the n-type nitride semiconductor layer, and wherein the third buffer layer includes AIN, and wherein the substrate includes a sapphire substrate.