Patent ID: 8664693

Claim:
A light emitting diode, comprising: a substrate; a first conductive semiconductor layer comprising an N-type Al z In y Ga 1-z-y N (0≦z,y,z+y≦1) layer positioned on the substrate; and an Al x Ga 1-x N (0≦x≦1) buffer layer interposed between the substrate and the first conductive semiconductor layer and comprising a first region having a composition ratio x of Al decreasing from the substrate to the first conductive semiconductor layer and a second region of the Al x Ga 1-x N buffer layer having the composition ratio of Al equal to 1, wherein the second region contacts the first region and the substrate, wherein the second region has a thickness of about 1 nm to about 50 nm, wherein the first conductive semiconductor layer contacts the Al x Ga 1-x N buffer layer, and wherein the degree of lattice mismatch between the substrate and the second region of the Al x Ga 1-x N buffer layer is smaller than the degree of lattice mismatch between the substrate and the first conductive semiconductor layer.