Patent ID: 7994539

Claim:
A light emitting diode, comprising: a substrate; a first conductive semiconductor 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, wherein the composition ratio of Al decreases in a declined stepwise manner, wherein the first region of the Al x Ga 1−x N buffer layer comprises alternating declining portions having a decreasing composition ratio of Al and constant portions having a constant composition ratio of Al, wherein a composition ratio of Al of a first constant portion and a composition ratio of Al of a second constant portion have a difference of 0.2, wherein the second constant portion is the step after the first constant portion in the declined stepwise decrease, and wherein the declining portions and constant portions are of comparable thicknesses.