Patent ID: 8692261

Claim:
A device comprising: a first semiconductor layer, wherein the first semiconductor layer is a III-nitride layer; a second semiconductor layer; a third semiconductor layer; and a semiconductor structure comprising a III-nitride light emitting layer disposed between an n-type region and a p-type region; wherein the second semiconductor layer is disposed between the first semiconductor layer and the third semiconductor layer; the third semiconductor layer is disposed between the second semiconductor layer and the light emitting layer, and the third semiconductor layer is a continuous layer of uniform composition that is as wide as the second semiconductor layer; a difference between an in-plane lattice constant of the first semiconductor layer and a bulk lattice constant of the third semiconductor layer is no more than 1%; a difference between an in-plane lattice constant of the first semiconductor layer and a bulk lattice constant of the second semiconductor layer is at least 1%; and the second semiconductor layer and the third semiconductor layer are at least partially relaxed.