Patent ID: 7470938

Claim:
A nitride semiconductor light emitting device comprising: a substrate having upper and lower surfaces; a n-type nitride semiconductor layer formed on the upper surface of the substrate; an active layer formed on the upper surface of the n-type nitride semiconductor layer such that the n-type nitride semiconductor layer is partially exposed; a p-type nitride semiconductor layer formed on the upper surface of the active layer; a p-electrode formed on an upper surface of the p-type nitride semiconductor layer; and a n-side electrode formed on the partially exposed n-type nitride semiconductor layer; wherein the lower surface of the substrate comprises a regular pattern of hemispherical cavities for reducing total internal reflection at an interface between said lower surface of the substrate and an environment outside said device; and wherein the upper surface of the substrate comprises a regular pattern of hemispherical raised projections for reducing total internal reflection at an interface between said upper surface of the substrate and the n-type nitride semiconductor layer formed thereon.