Patent ID: 8653502

Claim:
A Group III nitride semiconductor light-emitting device, comprising: a sapphire substrate; and a layered structure comprising a light-emitting layer provided on the sapphire substrate and including a Group III nitride semiconductor, wherein the sapphire substrate comprises a periodic structure on a surface on a side with the layered structure, wherein the periodic structure comprises at least one of dents and mesas arranged in a two-dimensional periodic array with a period which provides a dense honeycomb structure, in which a distance from any one of the dents or mesas to each of six adjacent dents or mesas is equal, and the periodic structure generates a light intensity interference pattern with a six-fold rotational symmetry for light emitted from the light-emitting layer, and wherein the period is from 2.25 μm to 3.25 μm, the periodic structure has a height of 0.5 μm to 2 μm, a side surface angle between a side wall and a base of one of the dents or mesas is 45° to 75°, a relative light intensity falls within a range of 1 to 0.9 when an emission angle of light emitted from the light-emitting device falls within a range of −45° to 45°.