| 主权项 |
1. A sapphire substrate having a principal surface on which a nitride semiconductor is growable to form a nitride semiconductor light emitting device, the sapphire substrate comprising a plurality of projections on the principal surface,
wherein each of the projections has a generally triangular pyramidal shape with a substantially sharpened tip and an inclined surface, the inclined surface being composed of a crystal growth-suppression surface that lessens the growth of the nitride semiconductor in comparison with a substrate surface located between adjacent projections, the inclined surface having an inclination change line at which an inclination angle discontinuously varies, wherein said plurality of projections are arranged to form a triangular lattice, and a direction of each of said plurality of projections conforms with a direction that is rotated by about 30 degrees from a direction of a triangle of the triangular lattice, and wherein an upper part of each of said projections above said inclination change line, which includes said substantially sharpened tip, has a height that is smaller than a height of a lower part of each of said projection below said inclination change line. |
