NONPOLAR OR SEMIPOLAR GaN SUBSTRATE

摘要

PROBLEM TO BE SOLVED: To provide a disk type nonpolar or semipolar GaN substrate which has excellent in-plane uniformity in temperature when heated through a susceptor.SOLUTION: There is provided a disk type nonpolar or semipolar GaN substrate 10 whose top surface 11 is not a concave surface even at room temperature. The GaN substrate 10 is such that: the top surface 11 may be a convex surface at room temperature and has a diameter of 4.5-5.5 cm; an SORI value of the top surface 11 at room temperature is 20 μm or less, (the SORI value being an index for quantizing a degree of warpage of the substrate and a value obtained by totaling a distance between a highest point on the top surface and a reference surface and a distance between a lowest point the top surface and the reference surface, where the reference surface is a least square plane of the top surface of the substrate); and the angle between a normal to the top surface 11 and an "m" axis is 0-20° or less. The semipolar GaN substrate 10 is a GaN substrate 10 made of GaN crystal of less than 1×10cmin alkali metal concentration and 2 cmor less in absorption coefficient at 450 nm.SELECTED DRAWING: Figure 1