SINGLE-CRYSTAL SUBSTRATE, GROUP III ELEMENT NITRIDE CRYSTAL OBTAINED USING SAME, AND PROCESS FOR PRODUICNG GROUP III ELEMENT NITRIDE CRYSTAL

摘要

Provided is a substrate on which a large-area thick crystal of a Group III element nitride can be grown while inhibiting cracking. The substrate is a single-crystal substrate for use in growing a Group III element nitride crystal thereon and satisfies relationship (1): -40 < Z2/Z1 < -1 (1) wherein Z1 is the amount of warpage (µm) of the physical shape of the growth surface of the single-crystal substrate and Z2 is the amount of warpage (µm) calculated from the radius of curvature of the crystallographic surface shape of the growth surface of the single crystal.