CPC C30B 25/20 (2013.01) [C30B 25/08 (2013.01); C30B 25/10 (2013.01); C30B 29/406 (2013.01)] | 3 Claims |
1. A crystal substrate which is a substrate consisting of a single crystal of group III nitride, having a diameter of 4 inches or more, and in which c-plane of the single crystal is curved in a concave spherical shape toward inside of the substrate, when a main surface of the substrate is viewed from +c side with a radius of curvature of 15 m or more, the c-plane of the single crystal has a constant radius of curvature in a region of 80% or more of an area of the main surface viewed in plan view, and the substrate consists of a single domain,
wherein a thickness of the substrate is 0.2 mm or more, and
wherein the radius of curvature of the c-plane of the single crystal in a-axis direction is 27.2 m or more and the radius of curvature of the c-plane of the single crystal in m-axis direction is 35.6 m or more.
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