Epitaxial substrate
There is provided an epitaxial substrate, including: a GaN substrate whose main surface is a c-plane; and a GaN layer epitaxially grown on the main surface, wherein the main surface includes a region where an off-angle is 0.4° or more, and an E3 trap concentration in the GaN layer grown on the region is 3.0×10 13 cm −3 or less.
1. An epitaxial substrate, comprising:
a GaN substrate whose main surface is a c-plane; and
a GaN layer epitaxially grown on the main surface,
wherein the main surface includes a region where an off-angle is 0.4° or more, and an E3 trap concentration in the GaN layer grown on the region is 3.0×10 13 cm −3 or less, and
wherein a carrier concentration in the GaN layer grown on the region increases with increasing the off-angle throughout a range of the off-angle of 0.4° to 1° and is 6×10 15 cm −3 or more and 1×10 16 cm −3 or less throughout the range of the off-angle of 0.4° to 1°.
2. The epitaxial substrate according to claim 1 ,
wherein in the GaN layer grown on the region, a ratio of a maximum E3 trap concentration to a minimum E3 trap concentration is 1.5 times or less.
3. The epitaxial substrate according to claim 1 , wherein a carbon concentration in the GaN layer grown on the region is 5×10 15 cm −3 or less.