Patent ID: 8426893

Claim:
An epitaxial substrate for an electronic device, comprising: a conductive SiC single crystal substrate, a buffer as an insulating layer on the SiC single crystal substrate, and a main laminate formed by epitaxially growing a plurality of Group III nitride layers on the buffer, wherein a lateral direction is a current flow direction, the buffer includes at least an initial growth layer in contact with the SiC single crystal substrate and a superlattice laminate having a superlattice multi-layer structure on the initial growth layer, the initial growth layer is made of a B a1 Al b1 Ga c1 In d1 N (0≦a 1 ≦1, 0<b 1 ≦1, 0≦c 1 ≦1, 0≦d 1 ≦1, a 1 +b 1 +c 1 +d 1 =1) material, the superlattice laminate is configured by alternately stacking a first layer made of a B a2 Al b2 Ga c2 In d2 N (0≦a 2 ≦1, 0≦b 2 ≦1, 0≦c 2 ≦1, 0≦d 2 ≦1, a 2 +b 2 +c 2 +d 2 =1) material and a second layer made of a B 3 Al b3 Ga c3 In d3 N (0≦a 3 ≦1, 0≦b 3 ≦1, 0≦c 3 ≦1, 0≦d 3 ≦1, a 3 +b 3 +c 3 +d 3 =1) material having a different band gap from the first layer, and at least one of the superlattice laminate and a portion of the main laminate on the buffer side has a C concentration of 1×10 18 /cm 3 or more.