Patent ID: 8410472

Claim:
An epitaxial substrate for an electronic device comprising a Si single crystal substrate, a buffer as an insulating layer formed on the Si single crystal substrate, and a main laminated body formed by plural group III nitride layers epitaxially grown on the buffer, wherein a lateral direction of the epitaxial substrate is defined as an electric current conducting direction, wherein: the buffer includes at least an initially grown layer in contact with the Si single crystal substrate and a superlattice laminate constituted of a superlattice multilayer structure on the initially grown layer; the initially grown layer is made of an AlN material; the superlattice laminate is formed by alternate lamination of a first layer 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 and a second 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 having a band gap different from that of the first layer; and both of the superlattice laminate and a portion, on the buffer side, of the main laminated body has carbon concentration of 1×10 18 /cm 3 or higher.