Patent ID: 8853828

Claim:
An epitaxial substrate for semiconductor device, in which a group of group-III nitride layers are formed on a base substrate of single-crystal silicon having a (111) orientation so that a (0001) crystal plane is approximately parallel to a surface of the base substrate, comprising: a first group-III nitride layer formed of AlN on said base substrate; a second group-III nitride layer formed of In xx Al yy Ga zz N (xx+yy+zz=1, 0≦xx<1, 0≦yy<1, and 0<zz≦1) on said first group-III nitride layer; and at least one third group-III nitride layer epitaxially-formed on said second group-III nitride layer, wherein: said first group-III nitride layer is a layer containing multiple defects including at least one type of a columnar crystal, a granular crystal, a columnar domain and a granular domain; and an interface between said first group-III nitride layer and said second group-III nitride layer is a three-dimensional asperity surface.