Epitaxial substrate for semiconductor device, semiconductor device, and method of manufacturing epitaxial substrate for semiconductor device

摘要

Provided is an epitaxial substrate capable of achieving a semiconductor device that has excellent ohmic contact characteristics as well as satisfactory device characteristics. On a base substrate, a channel layer formed of a first group III nitride that contains at least Al and Ga and has a composition of Inx1Aly1Gaz1N (x1+y1+z1=1) is formed. On the channel layer, a barrier layer formed of a second group III nitride that contains at least In and Al and has a composition of Inx2Aly2Gaz2N (x2+y2+z2=1) is formed such that an In composition ratio of a near-surface portion is larger than an In composition ratio of a portion other than the near-surface portion.