Patent ID: 8872226
Filing Date: 2014-10-28
Classification: C30B,H01L

Abstract:
1. An epitaxial substrate for a semiconductor device, comprising: a base substrate; a channel layer formed of a first group III nitride having a composition of In a barrier layer formed of a second group III nitride containing at least In and Al and having a composition of In the composition of said first group III nitride is in a range determined by x1=0 and 0≦y1≦0.3; and the composition of said second group III nitride is, in a ternary phase diagram with InN, AlN and GaN being vertices, in a range surrounded by straight lines respectively represented by the following expressions determined in accordance with the composition of said first group III nitride: the mean surface roughness at the interface between the channel layer and the barrier layer is within a range of 0.1 nm to 3 nm.