PROCESS FOR PRODUCING AN EPITAXIAL SUBSTRATE FOR A SEMICONDUCTOR ELEMENT

摘要

Provided is an epitaxial substrate having excellent two-dimensional electron gas characteristics and reduced internal stress due to strains. A channel layer is formed of a first group III nitride represented by In x1 Al y1 Ga z1 N (x1+y1+z1=1) so as to have a composition in a range determined by x1=0 and 0‰¤y1‰¤0.3. A barrier layer is formed of a second group III nitride represented by In x2 Al y2 Ga z2 N (x2+y2+z2=1) so as to have a composition, in a ternary phase diagram with InN, AlN and GaN being vertices, in a range surrounded by five straight lines determined in accordance with the composition (AlN molar fraction) of the first group III nitride.