EPITAXIAL SUBSTRATE FOR SEMICONDUCTOR ELEMENT, SEMICONDUCTOR ELEMENT, PN JUNCTION DIODE, AND METHOD FOR MANUFACTURING AN EPITAXIAL SUBSTRATE FOR SEMICONDUCTOR ELEMENT

摘要

Provided is an epitaxial substrate for use in a semiconductor element, having excellent characteristics and capable of suitably suppressing diffusion of elements from a cap layer. An epitaxial substrate for use in a semiconductor element, in which a group of group-III nitride layers are laminated on a base substrate such that a (0001) crystal plane of the group of group-III nitride layers is substantially in parallel with a substrate surface of the base substrate, includes: a channel layer made of a first group-III nitride having a composition of Inx1Aly1Gaz1N (x1+y1+z1=1, z1>0); a barrier layer made of a second group-III nitride having a composition of Inx2Aly2N (x2+y2=1, x2>0, y2>0); an anti-diffusion layer made of AlN and having a thickness of 3 nm or more; and a cap layer made of a third group-III nitride having a composition of Inx3Aly3Gaz3N (x3+y3+z3=1, z3>0).