Compound semiconductor substrate

Abstract

The present invention provides a compound semiconductor substrate, including: a single-crystal silicon substrate having a crystal face with (111) orientation; a first buffer layer which is formed on the single-crystal silicon substrate and is constituted of an AlxGa1-xN single crystal (0<x≦1); a second buffer layer which is formed on the first buffer layer and is composed of a plurality of first unit layers each having a thickness of from 250 nm to 350 nm and constituted of an AlyGa1-yN single crystal (0≦y<0.1) and a plurality of second unit layers each having a thickness of from 5 nm to 20 nm and constituted of an AlzGa1-zN single crystal (0.9<z≦1), said pluralities of first and second unit layers having been alternately superposed; and a semiconductor device formation region which is formed on the second buffer layer and includes at least one nitride-based semiconductor single-crystal layer. The compound semiconductor substrate according to the invention is suitable for use in electronic devices such as HEMTs (high electron mobility transistors).

Dependencies are inferred from the claim text.