High electron mobility transistor

Abstract

A semiconductor device comprises a substrate, a channel layer provided on the substrate and formed of an undoped first semiconductor material containing indium arsenide, a two-dimensional electron gas formed in the channel layer as a substantially scatter-free path of electrons, an electron supplying layer provided on the channel layer to form a heterojunction interface with the channel layer, a source electrode provided on the electron supplying layer for injecting electrons, a drain electrode provided on the electron supplying layer for collecting electrons and a gate electrode provided on the electron supplying layer for controlling the passage of the electrons in the two-dimensional electron gas. The electron supplying layer comprises a second compound semiconductor material having a lattice constant matching to the channel layer and doped to the n-type to form the two-dimensional electron gas. The second compound semiconductor material has a valence band having an energy level higher than the conduction band of the channel layer at the heterojunction interface, and the second compound semiconductor material is doped to a concentration level such that the Fermi level is located between the valence band and the conduction band of the second compound semiconductor material forming the electron supplying layer.