Heterojunction field effect transistor

摘要

A heterojunction field effect transistor includes a carrier supplying layer comprising material which is not likely to produce a deep level even by doping. A channel layer comprises material which has the largest electron affinity among three types of semiconductor material constituting the heterojunction FET and has a high carrier mobility. A spacer layer is interposed between the channel layer and the carrier supplying layer and comprises material which enables the reduction of Coulomb interaction between two-dimensional carriers in the channel layer and ions in the carrier supplying layer. In addition, the spacer layer increases the effective conduction band energy discontinuity DELTA Ec between the carrier supplying layer and the channel layer.