PURPOSE: To enhance the mobility of electrons flowing through a channel layer by the uniform formation of the hetero interface along the channel layer on the basis of an atomic measure by a method wherein the interface is formed only by two-element compound of GaAs and AlAs.

CONSTITUTION: A non-doped GaAs layer 2 is formed on a semi-insulation GaAs substrate 1. Using a non-doped AlAs layer 16 as the layer forming the hetero interface between the GaAs layer 2, the interface 17 is formed. Further, an N type AlGaAs layer, an N type GaAs layer 5, a gate electrode 5, a source electrode 7, and a drain electrode 8 are provided.