Patent ID: 8330167

Claim:
A GaN-based field effect transistor, comprising: a substrate; a channel layer comprised of p-type or undoped GaN-based semiconductor material formed on the substrate; an electron supplying layer formed on said channel layer and comprised of GaN-based semiconductor material which has a band gap energy greater than that of said channel layer; a first insulating film formed on a surface of said channel layer which was exposed after a part of said electron supplying layer was removed; a gate electrode formed on said first insulating film; a source electrode and a drain electrode formed so that said gate electrode positions in between them; and a second insulating film formed on said electron supplying layer, which is a different insulating film from said first insulating film and has an electron collapse decreasing effect, wherein a side surface of the second insulating film between the gate electrode and the drain electrode, which has a contact with the first insulating film, is formed in a different plane from a side surface of the electron supplying layer.