Patent ID: 7012286

Claim:
A heterojunction field effect transistor having a one-step gate recess structure comprising: a gate electrode; a barrier layer; a recess adjacent the gate electrode; and a contact layer, wherein eye-empty areas extend in a lateral direction of the gate electrode from opposing first and second sides of the gate electrode to an upper end of a side wall of the recess, and also extend in a transverse direction of the gate electrode from a low end of the gate electrode to an upper end of the contact layer, the eye-empty areas being formed by at least three material layers having different impurity concentrations, the gate electrode being formed on the barrier layer and a part of the gate electrode being attached to a part of the eye-empty areas and wherein the at least three material layers forming the eye-empty areas have a plurality of corner portions centralizing electric fields which are formed by using a low impurity concentration layer or a non-doped layer.