Patent ID: 8039329

Claim:
A method for fabricating a field effect transistor comprising the steps of: (a) successively forming, on a substrate, a first nitride semiconductor layer, a second nitride semiconductor layer having a wider band gap than said first nitride semiconductor layer and a capping layer made of a compound represented by a general formula of In x Al y Ga 1−y N (wherein 0<x≦1, 0≦y<1 and 0<x+y≦1); (b) forming a source electrode and a drain electrode on said capping layer to be spaced from each other; after step (a) and before step (b), a step (c) of forming an opening in said capping layer for exposing said second nitride semiconductor layer therein; and after step (c) and before step (b), a step (d) of forming an insulating film at least on the portion of said second nitride semiconductor layer exposed in said opening, wherein said source electrode and said drain electrode are formed without performing annealing in the step (b), and step (b) includes a sub-step of forming a gate electrode on a portion of said second nitride semiconductor layer exposed in said opening.