Patent ID: 7038253

Claim:
A GaN-based field effect transistor comprising: a source electrode and a drain electrode; a channel portion made of a first GaN-based semiconducting material that is an i-GaN-based semiconducting material or a p-GaN-based semiconducting material, the channel portion being so formed as to be electrically connected to said source and drain electrodes; first and second electron supply portions made of second GaN-based semiconducting material having greater bandgap energy than said first GaN-based semiconducting material, the first and second electron supply portions being joined to said channel portion and located separately from each other; contact layers made of a third GaN-based semiconducting material having bandgap energy smaller than or equal to said first GaN-based semiconducting material, said contacting layers being located between said channel portion and the source electrode and between said channel portion and the drain electrode, respectively; an insulating layer overlaid on a surface of said channel portion, which spreads between said first and second electron supply portions; and a gate electrode disposed on said insulating layer.