NORMALLY-OFF HETEROJUNCTION FIELD-EFFECT TRANSISTOR

摘要

This normally-off HFET comprises: an undoped AlxGa1-xN layer (11) with thickness t1; a source electrode (21) and drain electrode (22) formed to be electrically connected to this layer (11) and separated from each other; an undoped AlyGa1-yN layer (12) with thickness t2 formed on the AlxGa1-xN layer between this source electrode and drain electrode; an undoped AlzGa1-zN layer (13) with thickness t3 formed in a mesa form in a partial region on the AlyGa1-yN layer between the source electrode and drain electrode; and a Schottky barrier type gate electrode (23) formed on the AlzGa1-zN layer. The conditions of y > x > z and t1 > t3 > t2 are satisfied.