AlGaN/GaN heterostructure field effect transistor (HFET) with the room-temperature ohmic contact (1.0 x 10(-4) Omegacm(2)) was demonstrated through the surface treatment using N-2 inductively coupled plasma. The N-2 plasma produced N vacancies on the surface of undoped AlGaN, leading to ohmic contact at as-deposited state, The fabricated HFET exhibited the saturation drain current density of 736 mA/mm and transconductance of 148 mS/mm. This room-temperature ohmic contact was suitable for fabrication of AlGaN/GaN HFET. (C) 2002 Elsevier Science Ltd. All rights reserved.