Fabrication of AlGaN/GaN MIS-HFET using an Al2O3 high k dielectric

We report on a metal-insulator-semiconductor AlGaN/GaN heterostructure field-effect transistor (MIS-HFET) using Al2O3 simultaneously for channel passivation layer and as a gate insulator which was deposited by plasma enhanced atomic layer deposition(PE-ALD). Capacitance-voltage measurements show successful surface passivation by the Al2O3 dielectric layer. For a gate length 1.2 mum with 15 mum source-to-drain spacing the maximum drain current was 1.22 A/mm, the maximum transconductance was 166 mS/mm and the gate leakage current was 4 nA/mm at V-gs = -20 V which is at least three orders of magnitude lower than that of conventional AlGaN/GaN HFETs. (C) 2003 WILEY-VCH Verlag GmbH & Co. KGaA. Weinheim.