Fabrication of AlGaN/GaN MIS‐HFET using an Al ₂ O ₃ high <i>k</i> dielectric

Abstract

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 μm with 15 μm 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 Vgs = −20 V which is at least three orders of magnitude lower than that of conventional AlGaN/GaN HFETs. (© 2003 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)