AlN/AlGaN/GaN MIS-HEMTs with recessed source/drain ohmic contact

AlN/AlGaN/GaN MIS-HENITs were grown on 4 inch silicon to suppress the gate leakage and achieve high breakdown, However the drain current density maximum obtained is low (361 mA/mm) for 15 mu m MIS-HEMTs. Since the contact resistance of the Ohmic contacts on the insulating AlN is high (5.1 Omega mm), the thin AlN layer was etched prior to the evaporation of the source-drain Ohmic contact. Though the recessed Ohmic contact reduced the contact resistance to 2.5 Omega mm there is no improvement in the drain current density. The poor quality of the 2 nm AlN growth on silicon could be the possible reason behind the low drain current density. (C) 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.