SiO₂/Gd₂O₃/GaN Metal Oxide Semiconductor Field Effect Transistors

GaN-based metal oxide semiconductor field effect transistors (MOSFETs) were demonstrated using a stacked gate oxide consisting of single-crystal Gd₂O₃ and amorphous SiO₂. Gd₂O₃ provides a good oxide/semiconductor interface and SiO₂ reduces the gate leakage current and enhances oxide breakdown voltage. Charge modulation of the n-channel depletion mode MOSFET was achieved for gate voltage from +2 to -4 V. The source-drain breakdown voltage exceeded 80 V. An intrinsic transconductance of 61 mS/mm was obtained at a gate-source and drain-source bias of -0.5 and 20 V, respectively. This is the first demonstration of epitaxial Gd₂O₃ growth on GaN and the first use of Gd₂O₃ as an insulating layer for nitride electronic device applications.