Si Ion Implantation into Mg-Doped GaN for Fabrication of Reduced Surface Field Metal–Oxide–Semiconductor Field-Effect Transistors

Abstract

We have studied the activation of Si ion implanted un- and Mg-doped gallium nitride (GaN) for the fabrication of reduced surface field (RESURF) metal–oxide–semiconductor field-effect transistors (MOSFETs). By annealing at 1260 °C for 30 s by using rapid thermal annealing (RTA), the activation ratios of un- and Mg-doped GaN with Si doses of 3×1015 cm-2 were ∼100 and 73%, respectively. These values are sufficient for application some semiconductor devices. Hardly any diffusion of the Si atoms implanted in GaN was observed by secondary ion mass spectrometry (SIMS). The activation ratio between un- and Mg-doped GaN was markedly different at low doses. The cause of the difference appears to be Mg compensation in GaN. In addition, we fabricated GaN MOSFETs with ion implanted RESURF zones. We also monitored the field-effect transitor (FET) operation and high breakdown voltage of the GaN MOSFETs. The threshold voltage was +2 V. An enhancement mode operation and a breakdown voltage higher 1500 V at a RESURF length of 20 µm were achieved.