AlGaN-GaN Metal-Insulator-Semiconductor High-Electron-Mobility Transistors With Very High- $k$ Oxynitride $\hbox{TaO}_{x} \hbox{N}_{y}$ Gate Dielectric

We investigated AlGaN-GaN metal-insulator-semiconductor high-electron-mobility transistors (MIS-HEMTs) with high-permittivity (high-
$k$
) oxynitride
$\hbox{TaO}_{x}\hbox{N}_{y}$
gate dielectric
$(k \sim\!\hbox{24})$
obtained by sputtering deposition. The MIS-HEMTs show excellent pulsed current-voltage characteristics, small off-leakage currents
$(< \hbox{10}^{-10} \ \hbox{A/mm})$
, high on/off current ratios
$(> \hbox{10}^{10})$
, and favorable threshold voltage stabilities. From comparisons with MIS-HEMTs with
$\hbox{TaO}_{x}$
gate dielectric, we conclude that N incorporation in gate dielectric can suppress current collapse and deep-level states.