Physical and electrical characteristics of AlGaN/GaN metal-oxide- semiconductor high-electron-mobility transistors with rare earth Er ₂O₃ as a gate dielectric

In this study, the rare earth erbium oxide (Er₂O₃) was deposited using an electron beam onto an AlGaN/GaN heterostructure to fabricate metal-oxide-semiconductor high-electron-mobility transistors (MOS-HEMTs) that exhibited device performance superior to that of a conventional HEMT. Under similar bias conditions, the gate leakage currents of these MOS-HEMT devices were four orders of magnitude lower than those of conventional Schottky gate HEMTs. The measured sub-threshold swing (SS) and the effective trap state density (N_t) of the MOS-HEMT were 125 mV/decade and 4.3×10¹² cm^-2, respectively. The dielectric constant of the Er₂O₃ layer in this study was 14, as determined through capacitance-voltage measurements. In addition, the gate-source reverse breakdown voltage increased from -166 V for the conventional HEMT to -196 V for the Er₂O₃ MOS-HEMT.