Nitride-based metal-insulator- semiconductor capacitors with liquid-phase deposition oxide and (NH_4)_3S_x pretreatment prepared on sapphire substrates

摘要

Nitride-based metal-insulator-semiconductor (MIS) capacitors with liquid-phase deposition (LPD) oxide and (NH_4)_2S_x pretreatment were successfully prepared on sapphire substrates. It was found that we can significantly reduce the leakage current densities of the fabricated Al/LPD-SiO_2/AlGaN MIS capacitors by using (NH_4)_2S_x treatment. Compared to the MIS capacitors without (NH_4)_2S_x treatment, the leakage current densities were remarkably reduced by two orders of magnitude in (NH_4)_2S_x-treated MIS capacitors. Capacitance-voltage measurement showed that the MIS capacitor without (NH_4)_2S_x treatment was rather leaky. In contrast, the flat-band voltage shift, fixed oxide charge density and interface trap density of the fabricated MIS capacitor with (NH_4)_2S_x treatment were much improved to be 2.01 V, 7.22 × 10~(11) cm~(-2) and 7.19 × 10~(11) cm~2 eV~(-1), respectively. A related mechanism of (NH_4)_2S_x treatment was discussed by an x-ray photoelectron spectrometer