Nitride-based metal-insulator-semiconductor capacitors with liquid-phase deposition oxide and (NH₄)₂S_x pretreatment prepared on sapphire substrates

Nitride-based metal-insulator-semiconductor (MIS) capacitors with liquid-phase deposition (LPD) oxide and (NH₄)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-SiO₂/AlGaN MIS capacitors by using (NH ₄)₂S_x treatment. Compared to the MIS capacitors without (NH₄)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 (NH₄)₂S _x treatment were much improved to be 2.01 V, 7.22 × 10 ¹¹ cm^-2 and 7.19 × 10¹¹ cm^-2 eV^-1, respectively. A related mechanism of (NH₄) ₂S_x treatment was discussed by an x-ray photoelectron spectrometer