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

Abstract

Nitride-based metal–insulator–semiconductor (MIS) capacitors with liquid-phase deposition (LPD) oxide and (NH4)2Sx 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 (NH4)2Sx treatment. Compared to the MIS capacitors without (NH4)2Sx treatment, the leakage current densities were remarkably reduced by two orders of magnitude in (NH4)2Sx-treated MIS capacitors. Capacitance–voltage measurement showed that the MIS capacitor without (NH4)2Sx 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)2Sx treatment were much improved to be 2.01 V, 7.22 × 1011 cm−2 and 7.19 × 1011 cm−2 eV−1, respectively. A related mechanism of (NH4)2Sx treatment was discussed by an x-ray photoelectron spectrometer