Revealing space-charge capacitance in multi-layer dielectrics with Sb2O3/MoS2/SiO2

Antimony trioxide (Sb2O3) has recently attracted attention as a top-gate dielectric for two-dimensional transition metal dichalcogenide materials due to its high permittivity and van der Waals gap, which contribute to minimal mobility degradation. In this study, the MIS dielectric behavior of Au/Al/Sb2O3/SiO2/P++Si capacitors was investigated under different alternating-current (AC) frequencies and direct-current (DC) bias voltages. The results demonstrated an exponential dependence of capacitance on the DC bias voltage, and a linear log–log relationship between the capacitance and the reciprocal of AC frequency indicating a space-charge-dominated response. By comparing the extracted dielectric constants, we further confirmed that the capacitance magnitude is primarily governed by the Sb2O3 dielectric layer. In contrast, the Au/Al/Sb2O3/MoS2/SiO2/P++Si capacitor showed stronger bias dependence and frequency dispersion, which are attributed to the combined effects of MIS carrier accumulation and Maxwell–Wagner interfacial polarization in the multilayer stack. These findings provide useful insight into the design of tunable switches and adjustable circuit elements and may also contribute to improved breakdown reliability and longer device lifetime. Moreover, the device exhibits its potential applications in tunable switches and adjustable circuit elements. This insight may further assist in improving breakdown reliability and extending device lifetime.