Charge trapping at the MoS₂-SiO₂ interface and its effects on the characteristics of MoS₂ metal-oxide-semiconductor field effect transistors

The field effect transistors (FETs) based on thin layer MoS₂ often have large hysteresis and unstable threshold voltage in their transfer curves, mainly due to the charge trapping at the oxide-semiconductor interface. In this paper, the charge trapping and de-trapping processes at the SiO₂-MoS₂ interface are studied. The trapping charge density and time constant at different temperatures are extracted. Making use of the trapped charges, the threshold voltage of the MoS₂ based metal-oxide-semiconductor FETs is adjusted from 4 V to -45 V. Furthermore, the impact of the trapped charges on the carrier transport is evaluated. The trapped charges are suggested to give rise to the unscreened Coulomb scattering and/or the variable range hopping in the carrier transport of the MoS₂ sheet.