Unveiling Fast Interface Trap Dynamics in Monolayer MoS₂ FETs

Abstract

wo-dimensional materials like molybdenum disulfide (MoS2) are viable candidates for future ultra-scaled stacked nanosheet field-effect transistors. For current transistor prototypes based on 2D materials, a hysteresis in the transfer characteristics is often observed. Threshold voltage hysteresis in 2D FETs is typically ascribed to insulator traps. While fast interface traps are typically associated with changes in the subthreshold swing, here we show that they can also contribute to the hysteresis at low temperatures and fast operating frequencies. We employ the full quantum-mechanical non-radiative multi-phonon model to analyze trap-mediated charge transition in monolayer (1-L) MoS2 FETs at 300 K and 77 K. Simulating the trap responses over a wide range of parameters reveals that, depending on the trap properties, the charge transition is either thermally activated or dominated by nuclear tunneling. We further demonstrate that the hysteresis of thermally activated traps can shift into the measurement window at low temperatures.