Monte Carlo study of carrier transport in two-dimensional transition metal dichalcogenides: high-field characteristics and MOSFET simulation

Abstract

Field-effect transistors (FETs) having two-dimensional (2D) materials as the channel offer superior gate control and decreased short-channel effects when compared to bulk-semiconductor channels. Here, employing ab initio band structure and scattering rates as input to Monte Carlo simulations, we investigate the electron-transport characteristics in monolayer MoS2 and WSe2 at high fields and simulate double-gate MOSFETs based on these TMD materials. Considering different gate insulators and TMD channels, we also account for the effects caused by the dielectric environment (substrate and gate insulators, and metal-gate contact) on the transport properties of the 2D channel and on the transfer characteristics of the devices. In all cases, the saturation velocity at high fields and the on-current and transconductance of the devices are significantly depressed by these 'dielectric environment' effects. In particular, accounting fully for the presence of the dielectrics, in the double-gate nMOS device with MoS2 as the channel, the Ion calculated is approximate to 380 mu A/mu m for the more realistic gate stack of HfO2/MoS2/SiO2, which is in the borderline of fulfilling the demands of the International Technology Roadmap for Semiconductors (ITRS) and the International Roadmap for Devices and Systems (IRDS) for low power applications. However, in the double-gate pMOS device with WSe2 as the channel, the on-current calculated is approximate to 800 mu A/mu m for the HfO2/WSe2/SiO2 system, which satisfies the ITRS requirements.