Effects of high-k dielectric environment on the full ballistic transport properties of monolayer MoS2 FETs

Abstract

High-k dielectric materials are indispensable as gate layers for micro- and nano-electronic devices. Using first-principles calculations and non-equilibrium Green's function simulations, we studied the electrical transport characteristics of p-type and n-type monolayer MoS2 field effect transistors (FETs) under various gate dielectric environments. We found that the intrinsic dielectric property of the gate insulator played an important role in the transport performance of nanodevices. For both types of MoS2 FETs, a high-k gate insulator enhances the current on/off ratio and reduces the subthreshold swing by properly shifting the valence (p-type) or conduction (n-type) bands around the bias energy window, which has benefits for the design of MoS2-based short-channel nanodevices in the future.

Modeling the Impact of Phonon Scattering with Strain Effects on the Electrical Properties of MoS2 Field-Effect Transistors

“…Conversely, the on–off ratio demonstrates an increasing trend with high-k dielectrics. This can be attributed to the shifting of the valence and conduction bands [ 61 ] and the enhancement of the fringing electric field within the device. These factors contribute to a higher on current and a lower off current, ultimately resulting in an improved on–off ratio [ 62 ].…”

“…Conversely, the on-off ratio demonstrates an increasing trend with high-k dielectrics. This can be attributed to the shifting of the valence and conduction bands [61] and the enhancement of the fringing electric field within the device. These factors contribute to a higher on current and a lower off current, ultimately resulting in an improved on-off ratio Therefore, the utilization of high-k dielectrics is preferable in devices with shorter channel lengths because it increases the off current caused by the reduced distance between the source and drain, thereby enhancing the punch-through effect [63].…”