Theoretical Investigation of Dielectric Materials for Two-Dimensional Field-Effect Transistors

Two-dimensional dielectric materials that can inhibit electronic leakage are vital for developing next-generation all-2D electronic devices. However, few comprehensive studies of the atomistic nature of 2D insulating dielectrics currently exist. In this work, computational design strategies based on density functional theory and quantum dynamics simulations are used to assess the charge permeability through dielectric materials. Promising 2D dielectrics are considered, including monolayer SiC, hBN, and BeO, which possess promising properties and a honeycomb structure compatible with that of MoS2, currently the most commonly used channel material in all-2D transistors. A useful protocol for discovering promising dielectrics is described. The atomic structures of the interfaces are determined and their stabilities are evaluated by studying the interface formation energies and the presence of stress/strain at the interfaces. The interface electronic structures are characterized by studying the band structures, band offsets, and charge transfer at the interface. These important quantities reveal that all three materials chosen are good dielectric materials, but SiC is the poorest among them, BeO has the best insulting properties as a monolayer and hBN prevents the most charge leakage at the interface. It is shown how this protocol can also consider the effects of external potentials and temperatures.