Novel antimonene tunneling field-effect transistors using an abrupt transition from semiconductor to metal in monolayer and multilayer antimonene heterostructures†
Recently, a mono-elemental two-dimensional (2-D) material, namely antimonene, with a large band gap, decent mobility and ambient stability has been extensively researched. Interestingly, although antimonene is a semiconductor with a sizable band gap in the monolayer, it is transformed to a metal in the multilayer. Inspired by this thickness dependent semiconductor to metal transition, we propose novel antimonene tunneling field-effect transistors (TFETs) based on the lateral monolayer (semiconducting)/multilayer (metallic)/monolayer (semiconducting) heterostructure. Our antimonene TFETs consist of a semiconducting monolayer source, channel and a drain and a small metallic multilayer region between the source and the channel. The local multilayer region introduces gapless metallic states which dramatically enhance the tunneling probability and hence result in a large current. To investigate the effect of a metallic multilayer on device performances, we carried out ab-initio electronic structure and quantum transport calculations for several antimonene TFETs based on different monolayer/multilayer/monolayer heterostructures. Simulation shows that even ∼1 nm scale nanostructured multilayer significantly boosts the current and enables abrupt device switching. More extensive evaluation is performed through benchmarking with phosphorene TFETs which have been identified as the best 2-D material based TFETs so far. In terms of the main figures of merit for FETs such as the intrinsic delay time and the power delay product, antimonene heterostructure TFETs outperform phosphorene TFETs, primarily due to the elimination of the tunneling barrier by the locally constructed multilayer antimonene.