Role of induced-strain and interlayer coupling in contact resistance of VS2–BGaX2 (X = S, Se) van der Waals heterostructures

Abstract

Using Density Functional Theory (DFT) calculations, we explored the electronic band structure and contact type (Schottky and Ohmic) at the interface of VS₂–BGaX₂ (X = S, Se) metal–semiconductor (MS) van der Waals heterostructures (vdWHs). The thermal and dynamical stabilities of the investigated systems were systematically validated using energy–strain analysis, ab initio molecular dynamics (AIMD) simulations, as well as binding energy and phonon spectrum calculations. After analyzing the band structure, VS₂–BGaX₂ (X = S, Se) MS vdWHs metallic behavior with type-III band alignment is revealed. A p-type Schottky (Ohmic) contact in VS₂–BGaS₂ (VS₂–BGaSe₂) MS vdWHs with decreasing (increasing) tunneling probabilities (current) shows its potential uses in phototransistors, photodetectors and high-speed nanoelectronic devices. Additionally, the work function (ϕ), electrostatic potential and charge density difference are also investigated to gain detailed insights into the work function variations and charge transfer between layers during the fabrication of VS₂–BGaX₂ (X = S, Se) MS vdWHs. At equilibrium interlayer distance, strong interlayer coupling due to the vdW interactions is further confirmed via Bader charge analysis, showing that the electrons are transferred from BGaS₂(VS₂) to the VS₂(BGaS₂) layer in VS₂–BGaS₂ (VS₂–BGaSe₂) MS vdWHs. These calculations give a new strategy for experimentalists to design advanced high-speed nanoelectronic devices based on VS₂–BGaX₂ (X = S, Se) MS vdWHs.