Role of induced-strain and interlayer coupling in contact resistance of VS ₂ –BGaX ₂ (X = S, Se) van der Waals heterostructures

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, <i>ab initio</i> 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 (<i>ϕ</i>), 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 <i>via</i> 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.