Role of induced-strain and interlayer coupling in contact resistance of VS$_2$-BGaX$_2$ (X=S, Se) van der Waals Heterostructure

Abstract

Using Density Functional Theory (DFT) calculations, electronic band structure and contact type (Schottky/Ohmic contact) at the interface of VS$_2$-BGaX$_2$ (X=S, Se) metal-semiconductor (MS) van der Waals heterostructures (vdWHs) are investigated. The stabilities of these systems is validated via energy-strain approach, ab-intio molecular dynamics (AIMD) simulations, along with binding energies and phonon spectrum calculations. After analyzing the band structure, VS$_2$-BGaX$_2$ (X=S, Se) MS vdWHs reveals metallic behavior with type-III band alignment. A p-type Schottky(Ohmic) contact in VS$_2$-BGaS$_2$(VS$_2$-BGaSe$_2$) MS vdWHs with lowering(increasing) the tunneling probabilities (current), show potential applications in phototransistor, photodetectors and high-speed nanoelectronic devices. Additionally, the workfunction ($\phi$), charge transfer across the layers, electrostatic potential, and charge density difference, are also investigated to gain a detailed insights into the work function variations and charge transfer between layers during the fabrication of VS$_2$-BGaX$_2$ (X=S, Se) MS vdWHs. At equilibrium interlayer distance, strong interlayer coupling due to the vdW interaction are further confirmed via Bader charge analysis, shows that the electron are transfer from BGaS$_2$(VS$_2$) to the VS$_2$(BGaS$_2$) layer in VS$_2$-BGaS$_2$(VS$_2$-BGaSe$_2$) MS vdWHs. These calculations give a new strategy for experimentalist to design advanced high-speed nanoelectronic devices based on VS$_2$-BGaX$_2$ (X=S, Se) MS vdWHs.