Ballistic transport and optical properties of a new half-metallic monolayer: Vanadium phosphide

Abstract

In this work, a new monolayer structure, vanadium phosphide (VP) was predicted by first principles approach. Dynamical and thermal stabilities of monolayer VP were confirmed by phonon dispersion and ab initio molecular dynamics calculations. Monolayer VP was found as half-metallic material with an electronic band gap of 1.73 eV in spin down channel, while up spins display metallic band structure yielding a spin-polarized conductivity. However, an applied electric field in perpendicular-to-plane direction gradually reduces the band gap value. The current-voltage analysis indicates negative differential resistance behavior at room temperature. Besides, high optical conductivity is remarkable for optoelectronic applications. The geometric and electronic structures of bilayer VP, MoS2/VP and bP/VP heterostructures were also revealed. The half-metallic nature of pristine VP is preserved in bilayer form with indirect-to-direct band gap transition in spin down channel, which is an important implication for band gap engineering and practical device applications. The novel VP monolayer system has rich functional properties as a promising 2D material.