First-principles study of metal-semiconductor contact between MX2 (M = Nb, Pt; X = S, Se) monolayers

Abstract

First principles calculations are performed to investigate the structural and electronic properties of MX2 (M = Nb, Pt; X = S, Se) monolayers and their van der Waals (vdW) heterostructures. The dynamical stability of monolayers and vdW heterostructures is confirmed by binding energy and phonon spectra. An indirect band gap nature is found for PtS2 and PtSe2 monolayers while NbS2, NbSe2 and all vdW heterostructures are metals. The intrinsic electronic properties of both NbX2 and PtX2 are well preserved due to weak vdW contact. It is demonstrated that a p-type Schottky contact with a small barrier height is formed at NbX2-PtX2 interface. The zero tunnel barrier and higher potential drop across the interface in these contacts imply large transfer of charge carriers across the interface, making them potential candidates in nanoelectronic device applications.