Theoretical Insights to Niobium-Doped Monolayer MoS2–Gold Contact

Abstract

We report a first principles study of the electronic properties for a contact formed between Nb-doped monolayer MoS2 and gold for different doping concentrations. We first focus on the shift of energy levels in band structure and the density of states with respect to the Fermi level for a geometrically optimized $5\times 5$ MoS2 supercell for both pristine and Nb-doped structures. The doping is achieved by substituting Mo atoms with Nb atoms at random positions. It is observed that for an experimentally reported sheet hole doping concentration of ( $\rho _{2D}$ ) $1.8\times 10^{14}$ cm $^{-2}$ , the pristine MoS2 converts to degenerate p-type semiconductor. Next, we interface this supercell with six layers of $\langle 111\rangle $ cleaved surface of gold to investigate the contact nature of MoS2–Au system. By careful examination of projected band structure, projected density of states, effective potential and charge density difference, we demonstrate that the Schottky barrier nature observed for pure MoS2–Au contact can be converted from n-type to p-type by efficient Nb doping.