  Investigation of a TMD-metal interface is essential for the effective
functioning of monolayer TMD based field effect transistors (FETs). In this
work, we employ Density Functional Theory (DFT) calculations to analyze the
modulation of the electronic structure of monolayer WS2 with chlorine doping
and the relative changes in the contact properties when interfaced with gold
and palladium. We initially examine the atomic and electronic structures of
pure and doped monolayer WS2 supercell and explore the formation of mid gap
states with band splitting near the conduction band edge. Further we analyze
the contact nature of the pure supercell with Au and Pd. We find that while Au
is physiosorped and forms n-type contact, Pd is chemisorped and forms p-type
contact with a higher valence electron density. Next, we study the interface
formed between the Cl-doped supercell and metals and observe a reduction in the
Schottky barrier height (SBH) in comparison to the pure supercell. This
reduction found is higher for Pd in comparison to Au which is further validated
by examining the charge transfer occurring at the interface. Our study confirms
that Cl doping is an efficient mechanism to reduce the n-SBH for both Au and Pd
which form different types of contact with WS2.

Mesoscale and Nanoscale Physics