A study on the electronic and interfacial structures of monolayer ReS₂-metal contacts

In this paper, we perform a systematic and rigorous study to evaluate the Ohmic nature of the top-contact formed by the monolayer ReS₂ (mReS₂) and metals (gold, silver, platinum, nickel, titanium, and scandium) by means of first-principles density functional theory calculations. We investigate the potential barrier, charge transfer and atomic orbital overlap at the mReS₂-metal interface in consideration of van der Waals forces to understand how efficiently carriers could be injected from the metal contact to the mReS₂ channel. ReS₂ is physisorbed on Au and Ag, which leads to little perturbation of its electronic structures and forms a larger Schottky contact and a higher tunnel barrier at the interface. ReS₂ is chemisorbed on Ti and Sc, where the bonding strongly perturbs the electronic structures and is found to be purely Ohmic. The bonding of ReS₂ on Pt and Ni lies between these two extreme cases, demonstrating an intermediate behavior. These findings not only provide an insight into the mReS₂-metal interfaces but may also prove to be instrumental in the future design of ReS₂-based devices with good performance.