Adsorption of Mo and O at S-vacancy on ReS2 surface of ReS2/MoTe2 vdW heterointerface

Applications like high density information storage, neuromorphic computing, nanophotonics, etc. require ultra-thin electronic devices which can be controlled with applied electric field. Of late, atomically thin two-dimensional (2D) materials based van der Waals (vdW) heterointerfaces have emerged as suitable candidates for ultra-low power nanoelectric devices. In this work, employing density functional theory (DFT), the monolayer ReS₂/monolayer MoTe₂ vdW heterostructure with Sulfur vacancy is studied to examine various ground state electronic properties. Here, we emphasize the changes in effective band gap owing to defect-induced states as well as modulation of the energy gap value with Molybdenum (Mo) and Oxygen (O) adsorption at the defect site. Nanoscaled devices based on atom-thin 2D layered materials, exhibit promising switching between non-conducting and conducting states. Therefore, determining the role of defect-induced states and the adsorption of atoms/molecules on surfaces is crucial. Moreover, a detailed theoretical study to determine surface properties and relative energetic stability of the vdW heterostructures is carried out. The charge re-distribution between the constituent layers is also analyzed by obtaining Electron Difference Density (EDD) for different heterointerfaces. Nonetheless, the efficacy of switching between non-conducting and conducting states is assessed based on the adsorption energy of adatoms binding at the defect site.