  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 and van der Waals (vdW) heterointerface of those
have emerged as suitable candidates for such ultra-low power nanoelectric
devices. In this work, employing density functional theory (DFT), the monolayer
ReS2 / monolayer MoTe2 vdW heterostructure with Sulphur vacancy is studied to
examine various ground state electronic properties. Changes in effective band
gap owing to defect-induced states and modulation of the energy gap value with
Molybdenum (Mo) and Oxygen (O) adsorption at the defect site are examined.
Since two-dimensional (2D) material based nanoscaled devices exhibit promising
switching between non-conducting and conducting states, determining the role of
defect-induced states and the adsorption of atoms/molecules on surfaces is
crucial. Here, 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 adsorption energy of adatoms binding at the defect
site.
