Influence of Dopant-Defect Coupling on Electronic Properties of Vanadium-Doped Tungsten Disulfide Monolayers

Substitutional doping of metal sites is a promising approach to tune the optical, electronic, and magnetic properties of transition metal dichalcogenides (TMDs). However, confinement in the two-dimensional basal planes of TMDs can cause strong interactions and coupling of substitutional dopant atoms with intrinsic defects, which can modify their doping and defect chemistries. We explore these interactions using temperature-dependent photoluminescence (PL) spectroscopy and atomic scale scanning transmission electron microscopy of p-type vanadium dopant atoms with sulfur vacancy defects in WS₂ monolayers synthesized via atmospheric pressure chemical vapor deposition. Doping WS₂ with less than 0.2 atom% vanadium reduces the density of electrons emitted into conduction band states from sulfur vacancy defects, reduces the optical signatures of negative trions, and enhances the PL quantum yield of the material. At significantly greater concentrations, vanadium dopants interact with and modify the electronic states associated with intrinsic defects, leading to quenched PL and mid-gap states with energies that depend sensitively on vanadium concentration. Our findings layout a framework for controlled synthesis and doping of p-type TMDs with tunable optical and electronic properties for applications in catalysis, dilute magnetic semiconductors, and quantum photonic devices among others.