Stress-dopant interplay in halogen-modified WS2 monolayers: insights from first-principles

We present a detailed ab-initio study, based on density functional theory (DFT), to investigate the coupled effects of external mechanical stress and halogen doping on monolayer tungsten disulfide (WS2). Both compressive and tensile stress conditions were considered for undoped, Iodine-substituted, Iodine-adsorbed, and Fluorine-adsorbed WS2 systems. Our analysis reveals that the bandgap of WS2 is strongly modulated under strain, with tensile stress showing a more pronounced effect compared to compressive stress owing to changes in orbital interaction. We also obtained a bandgap change of -55.74 meV for 1% tensile strain as reported in the literature. The charge redistribution is found to be highly sensitive to stress, influencing the doping nature of halogen impurities. Specifically, iodine substitution consistently enhances n-type behavior, while iodine and fluorine adsorption promote p-type conductivity, with the degree of doping strongly dependent on the applied stress. These insights highlight the critical interplay between mechanical and chemical modifications, paving the way for strain- and dopant-engineered WS2 channels in next-generation nanoelectronic devices.