Ab-initio study of doping versus adsorption in monolayer M0S2

To modulate the conductivity of channel as well as for controlling threshold voltage of the device doping is required. Sometimes this doping can be unintentional via adsorption of impurities. We have found by ab-initio density functional theory calculations that K and Nb atoms change the system into n-type, and Br changes into p-type if adsorbed on monolayer of MoS₂. Similarly Cl, V and P introduce mid-gap states/trap levels in the band gap for adsorption. In case of substitutional doping, it is found that P and Nb make monolayer MoS₂ p-type if these elements replace the S atom and the Mo atom, and Cl makes it degenerate n-type if it replaces the S atom in monolayer MoS₂.