Ex-situ plasma doping of MoS2 thin films synthesised by thermally assisted conversion process: Simulations and experiment

Controllable doping of two-dimensional (2D) materials is one of the main research challenges associated with the practical realization of 2D semiconductors in hetero-and homo-junctions. We report that the selected-area treatment of MoS2 films with nitrogen plasma can modify the resistivity of the film. To identify the underlying physical mechanism responsible for such observation, we systematically investigated the transport properties of cTLM-patterned contacts on ~70nm non-intentionally doped (NID), p-and p-doped MoS 2 films before and after plasma exposure. Electrical characterization demonstrates that p-type doping of MoS2 is achieved by plasma-induced nitrogen doping. HR-TEM images confirm that no etching of the exposed film has occurred. Our experimental observations are supported by first principles atomic scale simulations suggesting the interaction of nitrogen with defects and vacancies in the poly-crystalline MoS2 films as the origin of doping mechanism. The results indicate low-power nitrogen plasma is an effective approach for ex-situ doping of MoS2