Recently,two-dimensional materials have been attracting increasing attention because of their novel properties and promising applications.However,the impurity doping remains a significant challenge owing to the lack of the doping strategy in the atomically thin layers.Here we report on the chromium (Cr) and manganese (Mn) doping in atomically-thin MoS2 crystals grown by chemical vapor deposition.The Cr/Mn doped MoS2 samples are characterized by a peak at 1.76 and 1.79 eV in photoluminescence spectra,respectively,compared with the undoped one at 1.85 eV.The field-effect transistor (FET) devices based on the Mn doping show a higher threshold voltage than that of the pure MoS2 while the Cr doping exhibits the opposite behavior.Importantly,the carrier concentration in these samples displays a remarkable difference arising from the doping effect,consistent with the evolution of the FET performance.The temperature-dependent conductivity measurements further demonstrate a large variation in activation energy.The successful incorporation of the Mn and Cr impurities into the monolayer MoS2 paves the way towards the high Curie temperature two-dimensional dilute magnetic semiconductors.