摘要： The transition metal dichalcogenides (TMDCs) have been intensively investigated as one of promising nanoelectronic and optoelectronic materials. However, the pervasive adsorbates on the surface of monolayer TMDCs, including oxygen and water molecules from the ambient environments, predominately degrade the device performance, thus hindering the precise applications. In this work, we report the effect of laser irradiation on the transport and photoresponse of monolayer MoS2 and WSe2 devices, and this laser annealing process is demonstrated as one straightforward approach to remove the physically adsorbed contaminations. Compared with vacuum pumping and in-situ thermal annealing treatments, the field-effect transistors after the laser annealing show more than one order of magnitude higher on-state current, and no apparent degradation of device performance at low temperature. The mobility of monolayer WSe2 devices can be enhanced by 3-4 times, and for single-layered MoS2 devices with the commonly used SiO2 as the back-gate, the mobility increases by 20 times, reaching 37 cm2 ? V?1 ? s?1. The efficient cleaning effect of the laser annealing is also supported by the reduction of channel and contact resistances revealed by the transmission line experiment. Further, the enhanced photocurrent by a factor of 10 has been obtained in the laser annealed device. These findings pave the way for the high-performance monolayer TMDCs-based electronic and optoelectronic devices with the clean surface and intrinsic properties.