High-performance WSe2 photodetector based on laser-induced p-n junction

摘要： Two-dimensional (2D) heterojunctions exhibit many unique features in nanoelectronic and optoelectronic devices. However, heterojunction engineering requires complicated alignment process and some defects are inevitably introduced during material preparation. In this work, a laser scanning technique is used to construct a lateral WSe2 p-n junction. The laser-scanned region shows a p-type behavior and the adjacent region is electrically n-doped with a proper gate voltage. The laser-oxidized product WOx is found to be responsible for this p-type doping. After laser scanning, WSe2 displays a change from ambipolar to unipolar p-type property. A significant photocurrent emerges at the p-n junction. Therefore, a self-powered WSe2 photodetector can be fabricated based on this junction, which presents a large photoswitching ratio of 106, high photoresponsivity of 800 mA W-1 and short photoresponse time with long-term stability and reproducibility. Therefore, this selective laser-doping method is prospective in future electronics applications.