Chemical vapor deposited WS2/MoS2 heterostructure photodetector with enhanced photoresponsivity

Two-dimensional transition metal dichalcogenides (TMDCs) have attracted great interest due to their unique semiconductor properties. Among all TMDC materials, MoS2 and WS2 are promising for composing heterostructures. However, traditional TMDC heterostructure fabrication depends on transfer process, with drawbacks of interface impurity and small size. In this work, a two-step chemical vapor deposition (CVD) process was applied to synthesize large-scale WS2/MoS2 heterostructure. Surface morphology and crystal structure characterizations demonstrate the high-quality WS2/MoS2 heterostructure. The WS2/MoS2 heterostructure photodetector fabricated by photolithography exhibits an enhanced photoresponsivity up to 370 A W-1 in comparison with single WS2 or MoS2 devices. This study suggests a direct CVD growth of large-scale TMDC heterostructure films with clean interface. The built-in electric field at interface contributes to the separation of photo-generated electron-hole pairs, leading to enhanced photocurrent and responsivity, and showing promising potentials in photo-electric applications.