Spatiotemporal Imaging of Thickness-Induced Band-Bending Junctions

Van der Waals materials exhibit naturally passivated surfaces and can form versatile heterostructures, enabling observation of carrier transport mechanisms not seen in three-dimensional materials. Here we report a "band bending junction", new type semiconductor homojunction whose surface potential landscape depends solely on difference thickness between the two regions atop buried heterojunction interface. Using MoS2 Au to interface, find that lateral differences arise from local extent vertical band thin thick regions. scanning ultrafast electron microscopy, examine spatiotemporal dynamics photogenerated charge carriers separation is enabled by junction, which confirmed with simulations. Band junctions may therefore enable electronic optoelectronic devices rely variations rather than doping separate carriers.