van der Waals heterojunctions formed by stacking various two-dimensional (2D) materials have a series of attractive physical properties, thus offering an ideal platform for versatile electronic and optoelectronic applications. Here,… Click to show full abstract
van der Waals heterojunctions formed by stacking various two-dimensional (2D) materials have a series of attractive physical properties, thus offering an ideal platform for versatile electronic and optoelectronic applications. Here, we report few-layer SnSe/MoS2 van der Waals heterojunctions and study their electrical and optoelectronic characteristics. The new heterojunctions present excellent electrical transport characteristics with a distinct rectification effect and a high current on/off ratio (∼1 × 105). Such type-II heterostructures also generate a self-powered photocurrent with a fast response time (<10 ms) and exhibit high photoresponsivity of 100 A W-1, together with high external quantum efficiency of 23.3 × 103% under illumination by 532 nm light. Photoswitching characteristics of the heterojunctions can be modulated by bias voltage, light wavelength, and power density. The designed novel type-II van der Waals heterojunctions are formed from a combination of a transition-metal dichalcogenide and a group IV-VI layered 2D material, thereby expanding the library of ultrathin flexible 2D semiconducting devices.
               
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