Self-powered, ultra-fast and high photoresponsivity of MoTe2/HfSe2 heterostructure broadband photovoltaic device

Due to their multifunctionality and tunable properties in electronic devices, the transition-metal dichalcogenides (TMDs) based van der Waals (vdW) heterostructures have attracted much attention and are considered a po-tential candidate for advanced nanoelectronics. In this work, a self-powered molybdenum ditelluride (MoTe2)/ hafnium diselenide (HfSe2) vdW heterostructure-based photodetector with ohmic contacts is designed. The high rectification ratio is attained as 1.9 x 106, rising from the clean interface and small barrier height. Photovoltaic experiments are also carried out using laser light with a wavelength of 532-1064 nm in visible and near-infrared (VNIR) regions with different power intensities ranging from 10 to 120 nW. The photoresponsivity of MoTe2/ HfSe2 is enhanced remarkably up to 1.3 x 103 A/W with detectivity 2.6 x 1013 Jones and external quantum efficiency of 68% because of band-to-band and interlayer TMDs charge transition at a longer wavelength (1064 nm). Under incoming light with an intensity of 120 nW, rapid growth (6.8 mu s) and decay times (8.7 mu s) are projected because of interlayer TMDs charge transition at the longer wavelength. The obtained results showed significantly higher values than the reported vdW heterostructures. The fast response time, low recombination rate and astonishing value of photoresponsivity are the key parameters to developing highly efficient TMDs-based solar devices.