Ultra-high responsivity and photovoltaic effect based on vertical transport in multi-layer $\alpha$ -In2Se3

We report on the first demonstration of photodetector as well as the observation of photovoltaic effect based on vertical transport in multilayer α -In ₂ Se ₃ . A metal/α-In ₂ Se ₃ /ITO vertical junction was used to achieve an ultra-high responsivity of 1000 A/W even at a low bias of 0.5 V with a clear band-edge corresponding to multilayer α -In ₂ Se ₃ . Additionally, an asymmetric barrier height arising out of ITO and Au contacts to vertical α -In ₂ Se ₃ resulted in photovoltaic effect with V _OC ~ 0.1V and I _SC ~ 0.4μA under 520 nm illumination.