High Responsivity and Photovoltaic Effect Based on Vertical Transport in Multilayer α‐In ₂ Se ₃

Herein, device demonstration based on vertical transport in multilayer α‐In 2 Se 3 is reported. Photodetectors realized using a metal/α‐In 2 Se 3 /indium tin oxide (ITO) vertical junction exhibit clear signature of the band edge in spectral responsivity. The wavelength at 680 nm corresponding to an ultrahigh responsivity of 1000 A W −1 and a detectivity of >10 13 cm Hz 0.5 W −1 at a bias of 0.5 V. The variation of responsivity and detectivity with optical power density is studied, and a transient response of 20 ms is obtained for the devices (instrument limitation). In addition, an asymmetric barrier height arising out of ITO and Au contacts to a vertical α‐In 2 Se 3 junction resulted in a photovoltaic effect with V OC ≈0.1 V and I SC ≈0.4 μA under an illumination of 520 nm.