High Responsivity and Photovoltaic Effect Based on Vertical Transport in Multilayer α‐In2Se3

Herein, device demonstration based on vertical transport in multilayer α‐In2Se3 is reported. Photodetectors realized using a metal/α‐In2Se3/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 >1013 cm Hz0.5 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‐In2Se3 junction resulted in a photovoltaic effect with VOC ≈0.1 V and ISC ≈0.4 μA under an illumination of 520 nm. A vertical metal–semiconductor–metal photodetector implemented using α‐In2Se3 flake is studied. The proposed photodetector attains a very high spectral responsivity and detectivity at a visible wavelength of 680 nm. An asymmetric barrier arising out of ITO and Au contacts results in photovoltaic effect. The results reveal the photodetector as a suitable candidate for ultrasensitive detection.