High Responsivity and Photovoltaic Effect Based on Vertical Transport in Multilayer alpha-In2Se3

Herein, device demonstration based on vertical transport in multilayer alpha-In2Se3 is reported. Photodetectors realized using a metal/alpha-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 >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 alpha-In2Se3 junction resulted in a photovoltaic effect with V-OC approximate to 0.1 V and I-SC approximate to 0.4 mu A under an illumination of 520 nm.