Hybrid WSe-InO Phototransistor with Ultrahigh Detectivity by Efficient Suppression of Dark Currents.

Photodetectors based on low-dimensional materials have attracted tremendous attention because of their high sensitivity and compatibility with conventional semiconductor technology. However, up until now, developing low-dimensional phototransistors with high responsivity and low dark currents over broad-band spectra still remains a great challenge because of the trade-offs in the potential architectures. In this work, we report a hybrid phototransistor consisting of a single InO nanowire as the channel material and a multilayer WSe nanosheet as the decorating sensitizer for photodetection. Our devices show high responsivities of 7.5 × 10 and 3.5 × 10 A W and ultrahigh detectivities of 4.17 × 10 and 1.95 × 10 jones at the wavelengths of 637 and 940 nm, respectively. The superior detectivity of the hybrid architecture arises from the extremely low dark currents and the enhanced photogating effect in the depletion regime by the unique design of energy band alignment of the channel and sensitizer materials. Moreover, the visible to near-infrared absorption properties of the multilayer WSe nanosheet favor a broad-band spectral response for the devices. Our results pave the way for developing ultrahigh-sensitivity photodetectors based on low-dimensional hybrid architectures.