Gap States Assisted MoO3 Nanobelt Photodetector with Wide Spectrum Response

Abstract

Molybdenum oxides have been widely investigated for their broad applications ranging from electronics to energy storage. Photodetectors based on molybdenum trioxide (MoO 3), however, were seldom reported owing to their low conductivity and weak photoresponse. Herein we report a photodetector based on single MoO 3 nanobelt with wide visible spectrum response by introducing substantial gap states via H 2 annealing. The pristine MoO 3 nanobelt possessed low electrical conductance and no photoresponse for nearly all visible lights. The H 2 annealing can significantly improve the conductance of MoO 3 nanobelt and result in a good photodetector with wide visible spectrum response. Under illumination of 680 nm light, the photodetector exhibited high responsivity of ~56 A/W and external quantum efficiency of ~10200%. As corroborated by in situ ultraviolet photoelectron spectroscopy and X-ray photoelectron spectroscopy investigations, such strong wide spectrum photoresponse arises from the largely enriched gap states in the MoO 3 nanobelt after H 2 annealing.