Ultrasensitive visible light photoresponse and electrical transportation properties of nonstoichiometric indium oxide nanowire arrays by electrospinning

Abstract

We report on the below-bandgap photoresponse and electrical properties of In₂O₃ nanowires fabricated by a low-cost electrospinning technique. The as-prepared In₂O₃ nanowires show ultra-high sensitivity up to 10³ to 10⁴ with a much broadened response spectrum which is extended to the visible region. The dramatically enhanced photoconduction under below-bandgap light illumination is attributed to the transition from defect levels, which are introduced by oxygen vacancies present in the nonstoichiometric In₂O_2.68 nanowires. The underlying mechanism is further clarified by the UV-vis absorption and photoluminescence spectra, where an obvious red shift in the absorption edge and a remarkable emission peak covering the visible region are detected. Moreover, electrical characterizations of bottom-up-assembled field effect transistors (FETs) confirm the intrinsic n-type semiconducting behavior with an increased electron concentration, strongly indicating the formation of donor levels which induce the below-bandgap photoresponse. The concept of realizing dual-band photodetection in a single semiconductor system holds great promise in the fields of energy conversion, fire/flame detection and other military applications.