Ultraviolet detection using TiO₂ nanowire array with Ag Schottky contact

Abstract

Abstract The glancing angle deposition technique has been employed to synthesize TiO 2 nanowire (NW) arrays which have been characterized by x-ray diffraction, field emission-scanning electron microscopy and high resolution transmission electron microscopy. Optical absorption measurements show the absorption edge at 3.42 eV and 3.48 eV for TiO 2 thin film (TF) and NW, respectively. The blue shift in absorption band is attributed to quantum confinement in NW structures. Photoluminescence measurement revealed oxygen-defect-related emission at 425 nm (∼2.9 eV). Ag/TiO 2 (NW) and Ag/TiO 2 (TF) contacts exhibit Schottky behaviour, and a higher turn-on voltage (∼6.5 V) was observed for NW devices than that of TF devices (∼5.25 V) under dark condition. In addition, TiO 2 -NW-based devices show twofold improvement in photodetection efficiency in the UV region, compared with TiO 2 -TF-based devices.