Expeditious UV detection of tungstite (WO3·H2O) and tungsten oxide (WO3) decorated multiwall carbon nanotubes (MWCNT) based photodetector: ultrafast response and recovery time

Abstract

Tungstite (WO 3 ·H 2 O) and tungsten oxide (WO 3 ) decorated multi-walled carbon nanotube (MWCNT) based ultra-fast UV photodetectors were fabricated and characterized in this work. Tungstite was synthesized by wet chemical route and tungsten oxide was derived by calcinating tungstite at elevated temperatures (723 K and 1023 K). The crystal structures of tungstite and tungsten oxide were confirmed from X-ray diffraction analysis. The UV photo responsive behavior of the tungstite and tungsten oxide decorated MWCNT UV photodetectors were studied using 365 nm UV LED array in the intensity range 15-83 μW cm −2 . The device showed good UV photoresponsivity with high external quantum efficiency (EQE). Tungstite decorated MWCNT UV photodetector exhibited maximum responsivity of 7.4 AW −1 along with EQE of 2550% under the incident UV intensity of 15 μW cm −2 . Up to 500 Hz optical chopping frequency, the devices showed remarkable stability along with good repeatability of UV detection. Response and recovery time is recorded as low as 400 μs and 500 μs respectively for tungstite decorated UV photodetectors.