ZnO nanowire field-effect transistor as a UV photodetector; optimization for maximum sensitivity

We demonstrate that drain-source (V _ds) and gate-source voltages (V _gs) of a zinc oxide nanowire (ZnO NW) field-effect transistor (FET) can be optimized to increase UV photodetection sensitivity. Investigation of the relationship between the sensitivity and the applied voltages reveals that the photodetector is most sensitive when it operates (1) with highest on/off current ratio and (2) at the "bottom" of the subthreshold swing region. Our results can be broadly applied to maximize sensitivity of other FET-based sensors and detectors. A ZnO NW photodetector is most sensitive when V _gs is positioned at the "bottom" of the subthreshold swing region.