Phototransistor Properties of Indium Tin Oxide Nanowires Grown by RF Sputtering Mechanism and Annealing Process

Abstract

Photoconducting properties of indium tin oxide (ITO) nanowires grown by RF sputtering associated with annealing process were studied. ITO nanowires have been grown without the use of catalysts or oblique deposition. The cubic cross-sectional nanowires length was of the order of several microns, while their diameter was ~150–250 nm. The photoluminescence (PL) analysis on nanowires proved their excellent photoemission characteristics. Devices based on ITO nanowires showed a substantial increase in conductance of up to three orders of magnitude upon exposure to UV light and showing reproducible UV photoresponse and remaining relatively stable. The rising speed is slightly reduced, while the decay time is prolonged. Such devices also exhibited short response times and significant shifts in the threshold gate voltage. It was found that the dynamic response of the ITO nanowires phototransistor was stable with an on/off current contrast ratio of around 101. It is thus found that the change in the carrier concentrations in constant gate voltage was enhanced by 1.12 × 1017 cm-3 for the 350 nm UV light, corresponding to threshold-voltage shifts of before to after UV-light exposition. The photoconductive gain corresponding to responsivity measured at 350 nm was 0.11 × 105.