Tunable channel width of a UV-gate field effect transistor based on ZnO micro-nano wire

Abstract

A n-channel field effect transistor (FET) based on ZnO microwire has been fabricated for ultraviolet detection, where a PEDOT:PSS/ZnO wire junction serves as the gate. The sensitivity of the junction FET was enhanced by two orders of magnitude with a fast response time <1 s at 3 V compared with a Ag–ZnO–Ag detector under the illumination of UV light (325 nm). Such a great improvement in photoresponse is attributed to the introduction of a depletion layer, resulting in a lower dark current. The change of the junction FET channel width with various UV light intensities was calculated and discussed in terms of the carrier diffusion theory and the ideal I–V characteristics of the depletion mode JFET.