Fabrication and atmospheric-pressure-dependent electrical properties of a ZnO nanowire device

A single ZnO nanowire device was fabricated by electron-beam lithography, and its current-voltage characteristics were recorded while varying the atmospheric pressure to test possible applications as a chemical gas sensor. Vertically well aligned ZnO nanowires were grown on GaN epilayer on c-plane sapphire via a vapor-liquid-solid (VLS) process by introducing an Au thin film (3 nm) as a catalyst. Semiconducting nanowire devices were fabricated by using photolithography and e-beam lithography, and their electrical properties were studied. To realize reliable device operation, which is a key factor for a chemical sensor, the contact resistance should be optimized. Here, we studied the contact-resistance problem by using a scanning probe microscopic tool to characterize surface-potential behaviors. To overcome the contact-resistance problem, a post thermal process was adapted to the nanowire device. Atmospheric-pressure-dependent electrical properties of the ZnO nanowire device were studied for chemical-sensor application.