Electrical and gas sensing properties of ZnO nanorod arrays directly grown on a four-probe electrode system

A method for measuring the electrical characteristics of aligned ZnO nanorod arrays (NRAs) directly grown on a pre-patterned four-point probe system in solution was proposed. This four-probe method enabled us to perform electrical measurements directly on the as-grown ZnO nanorod arrays without any additional processing. The location, shape and length of the rods directly grown on the four-probe electrodes were well controlled. The current–voltage characteristics showed a low turn-on voltage and a high saturation current. These ZnO NRAs devices were implemented as gas sensors for detecting hydrogen. The sensitivity increased with the concentration of H2 and the operating temperature.