Electrical transport properties of single ZnO nanorods

Single ZnO nanorods with diameters of ∼ 130 nm were grown on Au-coated Al 2 O 3 substrates by catalyst-driven molecular beam epitaxy. Individual nanorods were removed from the substrate and placed between Ohmic contact pads and the current-voltage characteristics measured as a function of temperature and gas ambient. In the temperature range from 25 to 150 ° C , the resistivity of nanorods treated in H 2 at 400 ° C prior to measurement showed an activation energy of 0.089 ± 0.02 eV and was insensitive to the ambient used ( C 2 H 4 , N 2 O , O 2 or 10% H 2 in N 2 ). By sharp contrast, the conductivity of nanorods not treated in H 2 was sensitive to trace concentrations of gases in the measurement ambient even at room temperature, demonstrating their potential as gas sensors.