Electrical transport properties of single ZnO nanorods

Catalyst-driven molecular beam epitaxy was used to grow single ZnO nanorods with diameters of ∼130 nm on Au-coated Al ₂O ₃ substrates. As a function of both temperature and gas ambient, the current-voltage characteristics of single ZnO nanorods were measured. 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, in the temperature range from 25 to 150 °C. 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, by sharp contrast.