Electrical transport properties of single ZnO nanorods

Single ZnO nanorods with diameters of similar to130 nm were grown on Au-coated Al2O3 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 degreesC, the resistivity of nanorods treated in H-2 at 400 degreesC prior to measurement showed an activation energy of 0.089+/-0.02 eV and was insensitive to the ambient used (C2H4,N2O,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. (C) 2004 American Institute of Physics.