Fabrication of ZnO nanorods on O-polar ZnO layers grown by molecular beam epitaxy and electrical characterization using conductive atomic force microscopy

Using the aqueous solution with microwave-assisted heating, ZnO nanorods were fabricated on an O-polar single crystal molecular beam epitaxial grown ZnO layer. Film-like ZnO due to aggregation of nanorods was observed when heated at 95 degrees C with a precursor concentration of 100 mM. On the other hand, hexagonal ZnO nanorods with well-defined orientation were achieved by lowering the reaction temperature down to 60 degrees C with a precursor concentration of 10 mM. The top surface of the hexagonal ZnO nanorods has a roughness of a few nm, revealed by means of atomic force microscopy (AFM). Conductive-AFM measurement indicates Schottky rectifying behavior in Au-coated cantilever/ZnO nanorods. The current-voltage characteristics are discussed in connection with the loading force of AFM measurements.