Position-Controlled Hydrothermal Growth of Periodic Individual ZnO Nanorod Arrays on Indium Tin Oxide Substrate

Abstract

Periodic individual ZnO nanorod arrays were grown on indium tin oxide (ITO) conductive substrates buffered with a ZnO seed layer. Electron beam lithography was used to pattern the pre-coated poly(methyl methacrylate) (PMMA) layer into a periodic aperture template. Because of the constraint effects of this template, the ZnO nanorod arrays were strictly vertical to the substrate with a controlled pitch. To avoid damage to the electrical properties of conductive substrate, a low temperature (90 °C) hydrothermal route was adopted for the ZnO nanorod synthesis. The nutrient concentration played an important role in obtaining individual ZnO nanorod arrays. Several thin ZnO nanorods could merge into an individual ZnO nanorod at each aperture due to the increased lateral growth rate in ultra-high concentration (0.15 M) nutrient solution. Under the coaction of PMMA aperture template and hydrothermal growth, periodic individual ZnO nanorod arrays on nonsingle crystalline ITO substrates were successfully fabricated. The electrical properties of these periodic ZnO nanorods also were investigated, the current–voltage curve indicated that a barrier-free Ohmic contact formed between ZnO nanorod and ITO interface. The adjustable pitch and high conductance features of the periodic ZnO nanorod arrays made them high performance photoelectric devices.