Highly Uniform Epitaxial ZnO Nanorod Arrays for Nanopiezotronics

Abstract

Highly uniform and c-axis-aligned ZnO nanorod arrays were fabricated in predefined patterns by a low temperature homoepitaxial aqueous chemical method. The nucleation seed patterns were realized in polymer and in metal thin films, resulting in, all-ZnO and bottom-contacted structures, respectively. Both of them show excellent geometrical uniformity: the cross-sectional uniformity according to the scanning electron micrographs across the array is lower than 2%. The diameter of the hexagonal prism-shaped nanorods can be set in the range of 90–170 nm while their typical length achievable is 0.5–2.3 μm. The effect of the surface polarity was also examined, however, no significant difference was found between the arrays grown on Zn-terminated and on O-terminated face of the ZnO single crystal. The transmission electron microscopy observation revealed the single crystalline nature of the nanorods. The current–voltage characteristics taken on an individual nanorod contacted by a Au-coated atomic force microscope tip reflected Schottky-type behavior. The geometrical uniformity, the designable pattern, and the electrical properties make the presented nanorod arrays ideal candidates to be used in ZnO-based DC nanogenerator and in next-generation integrated piezoelectric nano-electromechanical systems (NEMS).

One-dimensional ZnO nanostructures: Solution growth and functional properties

“…30(c)-30(f) [48]. Single crystal ZnO wafers with or without metallic Ru thin film coating have also been used to grow well-aligned ZnO nanowire arrays [277]. The as-grown nanowires exhibited a remarkable vertical alignment and uniformity in diameter and length.…”

Improving the performance of inorganic-organic hybrid photovoltaic devices by uniform ordering of ZnO nanorods and near-atmospheric pressure nitrogen plasma treatment

“…The surface was then dry etched with oxygen plasma gas to remove all residual PMMA resist. The ZnO NRs were grown in a sealed glass container filled with an aqueous solution of zinc nitrate hexahydrate (Zn(NO 3 ) 2 Á6H 2 O) and hexamethylenetetramine (C 6 H 12 N 4 ) with an equimolar concentration of 0.012M at 85 C for 6 h. 27,28 Finally, the PMMA resist was removed in acetone and ethanol, and the NRs were immediately rinsed with deionized water.…”

Morphology and crystallinity control of wet chemically grown ZnO nanorods

“…The process flow for the fabrication of the ZnO NRs is shown in Figure 1 and reported in [22]. Each seed surface was first washed ultrasonically in acetone, ethanol, and deionized water (Figure 1a).…”