Influence of Deposition Potential on Structure of ZnO Nanowires Synthesized in Track-Etched Membranes

Abstract

Single-crystal ZnO nanowires long up to several microns were fabricated by one-step electrochemical deposition. A template-based process employing track-etched polycarbonate (TE-PC) membranes was used for this purpose. The morphology and the structure characteristics of the ZnO nanowires were analyzed by means of Scanning Electron Microscopy (SEM), Focused Ion Beam (FIB), Transmission Electron Microscopy (TEM), and Selected Area Electron Diffraction (SAED). The growth process conditions turned out to have a marked influence on the crystal nature and morphology of the nanowires. Deposition rates ranging from 0.4 nm s −1 and up to 0.6 nm s −1 were recorded for the growth of ZnO nanowires. The obtained results showed that by using carefully controlled deposition conditions single crystalline nanowires and fine-grained structures can be routinely obtained. ZnO has extrusive physical properties such as a direct bandgap in the ultraviolet range (3.37 eV) or a large exciton binding energy (60 meV) which have made it a great application prospect.1, 2 ZnO nano-objects have been widely investigated in the recent years owing to promising applications in nanodevices. They showed high sensitivity to different chemicals, have piezo-and pyro-electric properties, etc. 3,4 As it has been shown that band edge, exciton energies, and UV luminescence of ZnO nanostructures are affected by crystallite size and crystal morphology, 5,6 it is desirable to tailor their electronic properties in order to exploit the broad range of applications.Nowadays, many efforts still focus on synthesizing oriented onedimensional ZnO nanostructures. Up to now, techniques using sophisticated and expensive equipments but also low temperature and cost-effective methods such as electrodeposition (ED) and hydrothermal deposition were employed for the synthesis of nanostructures. 7-9The major advantage of the electrochemical synthesis is given by its application for large area and high throughput productions, therefore suitable for an industrial use. [10][11][12][13] The ED of ZnO nanowires has been focused mostly on the preparation of nanorod/nanowire arrays by the template method and on flat substrates. 14, 15The ZnO electrodeposition is based on the reduction of an oxygen precursor such as dissolved molecular oxygen, nitrate ions or hydrogen peroxide. For example, Cembrero et al. 16 reported on the cathodic electrodeposition of ZnO nanocolumns and nanowires from zinc chloride solutions saturated in molecular oxygen. The general scheme for ED of ZnO employing different oxygen precursors is supposed as follows.The reaction at the cathode surface employing different oxygen precursors: The process evolves itself drifting the pH of the electrolyte to a constant increase and to a local supersaturation of the bath in the vicinity of the electrode, thus provoking the precipitation on the electrode surface of ZnO;18 therefore, if a specific crystal order is desired, the pH of the electrolytic solution has to be precisely controlled and adjusted to a proper value.As...

Nucleant layer effect on nanocolumnar ZnO films grown by electrodeposition

“…ZnO thin films have been prepared by a wide variety of techniques such as pulsed laser deposition [1,2], sputtering [3,4], and electrodeposition with or without templates [5-8]. In particular, the electrodeposition technique has advantages over other processes due to its simplicity, low equipment cost, and the possibility of obtaining large-area thin films.…”

Synthesis of ZnO Nanocrystals in SiO2/Si Track Template: Effect of Electrodeposition Parameters on Structure

“…In order to form ZnO phase by ECD, an electrolyte with the addition of oxygen precursors such as hydrogen peroxide (H 2 O 2 ), [18] nitrate anion NO 3 2À (Zn(NO 3 ) 2 ) [23] or molecular oxygen (O 2 ) [24] is used. Though, it is known that metal Zn is readily oxidizing in air ambient, and the ZnO formation can be achieved without oxygen precursor's addition into electrolyte.…”

“…[16,17] The ECD of ZnO nanowires in polymer etched ion-track templates has been reported by several authors employing various electrolytes. [18][19][20][21] Though, there are only a few studies devoted to the precipitation of ZnO nanocrystals in SiO 2 /Si track templates. In our previous article the Zn-based nanoparticles have been precipitated into nanoporous a-SiO 2 /Si-p templates using chemical and electrochemical deposition.…”

Effect of AZO film as seeding substrate on the electrodeposition and properties of Al-doped ZnO nanorod arrays

“…The nucleation and growth mechanism of ZnO in aqueous solutions have been previously investigated by numerous groups [12,13,31]. Here, we focus on zinc nitrate approach as the precursor of both the hydroxide ions and the zinc ions.…”

“…The electrochemical deposition technique has become an increasingly active research area in recent years due to its low cost, mild conditions and accurate process control [1]. It is well known that electrodeposition can be applied as nanostructuring technology to a wide range of materials including semiconductor oxides (such as ZnO nanowires) [12,13], graphene materials [14,15], metals (such as Cu nanowires) [16] and conducting polymers (such as poly(o-phenylene diamine)) [17].…”