Electrodeposition efficiency of Ni in the fabrication of highly orderednanowire arrays: The roles of Cu pre-plating and barrier layertemperature

Abstract

tInvestigation of new parameters affecting the electrodeposition process of nanowires (NWs) grown insolid templates is of considerable significance. In this work, the electrodeposition efficiency (EE) of Niin the fabrication of arrays of pulsed ac electrodeposited NWs embedded in porous aluminum oxidetemplate was investigated. By filling the branched nanopores formed at the bottom of aligned poreswith Cu prior to the electrodeposition of Ni and also optimizing the alumina barrier layer temperature(TBL), a steady-state electrodeposition was created at a high current density (jed) of 60 mA/cm2. This wasaccompanied by a significant improvement in the EE of Ni and uniformity of 35 nm diameter NWs. In thisrespect, while a non-uniform growth of Ni NWs with an average length of 1.5 m was obtained due toan EE of 10% using TBL∼ 8◦C, the use of TBL∼ 24◦C led to a uniform growth of 9 m long NWs as a resultof an EE of 55%. Alternatively, the crystallinity of Ni NWs along the [2 2 0] direction and their magneticproperties were considerably improved by increasing jedfrom 15 to 60 mA/cm2, so that an approximately95% increase in axial coercivity (from 570 to 1100 Oe) was achieved.