Electrodeposition efficiency of Ni in the fabrication of highly ordered nanowire arrays: The roles of Cu pre-plating and barrier layer temperature

Abstract Investigation of new parameters affecting the electrodeposition process of nanowires (NWs) grown in solid templates is of considerable significance. In this work, the electrodeposition efficiency (EE) of Ni in the fabrication of arrays of pulsed ac electrodeposited NWs embedded in porous aluminum oxide template was investigated. By filling the branched nanopores formed at the bottom of aligned pores with 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 was accompanied by a significant improvement in the EE of Ni and uniformity of 35 nm diameter NWs. In this respect, while a non-uniform growth of Ni NWs with an average length of 1.5 μm was obtained due to an EE of 10% using TBL ∼ 8 °C, the use of TBL ∼ 24 °C led to a uniform growth of 9 μm long NWs as a result of an EE of 55%. Alternatively, the crystallinity of Ni NWs along the [2 2 0] direction and their magnetic properties were considerably improved by increasing jed from 15 to 60 mA/cm2, so that an approximately 95% increase in axial coercivity (from 570 to 1100 Oe) was achieved.