Aligned Co nanodiscs by electrodeposition on GaAs

Aligned cobalt nanodiscs have been electrodepo sited on GaAs (110), (111), and (0031) substrates from weakly acidic, cobalt sulphate (CoSO4) and ammonium sulphate [(NH4)(2)SO4] Solutions. The thickness and diameter of the nanodiscs are about 50 and 500 nm, respectively. They have an HCP crystal structure with their [0001] c-axis perpendicular to the disc normal and aligned with the low mismatch in-plane GaAs < 110 > directions. They dominate the growth after an initial layer containing a mixture of BCC and HCP cobalt. Random alignment results for deposition from pure CoSO4 electrolyte [no (NH4)(2)SO4], or acidic [by adding H2SO4], or basic [by adding (NH4)OH] CoSO4 solutions. (c) 2005 Elsevier B.V. All rights reserved.