Anodised aluminum oxide (AAO) templates are used as hosts for growing metallic and semiconductor nanowires and nanocables. Although chemical vapour, electrochemical, electroless deposition and sol-gel methods were being commonly employed to generate a wide range of nanostructures inside pores, Ge nanowires inside an AAO matrix were successfully grown using only the supercritical fluid method. However, resitivities of these nanowires are 2-3 orders of magnitude higher in comparison to the bulk material [1].
In this study the conductive properties of Ge nanostructures grown by the new 'in-place' approach within the channels of the AAO are characterized. This approach combines the gold nanoparticle seeded growth of semiconductor nanowires with the highly anisotropic structure of aligned channel substrates. Whether nanowires have polycrystalline or monocrystalline structure depends on the growth conditions.
In order to determine the conductivity of individual nanowires inside the matrix, samples were thinned until their thickness was below 1 µm using standard techniques for sample preparation intended for imaging inside transmission electron microscopes (TEM). The presence of the nanowires inside pores and its crystallinity was controlled by TEM and SEM. Conductive AFM (Asylum research) in contact mode was used for the surface conductivity mapping.
It was found that the resistivity of nanowires grown from gold seeded nanostructures is lower in comparison to the nanowires that are synthesized earlier with the SCF method [1] and is close to the resistivity of bulk germanium.
1. D. Erts, B. Polyakov, B. Daly, M. A. Morris, S. Ellingboe, J. Boland, J. D. Holmes. J. Phys. Chem. B, 110, 820 (2006). |