Mar 15, 2012
Nanotree structures shaped with arborist-like precision
Morphological control over nanostructures during bottom-up growth is widely sought after. Glancing angle deposition (GLAD) is an advanced bottom-up nanostructuring technique developed by Michael Brett’s group at the University of Alberta, Canada. GLAD provides precision engineering of nanostructures via control over macroscopic geometry during deposition. Recently, GLAD was combined with vapour liquid solid (VLS) growth of indium tin oxide (ITO) nanowhiskers. This new technique, named VLS-GLAD, allows advanced control over ITO nanowhisker morphology and enables the team to tailor bulk optical and electrical properties of ITO nanowhisker films.
The ITO nanowhisker structure resembles a tree, with branches growing orthogonal to the primary growth direction, referred to as the trunk. VLS-GLAD provides scientists with an arborist’s ability to shape the branch architecture. The technique enables control over number density, diameter and branching of ITO nanowhiskers.
Deposition modulation allows for real-time fabrication of previously unachievable hybrid architectures during bottom-up growth. For example, with modulation of deposition rate and substrate orientation during growth, branches can be placed on selected regions of the trunk, and the trunk diameter can be controlled.
The work demonstrates the utility of VLS-GLAD in improving the control over the morphology of nanowhiskers, and the ability to fabricate hybridized nanostructures from the bottom-up. The group is currently working on implementing these structures in devices and expanding the technique to other materials.
Applications for ITO nanowhiskers include high surface area electrodes, gas sensors, protein molecule sensors and UV light sources.
The researchers presented their work in the journal Nanotechnology.
About the author
The study was conducted by Dr Michael Brett’s research group at the University of Alberta and the National Institute for Nanotechnology (NINT) in Edmonton, Canada. The Natural Sciences and Engineering Research Council of Canada, Alberta Innovates: Technology Futures, and Micralyne Inc. supported this work. Michael Brett is Professor of Electrical and Computer Engineering at the University of Alberta, and program co-ordinator for Energy Generation and Storage at NINT. Michael Taschuk is a research associate with Prof. Brett, studying nanostructured thin film fundamentals and applications. Allan Beaudry, Ryan Tucker and Joshua LaForge are graduate students working under the supervision of Dr Brett. Imaging was conducted on the NINT Microscopy group’s equipment and Kai Cui performed the TEM work.