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S.T. Boles, O.M. Nayfeh, C.K.F. Ho, D.A. Antoniadis, E.A. Fitzgerald, C.V. Thompson
Sponsorship: Singapore-MIT Alliance The vapor-liquid-solid mechanism for growth of single crystal whis-
kers and wires was originally discovered in the 1960s but has only
recently been rediscovered as a way to fabricate high-performance
nanoscale electronic devices, with dimensions below those attain-
able with photolithography. Although a great deal of attention has
been focused on the electronic properties of Si and III-V nanowires,
many of the physical mechanisms involved in growing these single
crystal wires remain unclear. We have been investigating the im-
portance of catalyst size and shape for wire growth morphology by
using evaporated island catalysts, catalysts derived from dewetted
thin films, and commercially available nanoparticles. Optimizing
catalyst processing conditions and combining them with specific to-
pographies or templates, such as inverted pyramid arrays or silicon
| | dioxide gratings, achieves precise control over catalyst placement
and subsequent nanowire placement. Also in this study, the role of
growth conditions has been investigated by controlling the growth
temperature, the partial pressures of reactants and the conditions
of pre-growth annealing. These parameters have been determined
to be critical not only to stable and repeatable growth of Si and III-V
nanowires, but also to controlling the relative orientation and defect
generation at the substrate-wire interface.
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Figure 1: Si nanowires grown on Si <111> substrates using Au
catalysts.
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Figure 2: GaP nanowire grown on Si <111> substrate using Ag
catalyst.
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Research Topics 
Catalyst Engineering and Growth Mechanisms of Si and III-V Nanowires