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Crystal Structure Transfer in Core/Shell Nanowires

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journal contribution
posted on 13.04.2011, 00:00 by Rienk E. Algra, Moïra Hocevar, Marcel A. Verheijen, Ilaria Zardo, George G. W. Immink, Willem J. P. van Enckevort, Gerhard Abstreiter, Leo P. Kouwenhoven, Elias Vlieg, Erik P. A. M. Bakkers
Structure engineering is an emerging tool to control opto-electronic properties of semiconductors. Recently, control of crystal structure and the formation of a twinning superlattice have been shown for III−V nanowires. This level of control has not been obtained for Si nanowires, the most relevant material for the semiconductor industry. Here, we present an approach, in which a designed twinning superlattice with the zinc blende crystal structure or the wurtzite crystal structure is transferred from a gallium phosphide core wire to an epitaxially grown silicon shell. These materials have a difference in lattice constants of only 0.4%, which allows for structure transfer without introducing extra defects. The twinning superlattices, periodicity, and shell thickness can be tuned with great precision. Arrays of free-standing Si nanotubes are obtained by a selective wet-chemical etch of the core wire.