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Atomic Scale Surface Structure and Morphology of InAs Nanowire Crystal Superlattices: The Effect of Epitaxial Overgrowth
journal contribution
posted on 2015-12-17, 07:38 authored by J. V. Knutsson, S. Lehmann, M. Hjort, P. Reinke, E. Lundgren, K. A. Dick, R. Timm, A. MikkelsenWhile shell growth engineering to
the atomic scale is important
for tailoring semiconductor nanowires with superior properties, a
precise knowledge of the surface structure and morphology at different
stages of this type of overgrowth has been lacking. We present a systematic
scanning tunneling microscopy (STM) study of homoepitaxial shell growth
of twinned superlattices in zinc blende InAs nanowires that transforms
{111}A/B-type facets to the nonpolar {110}-type. STM imaging along
the nanowires provides information on different stages of the shell
growth revealing distinct differences in growth dynamics of the crystal
facets and surface structures not found in the bulk. While growth
of a new surface layer is initiated simultaneously (at the twin plane
interface) on the {111}A and {111}B nanofacets, the step flow growth
proceeds much faster on {111}A compared to {111}B leading to significant
differences in roughness. Further, we observe that the atomic scale
structures on the {111}B facet is different from its bulk counterpart
and that shell growth on this facet occurs via steps perpendicular
to the ⟨112⟩B-type directions.