Abstract
Crystal growth often proceeds by atomic step flow. When the surface area available for growth is limited, the nucleation and progression of the steps can be affected. This issue is particularly relevant to the formation of nanocrystals. We examine the case of Au-catalyzed GaAs nanowires, which we grow in a transmission electron microscope. Our in situ observations show that atomic layers nucleate at the periphery of the interface between the nanowire and the catalyst droplet. From this starting location, the atomic step flows within a restricted area of hexagonal shape. At specific partial coverages, the monolayer configuration changes abruptly. A simple model based on the geometry of the system and its edge energies explains these observations. In particular, we observe an inversion of the step curvature which reveals that the effective energy per unit length of monolayer edge is much lower at the interface periphery than inside the catalyst droplet.
- Received 26 April 2018
- Revised 14 July 2018
DOI:https://doi.org/10.1103/PhysRevLett.121.166101
© 2018 American Physical Society
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Video—Growing a Crystal One Atomic Layer at a Time
Published 19 October 2018
An electron microscope captures new atomic layers forming and spreading across the surface of a growing nanocrystal.
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