In situ investigation of explosive crystallization in a-Ge: Experimental determination of the interface response function using dynamic transmission electron microscopy
Nikolova, Liliya, Stern, Mark J., MacLeod, Jennifer M., Reed, Bryan W., Ibrahim, Heide, Campbell, Geoffrey H., Rosei, Federico, LaGrange, Thomas, & Siwick, Bradley J. (2014) In situ investigation of explosive crystallization in a-Ge: Experimental determination of the interface response function using dynamic transmission electron microscopy. Journal of Applied Physics, 116(9), 093512(1-9).
The crystallization of amorphous semiconductors is a strongly exothermic process. Once initiated the release of latent heat can be sufficient to drive a self-sustaining crystallization front through the material in a manner that has been described as explosive. Here, we perform a quantitative in situ study of explosive crystallization in amorphous germanium using dynamic transmission electron microscopy. Direct observations of the speed of the explosive crystallization front as it evolves along a laser-imprinted temperature gradient are used to experimentally determine the complete interface response function (i.e., the temperature-dependent front propagation speed) for this process, which reaches a peak of 16 m/s. Fitting to the Frenkel-Wilson kinetic law demonstrates that the diffusivity of the material locally/immediately in advance of the explosive crystallization front is inconsistent with those of a liquid phase. This result suggests a modification to the liquid-mediated mechanism commonly used to describe this process that replaces the phase change at the leading amorphous-liquid interface with a change in bonding character (from covalent to metallic) occurring in the hot amorphous material.
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|Item Type:||Journal Article|
|Divisions:||Current > Schools > School of Chemistry, Physics & Mechanical Engineering
Current > QUT Faculties and Divisions > Science & Engineering Faculty
|Copyright Owner:||Copyright 2014 American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics.|
|Copyright Statement:||The following article appeared in Journal of Applied Physics, 116(9), 093512. and may be found at http://scitation.aip.org/content/aip/journal/jap/116/9/10.1063/1.4894397|
|Deposited On:||04 Nov 2015 23:26|
|Last Modified:||06 Nov 2015 05:03|
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