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Title: Preferred orientation of nanoscale order at the surface of amorphous Ge{sub 2}Sb{sub 2}Te{sub 5} films

We report evidence that as-deposited amorphous Ge{sub 2}Sb{sub 2}Te{sub 5} thin films contain nanoscale clusters that exhibit a preferred orientation, attributed to the earliest stages of heterogeneous nucleation. Fluctuation transmission electron microscopy reveals structural order in the samples, but (220)-related contributions are suppressed. When homogeneous nucleation is promoted via electron bombardment, the sample remains diffraction amorphous but the (220) contribution appears. We simulated data for randomly oriented nanoscale order using ab initio molecular-dynamics models of Ge{sub 2}Sb{sub 2}Te{sub 5}. The simulated (220) contribution always has larger magnitude than higher-order signals; thus, the lack of the experimental signal indicates a significant preferred orientation.
Authors:
;  [1] ;  [2] ; ;  [3]
  1. Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, 1304 W. Green St., Urbana, Illinois 61801 (United States)
  2. (United States)
  3. Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW (United Kingdom)
Publication Date:
OSTI Identifier:
22254053
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 103; Journal Issue: 20; Other Information: (c) 2013 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
77 NANOSCIENCE AND NANOTECHNOLOGY; DIFFRACTION; ELECTRON BEAMS; FLUCTUATIONS; GRAIN ORIENTATION; MOLECULAR DYNAMICS METHOD; NANOSTRUCTURES; NUCLEATION; SIGNALS; SIMULATION; THIN FILMS; TRANSMISSION ELECTRON MICROSCOPY