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Issue 25, 2017
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Dynamic reconfiguration of van der Waals gaps within GeTe–Sb2Te3 based superlattices

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Abstract

Phase-change materials based on GeSbTe show unique switchable optoelectronic properties and are an important contender for next-generation non-volatile memories. Moreover, they recently received considerable scientific interest, because it is found that a vacancy ordering process is responsible for both an electronic metal–insulator transition and a structural cubic-to-trigonal transition. GeTe–Sb2Te3 based superlattices, or specifically their interfaces, provide an interesting platform for the study of GeSbTe alloys. In this work such superlattices have been grown with molecular beam epitaxy and they have been characterized extensively with transmission electron microscopy and X-ray diffraction. It is shown that the van der Waals gaps in these superlattices, which result from vacancy ordering, are mobile and reconfigure through the film using bi-layer defects and Ge diffusion upon annealing. Moreover, it is shown that for an average composition that is close to GeSb2Te4 a large portion of 9-layered van der Waals systems is formed, suggesting that still a substantial amount of random vacancies must be present within the trigonal GeSbTe layers. Overall these results illuminate the structural organization of van der Waals gaps commonly encountered in GeSbTe alloys, which are intimately related to their electronic properties and the metal–insulator transition.

Graphical abstract: Dynamic reconfiguration of van der Waals gaps within GeTe–Sb2Te3 based superlattices

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Publication details

The article was received on 08 Mar 2017, accepted on 09 Jun 2017 and first published on 12 Jun 2017


Article type: Paper
DOI: 10.1039/C7NR01684K
Citation: Nanoscale, 2017,9, 8774-8780
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    Dynamic reconfiguration of van der Waals gaps within GeTe–Sb2Te3 based superlattices

    J. Momand, R. Wang, J. E. Boschker, M. A. Verheijen, R. Calarco and B. J. Kooi, Nanoscale, 2017, 9, 8774
    DOI: 10.1039/C7NR01684K

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