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Atomic stacking and van-der-Waals bonding in GeTe–Sb2Te3 superlattices

Published online by Cambridge University Press:  27 September 2016

Jamo Momand ,
Felix R.L. Lange ,
Ruining Wang ,
Jos E. Boschker ,
Marcel A. Verheijen ,
Raffaella Calarco ,
Matthias Wuttig  and
Bart J. Kooi
Jamo Momand*
Affiliation:
Zernike Institute for Advanced Materials, University of Groningen, 9747 AG Groningen, The Netherlands
Felix R.L. Lange
Affiliation:
I. Physikalisches Institut (IA), RWTH Aachen University, 52056 Aachen, Germany; and JARA-Institut Green IT, Forschungszentrum Jülich GmbH and RWTH Aachen University, 52056 Aachen, Germany
Ruining Wang
Affiliation:
Department of Epitaxy, Paul-Drude-Institut für Festkörperelektronik, 10117 Berlin, Germany
Jos E. Boschker
Affiliation:
Department of Epitaxy, Paul-Drude-Institut für Festkörperelektronik, 10117 Berlin, Germany
Marcel A. Verheijen
Affiliation:
Eindhoven University of Technology, Department of Applied Physics, NL-5600 MB Eindhoven, The Netherlands
Raffaella Calarco
Affiliation:
Department of Epitaxy, Paul-Drude-Institut für Festkörperelektronik, 10117 Berlin, Germany
Matthias Wuttig
Affiliation:
I. Physikalisches Institut (IA), RWTH Aachen University, 52056 Aachen, Germany; and JARA-Institut Green IT, JARA-FIT, Forschungszentrum Jülich GmbH and RWTH Aachen University, 52056 Aachen, Germany
Bart J. Kooi*
Affiliation:
Zernike Institute for Advanced Materials, University of Groningen, 9747 AG Groningen, The Netherlands
*
a) Address all correspondence to these authors. e-mail: j.momand@rug.nl
b) e-mail: b.j.kooi@rug.nl
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Abstract

GeTe–Sb2Te3 superlattices have attracted major interest in the field of phase-change memories due to their improved properties compared with their mixed counterparts. However, their crystal structure and resistance-switching mechanism are currently not clearly understood. In this work epitaxial GeTe–Sb2Te3 superlattices have been grown with different techniques and were thoroughly investigated to unravel the structure of their crystalline state with particular focus on atomic stacking and van-der-Waals bonding. It is found that, due to the bonding anisotropy of GeTe and Sb2Te3, the materials intermix to form van-der-Waals heterostructures of Sb2Te3 and stable GeSbTe. Moreover, it is found through annealing experiments that intermixing is stronger for higher temperatures. The resulting ground state structure contradicts the dominant ab-initio results in the literature, requiring revisions of the proposed switching mechanisms. Overall, these findings shed light on the bonding nature of GeTe–Sb2Te3 superlattices and open a way to the understanding of their functionality.

Keywords

crystal growthepitaxybonding
Type
Invited Feature Papers
Information
Journal of Materials Research , Volume 31 , Issue 20 , 28 October 2016 , pp. 3115 - 3124
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Copyright
Copyright © Materials Research Society 2016 

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References

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