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Defects in amorphous phase-change materials

Published online by Cambridge University Press:  09 May 2013

Jennifer Luckas ,
Daniel Krebs ,
Stephanie Grothe ,
Josef Klomfaß ,
Reinhard Carius ,
Christophe Longeaud  and
Matthias Wuttig
Jennifer Luckas
Affiliation:
I. Physikalisches Institut, RWTH Aachen University, 52056 Aachen, Germany; and Laboratoire de Génie Electrique de Paris (CNRS UMR 8507), Supelec, Universités Paris VI et XI, Plateau de Moulon, 91190 Gif sur Yvette, France
Daniel Krebs
Affiliation:
IBM Zürich Research Laboratory, 8803 Rüschlikon, Switzerland
Stephanie Grothe
Affiliation:
I. Physikalisches Institut, RWTH Aachen University, 52056 Aachen, Germany
Josef Klomfaß
Affiliation:
IEF-5 Photovoltaik, Forschungszentrum Jülich, 52425 Jülich, Germany
Reinhard Carius
Affiliation:
IEF-5 Photovoltaik, Forschungszentrum Jülich, 52425 Jülich, Germany
Christophe Longeaud
Affiliation:
Laboratoire de Génie Electrique de Paris (CNRS UMR 8507), Supelec, Universités Paris VI et XI, Plateau de Moulon, 91190 Gif sur Yvette, France
Matthias Wuttig*
Affiliation:
I. Physikalisches Institut, RWTH Aachen University, 52056 Aachen, Germany; and JARA Fundamentals of Future Information Technology, RWTH Aachen University, 52056 Aachen, Germany
*
a)Address all correspondence to this author. e-mail: [email protected]
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Abstract

Understanding the physical origin of threshold switching and resistance drift phenomena is necessary for making a breakthrough in the performance of low-cost nanoscale technologies related to nonvolatile phase-change memories. Even though both phenomena of threshold switching and resistance drift are often attributed to localized states in the band gap, the distribution of defect states in amorphous phase-change materials (PCMs) has not received so far, the level of attention that it merits. This work presents an experimental study of defects in amorphous PCMs using modulated photocurrent experiments and photothermal deflection spectroscopy. This study of electrically switching alloys involving germanium (Ge), antimony (Sb) and tellurium (Te) such as amorphous germanium telluride (a-GeTe), a-Ge15Te85 and a-Ge2Sb2Te5 demonstrates that those compositions showing a high electrical threshold field also show a high defect density. This result supports a mechanism of recombination and field-induced generation driving threshold switching in amorphous chalcogenides. Furthermore, this work provides strong experimental evidence for complex trap kinetics during resistance drift. This work reports annihilation of deep states and an increase in shallow defect density accompanied by band gap widening in aged a-GeTe thin films.

Type
Invited Feature Paper
Information
Journal of Materials Research , Volume 28 , Issue 9 , 14 May 2013 , pp. 1139 - 1147
Copyright
Copyright © Materials Research Society 2013 

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References

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