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Phase Change in (GeTe)1-x(Sb2Te3)x Investigated by Hard X-ray Photoemission Spectroscopy

Published online by Cambridge University Press:  01 February 2011

Keisuke Kobayashi ,
Jung-Jin Kim ,
Toshiyuki Matsunaga ,
Kouichi Kifune ,
Eiji Ikenaga ,
Masaaki Kobata ,
Shigonori Ueda ,
Rie Kojima  and
Noboru Yamada
Keisuke Kobayashi
Affiliation:
koba_kei@spring8.or.jp, national Institute for Materials Science, Beamline Station, Kouto 1-1-1,, Sayo-cho, CO, 679-5198, Japan, +81 791 58 082 PHS 3386, *81 791 58 0223
Jung-Jin Kim
Affiliation:
jungjin2007.kim@samsung.com, Japan Synchrotron Radiation Research Institute, Spring 8, 1-1-1 Kouto, Sayo-Cho, Hyogo, 679-5198, Japan
Toshiyuki Matsunaga
Affiliation:
matsunaga.toshiyuki@jp.panasonic.com, Matsushita Electric Industry Co. Ltd., Characterization Technology Group, Materials Science and Analysis Technology Center, 3-1-1 Yagumo- Nakamachi,, Moriguchi, Osaka, 570-8501, Japan
Kouichi Kifune
Affiliation:
lucky\_jungjin@yahoo.co.kr, Osaka Prefecture University, Faculty of Liberal Arts and Sciences, 1-1 Gakuen-cho, Sakai, Osaka, 599-8531, Japan
Eiji Ikenaga
Affiliation:
ikenaga@spring8.or.jp, Japan Synchrotron Radiation Research Institute, Spring 8, 1-1-1 Kouto, Sayo-Cho, Hyogo, 679-5198, Japan
Masaaki Kobata
Affiliation:
m-kobata@spring8.or.jp, National Institute for Materials Science, Spring 8, 1-1-1 Kouto, Sayo-Cho, Hyogo, 679-5148, Japan
Shigonori Ueda
Affiliation:
uedas@spring8.or.jp, National Institute for Materials Science, Spring 8, 1-1-1 Kouto, Sayo-Cho, Hyogo, 679-5148, Japan
Rie Kojima
Affiliation:
yamada.noboru@jp.panasonic.com, Matsushita Electric Industrial Co., Ltd., AV Core Technology Development Center, 3-1-1 Yagumo- Nakamachi, Moriguchi, Moriguchi, Osaka, 570-8501, Japan
Noboru Yamada
Affiliation:
yamada.noboru@jp.panasonic.com, Matsushita Electric Industrial Co., Ltd., AV Core Technology Development Center, 3-1-1 Yagumo- Nakamachi, Moriguchi, Moriguchi, Osaka, 570-8501, Japan
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Abstract

The mechanism of the fast reversible change between the amorphous and crystalline phases in (GeTe)1−x(Sb2Te3)x (GST) has not yet been fully understood. The crystalline phase has been identified as having a NaCl-type cubic structure with random occupation of the A sites by Ge, Sb and vacancies, and 100% occupation of B sites by Te. This fact calls our attention to a possible close relation to the inherent crystal bonding instability observed for the average five valence electrons (<5>) family. We present here the results of systematic hard X-ray photoemission experiments on GST films with various compositions in both the amorphous and crystalline phases, and discuss that a similar chemical bonding instability does indeed play an essential role in the phase change mechanism in GST. We propose a model for the fast phase change, in which 6 fold to 3 fold transition of p-like bonding play an essential role, in this class of materials.

Keywords

photoemissionelectronic structurememory
Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 1072: Symposium G – Phase-Change Materials for Reconfigurable Electronics and Memory Applications , 2008 , 1072-G02-07
Copyright
Copyright © Materials Research Society 2008

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References

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