TITLE

Amorphous structure melt-quenched from defective GeSbTe

AUTHOR(S)
Sun, Zhimei
PUB. DATE
November 2012
SOURCE
Journal of Materials Science;Nov2012, Vol. 47 Issue 21, p7635
SOURCE TYPE
Academic Journal
DOC. TYPE
Article
ABSTRACT
GeSbTe (GST) is a technologically important phase-change material for data storage, where the fast reversible phase transition between crystalline and amorphous states is used for recording information. The encoding is achieved by the large contrast in physical properties between the two states. Ge vacancies (V) and Sb antisite atoms (Sb) are primary point defects in crystalline GST. The effect of V and Sb on the atomic arrangements in amorphous GST is unknown, which, however, has significant effects on the performance of GST. In this work, by means of ab initio molecular dynamics calculations, the atomic arrangements in amorphous ideal and defective GST have been investigated. The results show that the amorphous structure of GST with Sb ( St-GST) or with V ( V-GST) has the same cubic framework and close chemical ordering to ideal GST, and hence similar fast reversible phase transition behavior is expected in the defective phases. Furthermore, the presence of Sb or V in the crystalline phase will result in much more Ge atoms in a tetrahedral geometry as well as in a fourfold octahedral environment in the amorphous state. Especially in V-GST, around 36 % Ge atoms occupy a fourfold octahedral geometry. As fourfold octahedral Ge atoms can enhance the large contrast in physical properties between the crystalline and amorphous phases, introducing Ge vacancies would be an efficient way to improve the performance of GST phase-change materials.
ACCESSION #
78437610

 

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