Journal Article

PreJuSER-5496

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Structure of amorphous Ge8Sb2Te11: GeTe-Sb2Te3 alloys and optical storage

Akola, J. ; Jones, R. O.FZJ*

2009
APS College Park, Md.

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Please use a persistent id in citations: http://hdl.handle.net/2128/11036  doi:10.1103/PhysRevB.79.134118

Abstract: The amorphous structure of Ge8Sb2Te11, an alloy used in the Blu-ray Disc, the de facto successor to digital versatile disk (DVD) optical storage, has been characterized by large-scale (630 atoms, 0.4 ns) density-functional/molecular-dynamics simulations using the new PBEsol approximation for the exchange-correlation energy functional. The geometry and electronic structure agree well with available x-ray diffraction data and photoelectron measurements. The total coordination numbers are Ge: 4.0, Sb: 3.7, and Te: 2.9, and the Ge-Ge partial coordination number is 0.7. Most atoms (particularly Sb) prefer octahedral coordination but 42% of Ge atoms are "tetrahedral." Structural details, including ring statistics, local coordination, and cavities (12% of total volume), are strikingly similar to those of Ge2Sb2Te5, which is used in DVD-random access memory. The presence of less than 10% Sb atoms leads to significant changes from GeTe.

Keyword(s): J ; amorphous semiconductors (auto) ; antimony compounds (auto) ; density functional theory (auto) ; digital versatile discs (auto) ; electronic structure (auto) ; germanium compounds (auto) ; molecular dynamics method (auto)

Note: The calculations were performed on IBM Blue Gene/P and p6 575 computers in the FZ Julich with grants from the FZJ and the John von Neumann Institute for Computing (NIC). We thank S. Kohara, K. Kobayashi, and Y. Tsuchiya for providing original data, and S. Kohara, T. Matsunaga, and N. Yamada for helpful discussions.

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Contributing Institute(s):

1. Quanten-Theorie der Materialien (IFF-1)

Research Program(s):

1. Kondensierte Materie (P54)

Appears in the scientific report 2009

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