Journal Article

PreJuSER-5915

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Experimentally constrained density-functional calculations of the amorphous structure of the prototypical phase-change material Ge2Sb2Te5

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/2128/11029  doi:10.1103/PhysRevB.80.020201

Abstract: Phase change materials involve the rapid and reversible transition between nanoscale amorphous (a-) and crystalline (c-) spots in a polycrystalline film and play major roles in the multimedia world, including nonvolatile computer memory. The materials of choice are alloys of Ge, Sb, and Te, e.g., Ge2Sb2Te5 (GST) in digital versatile disk-random access memory. There has been much speculation about the structure of a- GST, but no model has yet received general acceptance. Here we optimize the structure by combining the results of density-functional calculations with high-energy x-ray diffraction data and x-ray photoelectron spectroscopy (XPS) measurements of the electronic densities of states to determine the structure. The structure agrees very well with available experimental data, including the differences in the XPS data between the amorphous and crystalline structures.

Keyword(s): J ; amorphous state (auto) ; antimony alloys (auto) ; crystallisation (auto) ; density functional theory (auto) ; electronic density of states (auto) ; germanium alloys (auto) ; metallic thin films (auto) ; phase change materials (auto) ; random-access storage (auto) ; tellurium alloys (auto) ; X-ray diffraction (auto) ; X-ray photoelectron spectra (auto)

Note: The experimental work was supported by the Japan Science and Technology Agency, and the calculations were performed on IBM BlueGene/L, BlueGene/P, and p690 computers in the Forschungszentrum Julich with grants from the FZ Julich and the John von Neumann Institute for Computing. R.O.J. thanks SPring-8 and its staff for hospitality and support during a research visit.

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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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