Existence of tetrahedral site symmetry about Ge atoms in a single-crystal film of Ge2Sb2Te5 found by x-ray fluorescence holography

S. Hosokawa, T. Ozaki, K. Hayashi, N. Happo, M. Fujiwara, K. Horii, P. Fons, A. V. Kolobov, J. Tominaga

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Abstract

The authors discuss x-ray fluorescence holography (XFH) measurements taken from an epitaxial layer of the digital versatile disk random access memory (DVD-RAM) material Ge2Sb2Te5 grown on a single-crystal GaSb(100) substrate. By using fluorescent photons from the Ge atoms in the matrix, a three-dimensional atomic image was obtained around the Ge atoms in a Ge2Sb2Te5 film; details of the three-dimensional atomic arrangement will aim at clarification of the high-speed writing and erasing mechanism of the laser-induced crystal-amorphous phase transition in this DVD-RAM material. Analysis of the XFH images revealed that the epitaxial layer did not possess a hexagonal structure as in the equilibrium phase of Ge2Sb2Te5, but a cubic structure with tetrahedral site symmetry about Ge atoms, different from the previous powder diffraction result. The present structure may support the umbrella-flip model of the Ge atoms between the octahedral site in the distorted rocksalt crystal and the tetrahedral site in the amorphous phase on the laser-induced phase transition.

Original languageEnglish
Article number131913
JournalApplied Physics Letters
Volume90
Issue number13
DOIs
Publication statusPublished - 2007 Apr 8
Externally publishedYes

ASJC Scopus subject areas

  • Physics and Astronomy (miscellaneous)

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    Hosokawa, S., Ozaki, T., Hayashi, K., Happo, N., Fujiwara, M., Horii, K., Fons, P., Kolobov, A. V., & Tominaga, J. (2007). Existence of tetrahedral site symmetry about Ge atoms in a single-crystal film of Ge2Sb2Te5 found by x-ray fluorescence holography. Applied Physics Letters, 90(13), [131913]. https://doi.org/10.1063/1.2717094