Based on ab initio molecular dynamics simulations, we investigated the structural, electronic and vibrational properties of cubic and amorphous Ge2Sb2Te5 (GST) phase change material, focusing in particular on the effects of defects in stoichiometry on the electronic properties. It turned out Ge/Sb deficiencies (excess) in the cubic phase induce a shift of the Fermi level inside the valence (conduction) bands. In contrast, the amorphous network is flexible enough to accommodate defects in stoichiometry, keeping the Fermi level pinned at the center of the bandgap (at zero temperature). Changes in the structural and electronic properties induced by the use of hybrid functionals (HSE03, PBE0) instead of gradient corrected functionals (PBE) are addressed as well. Analysis of vibrational spectra and Debye-Waller factors of cubic and amorphous GST is also presented.

Caravati, S., Bernasconi, M., Kuhne, T., Krack, M., Parrinello, M. (2009). First-principles study of crystalline and amorphous Ge2Sb2Te5 and the effects of stoichiometric defects. JOURNAL OF PHYSICS. CONDENSED MATTER, 21(25), 255501 [10.1088/0953-8984/21/25/255501].

First-principles study of crystalline and amorphous Ge2Sb2Te5 and the effects of stoichiometric defects

BERNASCONI, MARCO;
2009

Abstract

Based on ab initio molecular dynamics simulations, we investigated the structural, electronic and vibrational properties of cubic and amorphous Ge2Sb2Te5 (GST) phase change material, focusing in particular on the effects of defects in stoichiometry on the electronic properties. It turned out Ge/Sb deficiencies (excess) in the cubic phase induce a shift of the Fermi level inside the valence (conduction) bands. In contrast, the amorphous network is flexible enough to accommodate defects in stoichiometry, keeping the Fermi level pinned at the center of the bandgap (at zero temperature). Changes in the structural and electronic properties induced by the use of hybrid functionals (HSE03, PBE0) instead of gradient corrected functionals (PBE) are addressed as well. Analysis of vibrational spectra and Debye-Waller factors of cubic and amorphous GST is also presented.
Articolo in rivista - Articolo scientifico
First principles calculations, phase change materials
English
255501
Caravati, S., Bernasconi, M., Kuhne, T., Krack, M., Parrinello, M. (2009). First-principles study of crystalline and amorphous Ge2Sb2Te5 and the effects of stoichiometric defects. JOURNAL OF PHYSICS. CONDENSED MATTER, 21(25), 255501 [10.1088/0953-8984/21/25/255501].
Caravati, S; Bernasconi, M; Kuhne, T; Krack, M; Parrinello, M
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/10281/6149
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