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Density functional simulations of Sb-rich GeSbTe phase change alloys
S Gabardi1, S Caravati, M Bernasconi
1Dipartimento di Scienza dei Materiali, Università di Milano-Bicocca, Milano, Italy.
Journal of Physics. Condensed Matter : an Institute of Physics Journal
|September 5, 2012
Summary
We modeled amorphous germanium-antimony-tellurium (GeSbTe) phase change alloys. Sb-rich compositions show localized high-frequency phonons and semiconducting properties with a 0.7-1.0 eV band gap.
Area of Science:
- Materials Science
- Computational Materials Science
- Solid State Physics
Background:
- Germanium-antimony-tellurium (GeSbTe) alloys are crucial phase change materials.
- Understanding the amorphous phase is key to optimizing their properties.
- Previous studies focused mainly on Ge(2)Sb(2)Te(5).
Purpose of the Study:
- To model the amorphous phase of Sb-rich GeSbTe alloys.
- To investigate the effect of composition on structural, vibrational, and electronic properties.
- To compare Sb-rich compositions with the well-studied Ge(2)Sb(2)Te(5).
Main Methods:
- Density functional molecular dynamics simulations.
- Quenching from the melt to generate amorphous structures.
- Analysis of structural, vibrational, and electronic properties.
Main Results:
- Generated amorphous models for Ge(1)Sb(1)Te(1) and Ge(2)Sb(4)Te(5).
- Observed high-frequency phonons (>200 cm(-1)) localized around Ge atoms.
- All amorphous alloys exhibited semiconducting behavior with a band gap of 0.7-1.0 eV.
Conclusions:
- Alloy composition influences the structural properties of the amorphous phase.
- Phonon localization in Ge-centered tetrahedra is consistent across studied compositions.
- Sb-rich GeSbTe alloys maintain semiconducting properties in their amorphous state.
