Thermal transport is a key feature for the operation of phase change memory devices which rest on a fast and reversible transformation between the crystalline and amorphous phases of chalcogenide alloys upon Joule heating. In this paper we report on the ab initio calculations of bulk thermal conductivity of the prototypical phase change compounds Ge2Sb2Te5 and GeTe in their crystalline form. The related Sb2Te3 compound is also investigated for the sake of comparison. Thermal conductivity is obtained from the solution of the Boltzmann transport equation with phonon scattering rates computed within density functional perturbation theory. The calculations show that the large spread in the experimental data on the lattice thermal conductivity of GeTe is due to a variable content of Ge vacancies which at concentrations realized experimentally can halve the bulk thermal conductivity with respect to the ideal crystal. We show that the very low thermal conductivity of hexagonal Ge2Sb2Te5 of about 0.45 Wm-1K-1 measured experimentally is also resulting from disorder in the form of a random distribution of Ge/Sb atoms in one sublattice.

Campi, D., Paulatto, L., Fugallo, G., Mauri, F., Bernasconi, M. (2017). First-principles calculation of lattice thermal conductivity in crystalline phase change materials: GeTe, Sb2 Te3, and Ge2 Sb2 Te5. PHYSICAL REVIEW. B, 95(2) [10.1103/PhysRevB.95.024311].

First-principles calculation of lattice thermal conductivity in crystalline phase change materials: GeTe, Sb2 Te3, and Ge2 Sb2 Te5

Campi, D;Bernasconi, M.
2017

Abstract

Thermal transport is a key feature for the operation of phase change memory devices which rest on a fast and reversible transformation between the crystalline and amorphous phases of chalcogenide alloys upon Joule heating. In this paper we report on the ab initio calculations of bulk thermal conductivity of the prototypical phase change compounds Ge2Sb2Te5 and GeTe in their crystalline form. The related Sb2Te3 compound is also investigated for the sake of comparison. Thermal conductivity is obtained from the solution of the Boltzmann transport equation with phonon scattering rates computed within density functional perturbation theory. The calculations show that the large spread in the experimental data on the lattice thermal conductivity of GeTe is due to a variable content of Ge vacancies which at concentrations realized experimentally can halve the bulk thermal conductivity with respect to the ideal crystal. We show that the very low thermal conductivity of hexagonal Ge2Sb2Te5 of about 0.45 Wm-1K-1 measured experimentally is also resulting from disorder in the form of a random distribution of Ge/Sb atoms in one sublattice.
Articolo in rivista - Articolo scientifico
phonons: thermal transport; ab-initio calculations; phase change materials;
English
2017
95
2
024311
partially_open
Campi, D., Paulatto, L., Fugallo, G., Mauri, F., Bernasconi, M. (2017). First-principles calculation of lattice thermal conductivity in crystalline phase change materials: GeTe, Sb2 Te3, and Ge2 Sb2 Te5. PHYSICAL REVIEW. B, 95(2) [10.1103/PhysRevB.95.024311].
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/10281/176625
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