Lattice Thermal Conductivity of mGeTe•nSb2Te3 Phase-Change Materials: A First-Principles Study

• Published in: Crystals (Basel) Vol. 9; no. 3; p. 136
• Main Authors: Pan, Yuanchun, Li, Zhen, Guo, Zhonglu
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 07-03-2019
• Subjects: Bonding strength; Data storage; Experiments; First principles; Heat conductivity; Heat transfer; lattice thermal conductivity; Lattice vacancies; Memory devices; mGeTe•nSb2Te3; Phase change materials; Phase transitions; Size effects; Thermal conductivity; Thermodynamic properties; Transport properties; Transport theory
• ISSN: 2073-4352; 2073-4352
• DOI: 10.3390/cryst9030136

As the most promising materials for phase-change data storage, the pseudobinary mGeTe•nSb2Te3 (GST) chalcogenides have been widely investigated. Nevertheless, an in-depth understanding of the thermal-transport property of GST is still lacking, which is important to achieve overall good performance of the memory devices. Herein, by using first-principles calculations and Boltzmann transport theory, we have systematically studied the lattice thermal conductivity along the out of plane direction of both stable hexagonal and meta-stable rock-salt-like phases of GST, and good agreement with available experiments has been observed. It is revealed that with the increase of the n/m ratio, the lattice thermal conductivity of hexagonal GST increases due to the large contribution from the weak Te-Te bonding, while an inverse trend is observed in meta-stable GST, which is due to the increased number of vacancies that results in the decrease of the lattice thermal conductivity. The size effect on thermal conductivity is also discussed. Our results provide useful information to manipulate the thermal property of GST phase-change materials.