期刊
PHYSICAL REVIEW B
卷 98, 期 20, 页码 -出版社
AMER PHYSICAL SOC
DOI: 10.1103/PhysRevB.98.205202
关键词
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资金
- Science Foundation Ireland (SFI) [15/IA/3160]
- Science Foundation Ireland (SFI) [15/IA/3160] Funding Source: Science Foundation Ireland (SFI)
We present an ab initio study that identifies the main electron-phonon scattering channels in n-type PbTe. We develop an electronic transport model based on the Boltzmann transport equation within the transport relaxation time approximation, fully parametrized from first-principles calculations that accurately describe the dispersion of the electronic bands near the band gap. Our computed electronic mobility as a function of temperature and carrier concentration is in good agreement with experiments. We show that longitudinal optical phonon scattering dominates electronic transport in n-type PbTe, while acoustic phonon scattering is relatively weak. We find that scattering due to soft transverse optical phonons is by far the weakest scattering mechanism, due to the symmetry-forbidden scattering between the conduction band minima and the zone center soft modes. Soft phonons thus play the key role in the high thermoelectric figure of merit of n-type PbTe: they do not degrade its electronic transport properties although they strongly suppress the lattice thermal conductivity. Our results suggest that materials like PbTe with soft modes that are weakly coupled with the electronic states relevant for transport may be promising candidates for efficient thermoelectric materials.
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