Journal
MATERIALS TODAY PHYSICS
Volume 19, Issue -, Pages -Publisher
ELSEVIER
DOI: 10.1016/j.mtphys.2021.100412
Keywords
Thermoelectrics; Electron transport; Wigner distribution; Narrow gap semiconductors; ab-initio simulations
Funding
- Star-Friedman Fund for Promising Scientific Research
- Harvard Quantum Initiative
- STC Center for Integrated Quantum Materials
- NSF [DMR-1231319]
- Harvard FAS Research Computing
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This study introduces a new first principles electronic transport model that includes contributions from interband coupling and off-diagonal components, aiming to explain electronic transport behavior in narrow gap semiconductors. Experimental results show that interband tunneling dominates the electron transport dynamics at low doping concentrations.
Electronic transport in narrow gap semiconductors is characterized by spontaneous vertical transitions between carriers in the valence and conduction bands, a phenomenon also known as Zener tunneling. However, this effect is not captured by existing models based on the Boltzmann transport equation. In this work, we propose a new fully first principles model for electronic transport using the Wigner distribution function and implement it to solve the equations of motion for electrons. The formalism generalizes the Boltzmann equation to materials with strong interband coupling and include transport contributions from off-diagonal components of the charge current operator. We illustrate the method with a study of Bi2Se3, showing that interband tunneling dominates the electron transport dynamics at experimentally relevant small doping concentrations, a behavior that is likely shared with other semiconductors, including topological insulators. Surprisingly, Zener tunneling occurs also between band subvalleys separated by energy much larger than the band gap. (C) 2021 The Author(s). Published by Elsevier Ltd.
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