Anharmonic Quantum Transport Analysis of Thermal Transport Anomalies in Ultrathin Silicon Nanowires
Abstract
Thermal transport in low-dimensional semiconductors is important for nanoelectronics, quantum devices, and thermoelectrics. Recent molecular dynamics (MD) studies reveal a nonmonotonic diameter dependence of thermal conductivity in ultrathin silicon nanowires (NWs), but classical MD is limited at low temperatures and under strong confinement. Here, we investigate this anomaly using anharmonic non-equilibrium Green's function (NEGF) simulations combined with density functional theory-trained neuroevolution potentials. All transport results are expressed as effective thermal conductivities (κeff) for NW devices with a finite channel length of L=10 nm. At 300 K, κeff decreases with diameter to minima at 6.24 and 5.50 nm for [001]- and [110]-oriented NWs, respectively. At 10 K, the corresponding minima occur at 7.33 and 5.50 nm. At room temperature, dominant momentum-conserving normal scattering relative to Umklapp processes enables Poiseuille-like hydrodynamic phonon flow that competes with boundary scattering. At cryogenic temperatures, Bose--Einstein statistics restrict heat transport to low-frequency confined acoustic-like modes. Comparison with the harmonic Landauer limit reveals a finite correction to κeff from anharmonic phonon--phonon scattering. Classical MD neglects quantum suppression and overexcites high-frequency vibrations, leading to overestimated thermal conductivity in thinner, strongly confined NWs at low temperatures. The NEGF framework incorporates quantum statistics and anharmonic scattering, providing a quantum-mechanical description of thermal transport down to 10 K.
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BibTeX
@misc{patra2026anharmonic,
title = {{Anharmonic Quantum Transport Analysis of Thermal Transport Anomalies in Ultrathin Silicon Nanowires}},
author = {Lokanath Patra and Mayur Pratap Singh and Satish Kumar},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2605.26529},
eprint = {2605.26529},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2605.26529},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Anharmonic Quantum Transport Analysis of Thermal Transport Anomalies in Ultrathin Silicon Nanowires
AU - Lokanath Patra
AU - Mayur Pratap Singh
AU - Satish Kumar
PY - 2026
DA - 2026/10/06
PB - arXiv
DO - 10.48550/arxiv.2605.26529
UR - https://arxiv.org/abs/2605.26529
AB - Thermal transport in low-dimensional semiconductors is important for nanoelectronics, quantum devices, and thermoelectrics. Recent molecular dynamics (MD) studies reveal a nonmonotonic diameter dependence of thermal conductivity in ultrathin silicon nanowires (NWs), but classical MD is limited at low temperatures and under strong confinement. Here, we investigate this anomaly using anharmonic non-equilibrium Green's function (NEGF) simulations combined with density functional theory-trained neuroevolution potentials. All transport results are expressed as effective thermal conductivities (κ_eff) for NW devices with a finite channel length of L=10 nm. At 300 K, κ_eff decreases with diameter to minima at 6.24 and 5.50 nm for [001]- and [110]-oriented NWs, respectively. At 10 K, the corresponding minima occur at 7.33 and 5.50 nm. At room temperature, dominant momentum-conserving normal scattering relative to Umklapp processes enables Poiseuille-like hydrodynamic phonon flow that competes with boundary scattering. At cryogenic temperatures, Bose--Einstein statistics restrict heat transport to low-frequency confined acoustic-like modes. Comparison with the harmonic Landauer limit reveals a finite correction to κ_eff from anharmonic phonon--phonon scattering. Classical MD neglects quantum suppression and overexcites high-frequency vibrations, leading to overestimated thermal conductivity in thinner, strongly confined NWs at low temperatures. The NEGF framework incorporates quantum statistics and anharmonic scattering, providing a quantum-mechanical description of thermal transport down to 10 K.
ER -