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Title: Theory of Thermal Relaxation of Electrons in Semiconductors

Abstract

We compute the transient dynamics of phonons in contact with high energy ``hot'' charge carriers in 12 polar and non-polar semiconductors, using a first-principles Boltzmann transport framework. For most materials, we find that the decay in electronic temperature departs significantly from a single-exponential model at times ranging from 1 ps to 15 ps after electronic excitation, a phenomenon concomitant with the appearance of non-thermal vibrational modes. We demonstrate that these effects result from the slow thermalization within the phonon subsystem, caused by the large heterogeneity in the timescales of electron-phonon and phonon-phonon interactions in these materials. We propose a generalized 2-temperature model accounting for the phonon thermalization as a limiting step of electron-phonon thermalization, which captures the full thermal relaxation of hot electrons and holes in semiconductors. A direct consequence of our findings is that, for semiconductors, information about the spectral distribution of electron-phonon and phonon-phonon coupling can be extracted from the multi-exponential behavior of the electronic temperature.

Authors:
; ;
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1427544
DOE Contract Number:  
AC02-06CH11357
Resource Type:
Journal Article
Journal Name:
Physical Review Letters
Additional Journal Information:
Journal Volume: 119; Journal Issue: 13; Journal ID: ISSN 0031-9007
Publisher:
American Physical Society (APS)
Country of Publication:
United States
Language:
English

Citation Formats

Sadasivam, Sridhar, Chan, Maria K. Y., and Darancet, Pierre. Theory of Thermal Relaxation of Electrons in Semiconductors. United States: N. p., 2017. Web. doi:10.1103/PhysRevLett.119.136602.
Sadasivam, Sridhar, Chan, Maria K. Y., & Darancet, Pierre. Theory of Thermal Relaxation of Electrons in Semiconductors. United States. doi:10.1103/PhysRevLett.119.136602.
Sadasivam, Sridhar, Chan, Maria K. Y., and Darancet, Pierre. Fri . "Theory of Thermal Relaxation of Electrons in Semiconductors". United States. doi:10.1103/PhysRevLett.119.136602.
@article{osti_1427544,
title = {Theory of Thermal Relaxation of Electrons in Semiconductors},
author = {Sadasivam, Sridhar and Chan, Maria K. Y. and Darancet, Pierre},
abstractNote = {We compute the transient dynamics of phonons in contact with high energy ``hot'' charge carriers in 12 polar and non-polar semiconductors, using a first-principles Boltzmann transport framework. For most materials, we find that the decay in electronic temperature departs significantly from a single-exponential model at times ranging from 1 ps to 15 ps after electronic excitation, a phenomenon concomitant with the appearance of non-thermal vibrational modes. We demonstrate that these effects result from the slow thermalization within the phonon subsystem, caused by the large heterogeneity in the timescales of electron-phonon and phonon-phonon interactions in these materials. We propose a generalized 2-temperature model accounting for the phonon thermalization as a limiting step of electron-phonon thermalization, which captures the full thermal relaxation of hot electrons and holes in semiconductors. A direct consequence of our findings is that, for semiconductors, information about the spectral distribution of electron-phonon and phonon-phonon coupling can be extracted from the multi-exponential behavior of the electronic temperature.},
doi = {10.1103/PhysRevLett.119.136602},
journal = {Physical Review Letters},
issn = {0031-9007},
number = 13,
volume = 119,
place = {United States},
year = {2017},
month = {9}
}