Kavli Affiliate: Austin J. Minnich
| First 5 Authors: Peishi S. Cheng, Shi-Ning Sun, Alexander Y. Choi, Austin J. Minnich,
| Summary:
High-field charge transport in semiconductors is of fundamental interest and
practical importance. While the ab initio treatment of low-field transport is
well-developed, the treatment of high-field transport is much less so,
particularly for multi-phonon processes that are reported to be relevant in
GaAs. Here, we report a calculation of the high-field transport properties and
power spectral density (PSD) of hot electrons in GaAs from first principles
including on-shell two-phonon (2ph) scattering. The on-shell 2ph scattering
rates are found to qualitatively alter the high-field distribution function by
increasing both the momentum and energy relaxation rates as well as
contributing markedly to intervalley scattering. This finding reconciles a
long-standing discrepancy regarding the strength of intervalley scattering in
GaAs as inferred from transport and optical studies. The characteristic
non-monotonic trend of PSD with electric field is not predicted at this level
of theory, indicating that off-shell 2ph or other processes play a fundamental
role in high-field transport. This observation highlights how ab initio
calculations of PSD may be used as a stringent test of the electron-phonon
interaction in semiconductors.
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