Kavli Affiliate: Austin J. Minnich
| First 5 Authors: Benjamin Hatanpää, Austin J. Minnich, , ,
| Summary:
Ab-initio calculations of charge transport properties in materials without
adjustable parameters have provided microscopic insights into electron-phonon
interactions which govern charge transport properties. Other transport
properties such as the diffusion coefficient provide additional microscopic
information and are readily accessible experimentally, but few ab-initio
calculations of these properties have been performed. Here, we report
first-principles calculations of the hot electron diffusion coefficient in Si
and its dependence on electric field over temperatures from 77 — 300 K. While
qualitative agreement in trends such as anisotropy at high electric fields is
obtained, the quantitative agreement that is routinely achieved for low-field
mobility is lacking. We examine whether the discrepancy can be attributed to an
inaccurate description of f-type intervalley scattering by computing the
microwave-frequency noise spectrum and piezoresistivity. These calculations
indicate that any error in the strength of f-type scattering is insufficient to
explain the diffusion coefficient discrepancies. Our findings suggest that the
measured diffusion coefficient is influenced by factors such as space charge
effects which are not included in ab-initio calculations, impacting the
interpretation of this property in terms of charge transport processes.
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