High-field charge transport and noise in p-Si from first principles

TL;DR

This study uses first-principles calculations to accurately predict high-field charge transport and noise in p-type silicon, providing a rigorous test of electron-phonon interaction theories at various temperatures and electric fields.

Contribution

It presents the first comprehensive first-principles analysis of high-field hole mobility and noise in silicon, including anisotropy and energy relaxation effects at cryogenic temperatures.

Findings

Quantitative agreement with experimental mobility and PSD trends.

Correct prediction of energy relaxation time variation with electric field.

Highlights limitations due to valence band structure inaccuracies.

Abstract

The parameter-free computation of charge transport properties of semiconductors is now routine owing to advances in the ab-initio description of the electron-phonon interaction. Many studies focus on the low-field regime in which the carrier temperature equals the lattice temperature and the current power spectral density (PSD) is proportional to the mobility. The calculation of high-field transport and noise properties offers a stricter test of the theory as these relations no longer hold, yet few such calculations have been reported. Here, we compute the high-field mobility and PSD of hot holes in silicon from first principles at temperatures of 77 and 300 K and electric fields up to 20 kV cm$^{-1}$ along various crystallographic axes. We find that the calculations quantitatively reproduce experimental trends including the anisotropy and electric-field dependence of hole mobility and PSD. The experimentally observed rapid variation of energy relaxation time with electric field at cryogenic temperatures is also correctly predicted. However, as in low-field studies, absolute quantitative agreement is in general lacking, a discrepancy that has been attributed to inaccuracies in the calculated valence band structure. Our work highlights the use of high-field transport and noise properties as a rigorous test of the theory of electron-phonon interactions in semiconductors.