Transport and noise of hot electrons in GaAs using a semianalytical model of two-phonon polar optical phonon scattering

Abstract

Recent ab initio studies of electron transport in GaAs have reported that electron-phonon (e-ph) interactions beyond the lowest order play a fundamental role in charge transport and noise phenomena. Inclusion of the next-leading-order process in which an electron scatters with two phonons was found to yield good agreement for the high-field drift velocity, but the characteristic nonmonotonic trend of the power spectral density of current fluctuations (PSD) with electric field was not predicted. The high computational cost of the ab initio approach necessitated various approximations to the two-phonon scattering term, which were suggested as possible origins of the discrepancy. Here we report a semianalytical transport model of two-phonon electron scattering via the Fröhlich mechanism, allowing a number of the approximations in the ab initio treatment to be lifted while retaining the accuracy to within a few percent. We compare the calculated and experimental transport and noise properties as well as scattering rates measured by photoluminescence experiments. We find quantitative agreement within 15% for the drift velocity and 25% for the Γ valley scattering rates, and agreement with the Γ−L intervalley scattering rates within a factor of two. Considering these results and prior studies of current noise in GaAs, we conclude that the most probable origin of the nonmonotonic PSD trend versus electric field is the formation of space-charge domains rather than intervalley scattering as has been assumed.

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