Transport and noise of of hot electrons in GaAs using an ab-initio-based semi-analytical model of two-phonon polar optical phonon scattering

Recent ab-initio studies of electron transport in GaAs have reported that electron-phonon 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 discrepancies remained in the power spectral density of current fluctuations (PSD). The high computational cost of the ab-initio approach necessitated various approximations, such as the neglect of off-shell terms, which may account for the discrepancy. Here, we report an ab-initio-based semi-analytical transport model of electron scattering by iterated interaction with two optical phonons via the Fröhlich mechanism, allowing many of the approximations in the ab-initio treatment to be lifted. We compare the calculated and experimental transport and noise properties as well as electron lifetimes as measured by photoluminescence experiments. We find quantitative agreement within 15% for the drift velocity and 25% for the Γ valley lifetimes, and agreement with the Γ-L intervalley lifetimes 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 PSD versus electric field is the formation of space charge domains rather than the intervalley scattering as has been assumed.