First-principles electron transport with phonon coupling: Large scale at low cost

Tue Gunst, Troels Markussen, Mattias L. N. Palsgaard, Kurt Stokbro, Mads Brandbyge

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Phonon-assisted tunneling plays a crucial role for electronic device performance and even more so with future size down-scaling. We show how one can include this effect in large-scale first-principles calculations using a single "special thermal displacement" (STD) of the atomic coordinates at almost the same cost as elastic transport calculations, by extending the recent method of Zacharias et al. [Phys. Rev. B 94, 075125 (2016)] to the important case of Landauer conductance. We apply the method to ultrascaled silicon devices and demonstrate the importance of phonon-assisted band-to-band and source-to-drain tunneling. In a diode the phonons lead to a rectification ratio suppression in good agreement with experiments, while in an ultrathin body transistor the phonons increase off currents by four orders of magnitude, and the subthreshold swing by a factor of 4, in agreement with perturbation theory.
Original languageEnglish
Article number161404
JournalPhysical Review B
Issue number16
Number of pages6
Publication statusPublished - 2017

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©2017 American Physical Society


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