1. Phonon-assisted tunneling in direct-bandgap semiconductors.
- Author
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Mohammed, Mazharuddin, Verhulst, Anne S., Verreck, Devin, Van de Put, Maarten L., Magnus, Wim, Sorée, Bart, and Groeseneken, Guido
- Subjects
TUNNEL field-effect transistors ,QUANTUM tunneling ,PHONONS ,BAND gaps ,SEMICONDUCTORS ,ELECTRON-phonon interactions - Abstract
In tunnel field-effect transistors, trap-assisted tunneling (TAT) is one of the probable causes for degraded subthreshold swing. The accurate quantum-mechanical (QM) assessment of TAT currents also requires a QM treatment of phonon-assisted tunneling (PAT) currents. Therefore, we present a multi-band PAT current formalism within the framework of the quantum transmitting boundary method. An envelope function approximation is used to construct the electron-phonon coupling terms corresponding to local Fröhlich-based phonon-assisted inter-band tunneling in direct-bandgap III-V semiconductors. The PAT current density is studied in up to 100 nm long and 20 nm wide p-n diodes with the 2- and 15-band material description of our formalism. We observe an inefficient electron-phonon coupling across the tunneling junction. We further demonstrate the dependence of PAT currents on the device length, for our non-self-consistent formalism which neglects changes in the electron distribution function caused by the electron-phonon coupling. Finally, we discuss the differences in doping dependence between direct band-to-band tunneling and PAT current. [ABSTRACT FROM AUTHOR]
- Published
- 2019
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