Electron viscosity dispersion and terahertz and ultra-short pulse detection

Michael Shur

doi:10.1117/12.3005219

11 March 2024 Electron viscosity dispersion and terahertz and ultra-short pulse detection

Michael Shur

Proceedings Volume 12885, Terahertz, RF, Millimeter, and Submillimeter-Wave Technology and Applications XVII; 128850D (2024) https://doi.org/10.1117/12.3005219
Event: SPIE OPTO, 2024, San Francisco, California, United States

Abstract

The channel lengths of deep submicron transistors and photodetectors reached dimensions smaller than the mean free path. These devices could operate at frequencies comparable to or higher than the electron momentum collision frequency. Their ballistic and quasi-ballistic operation regimes are dramatically different from a more conventional collision-dominated transport. In these regimes, the measured apparent electron mobility becomes proportional to the channel length (so-called “ballistic mobility”). At high mobility values, the electron transport becomes viscous, and the electron density oscillations in ultra short channels are damped by the electronic viscosity rather than by the collisions with impurities or lattice vibrations. In this paper, we show that viscosity dispersion is an important effect in determining the effective viscosity at high frequencies and/or for very short excitation pulses. The characteristic frequency determining the viscosity dispersion is the electron-electron collision frequency, which depends on the electron concentration and temperature. Using a Drude-like equation for the viscosity, we evaluate the viscosity dispersion effect for deep submicron devices implemented in Si, AlGaN/ GaN, p-diamond, and AlGaAs/InGaAs. The applications of the viscosity dispersion effect include terahertz and IR photodetectors. This effect is especially important for the detection of femtosecond and terahertz pulses.

Conference Presentation

(2024) Published by SPIE. Downloading of the abstract is permitted for personal use only.

Citation Download Citation

Michael Shur "Electron viscosity dispersion and terahertz and ultra-short pulse detection", Proc. SPIE 12885, Terahertz, RF, Millimeter, and Submillimeter-Wave Technology and Applications XVII, 128850D (11 March 2024); https://doi.org/10.1117/12.3005219

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