Ballistic transport and terahertz electronics

The feature sizes of modern semiconductor devices have entered the range, where ballistic or quasi-ballistic transport is dominant. In this regime, conventional notions of electron mobility become invalid and the device impedance becomes an oscillatory function of frequency. Electron inertia plays an important role at high frequencies and/or in short devices and oscillations of the electron density in device channels enable a new generation of THz devices. Plasma wave THz detectors using oscillations of the electron density in device channels already outperform more conventional THz detectors but achieving their full potential of plasma wave electronics will require using “plasmonic crystals”, which might be implemented as 2D or 3D arrays of coherently operating plasmonic FETs.