Negative effective mass mechanism of negative differential drift velocity and terahertz generation

Abstract

The negative-differential-drift-velocity instability, which forms the basis of Gunn high-frequency generators, can originate from Ridley-Watkins-Hilsum or negative effective mass (NEM) mechanisms. The first mechanism is dissipative by nature. The second is mainly drift-related. Therefore, the second mechanism promises to be more effective. We show the existence of stationary oscillatory regimes in the ballistic NEM p + p p +-diodes, which have a base in the form of a periodic system of parallel p-type quantum-well channels with base length up to 30 nm. An oscillation frequency, which depends on the base length, doping, and spatial period, as well as loads and voltage across the diode, ranges from 1 to 5 THz. We propose an additional combined quantum GaAs-AlGaAsheterostructure, which can be overgrown on a cleaved edge of a specially grown wafer. This structure is intended to obtain electron dispersion relations with NEM sections in the useful energy range of 0.1-0.25 eV.

The Bloch Electron Response to Electric Fields: Application to Graphene

“…[34,39] As a point of emphasis, we note that the inertial effective mass becomes quite central in studies concerning complex quasiparticle formation [40,41] and for terahertz electromagnetic field generation. [42,43] Recent progress in attosecond technology has provided fine resolution on ultrashort time scales, which offers the potential for observing time-dependent inertial effective mass effects in graphene, as well as possible electrically induced electromagnetic field generation, due to carrier acceleration in the electric fields.…”

THz coherent lensless imaging

“…A microwave oscillator is created by applying a DC voltage to bias the device into its negative resistance region. Gunn diodes based on gallium arsenide are made for frequencies up to 200 GHz, while those relying on gallium nitride can reach up to 3 THz [64,65]. As these devices operate at room temperature in CW mode emitting monochromatic radiation in the range of 0.1-1 THz (from here on referred to as "sub-THz radiation"), they are suitable sources for coherent imaging.…”

The Microwave Sources for EPR Spectroscopy

“…Thanks to its simple construction and an ability to generate oscillations at very high frequencies, it is used in many systems. Diodes based on gallium arsenide are able to generate radiation at a frequency reaching 200 GHz, while frequency reachable by the diodes based on gallium nitride can be as high as 3 THz [12]. Moreover, Gunn generators are tunable in a wide frequency range [13].…”