Theoretical Investigation of Current Instabilities and Terahertz Oscillations ina Two-Dimensional Electron Fluid

摘要

The purpose of this work is to develop further the theory of novel mechanisms forgeneration and detection of electromagnetic radiation in the terahertz range using the plasma oscillations of the two dimensional electron fluid in a Field Effect Transistor (FET). We have shown previously that the motion of electrons in a FET under certain conditions is described by hydrodynamic equations which coincide with those for shallow water, and that the current carrying state is unstable against plasma wave generation in the terahertz frequency range. In this work we have performed extensive numerical simulations of the strongly non-linear regime of plasma oscillations build up as a result of this instability. We have found highly regular non-linear oscillations related to traveling voltage jumps which are analogous to the so called hydraulic jumps in shallow water, or shock waves in a gas. (2)Proposed and studied the possibilities of using a FET as a tunable resonant terahertz detector, mixer and multiplier. Preliminary experiments performed at relatively low (tens of GHz) frequencies have confirmed our theoretical predictions.