Abstract

Hydrodynamic instabilities in two-dimensional electron flow in ungated semiconductors are studied here. The driving force for the electrons is an imposed voltage difference that generates a unidimensional electric field inside the semiconductor and its surroundings. The governing equations are linearized for small perturbations around the steady-flow solution. The eigenvalue spectrum determining the rates of growth and wave numbers of the oscillations is calculated. The electron flow undergoes oscillatory instability and becomes more unstable as the voltage difference is increased. The results show that it is possible to obtain oscillation frequencies of the order of terahertz, indicating the possibility of radiative power at this frequency. © 2009 American Institute of Physics.