Phase diagrams for periodically driven Gunn diodes

Abstract

A simulation model of the electron transfer mechanism for bulk negative differential conductivity in n-GaAs is applied to investigate the formation and propagation of subsequent high field domains in the presence of an external microwave field. Phase diagrams for the distribution of modes are drawn for two different values of the non-equivalent intervalley relaxation time. The domain mode is found to entrain with the microwave signal in a variety of different frequency-locked solutions. At higher microwave amplitudes, period-doubling and other forms of mode-converting bifurcations take place. In this region, spatio-temporal chaos may also be observed, as indicated by a positive value of the largest Lyapunov exponent. At still higher amplitudes, transitions to delayed, quenched, and limited space charge accumulation modes occur. The D q -curve characterizing the multifractal structure is calculated for a typical chaotic solution.