Pattern Transition and Chaos in Nonlinear Semiconductors

We study the dyamical behavior of the stationary electric-field domains in the Gunn diode under periodically driving at a fixed driving frequency. We find interesting pattern transitions: type-I rocking domain→type-I hybrid domain→type-II rocking domain→type-II hybrid domain as the amplitude of the a c bias varies. The type-II rocking and the type-II hybrid domains exhibit period-doubling route to chaos and fully chaotic behavior, respectively. The multi-domain formation can also be found in the type-II domains. The evolution of the electric-field domains and the bifurcation processes will be given in detail.