CHAOTIC CURRENT OSCILLATIONS IN THE GUNN-EFFECT DEVICE UNDER THE DC AND THE RF BIAS VOLTAGES

A one-dimensional model system of the Gunn-effect device is considered. It consists of an n+-n-n+ GaAs sandwich structure where the high-n+ contact layers on both ends are linearly graded to the uniformly distributed low-n bulk region and a half-wave sinusoidal doping notch is incorporated near the cathode. Using the finite differece method, spatio-temporal evolution of the system subject to the dc and the rf-alternating fields is computed with the amplitudes and the frequency being taken as the control parameters. Current oscillations associated with the cyclic traveling high-electric-field domain are shown to materialize over a range of the control parameters. In particular, the current oscillations become chaotic at specially chosen values of these bias parameters.