Forcing of chaos in semiconductor superlattices

The chaotic behavior of high-field transport in weakly-coupled narrow-miniband GaAs/AlAs superlattices (SL) under ac + dc biases has been numerically studied within a self-consistent discrete model. It is shown that the regions of entrainment and quasiperiodicity form the Arnol'd tongues on the driving frequency–driving amplitude parameter plane. Chaos is demonstrated to appear at the boundaries of the tongues and in the regions where they overlap. Numerical simulation shows that ac driving can lead to chaos for different regimes: (i) when the electric-field domains in the SL are stable; and (ii) when they are unstable (periodically oscillating).