Solitary-wave conduction in p-type Ge under time-dependent voltage bias

We present the results of numerical simulations of a drift-diffusion model—including electric-field-dependent generation-recombination processes—for closely compensated p-type Ge at low temperature and under dc+ac and dc+noise voltage biases, with an Ohmic boundary condition. We observe frequency locking and quasiperiodicity under dc+ac bias, but do not find chaotic behavior for a uniform impurity profile. Noise-induced intermittent switching near the onset of solitary-wave conduction is compared to experimentally observed intermittency, type-III intermittency, and on-off intermittency. For a linearly increasing acceptor concentration, we find that the size of the solitary waves diminishes as they advance across the sample. © 1996 The American Physical Society.