Microscopic analysis of noise and nonlinear dynamics in p-type germanium

We analyze the impurity breakdown in p-type germanium at liquid-helium temperature on a microscopic level. By using a Monte Carlo simulation including capture and impact ionization processes from shallow impurities, the field-dependent trapping and generation rates are calculated. The current noise is investigated within a two-step process: thermal noise is obtained directly from the Monte Carlo simulation and generation-recombination noise is obtained from a two-level model using the calculated transition rates. In the region close to the phase transition between a nonconducting and a conducting state, various scenarios of nonlinear dynamics related to the dynamical Hall effect have been found.