Low temperature breakdown and current filamentation in n-type GaAs with homogeneous and partially ordered Si doping

We present an experimental and theoretical study of the breakdown caused by impurity impact ionization in n-GaAs. The observed difference in the electric field strengths for the breakdown threshold and the bistability regime between homogeneous and partially ordered doping with Si donors is explained and confirmed by numerical simulations, applying a weighted ensemble Monte Carlo method in the case of the inhomogeneous problem. Furthermore, conditions for the appearance of hysteresis loops are experimentally investigated as a function of load resistance and sample width. The transitions between different branches of the current-voltage characteristics can be understood as switching between homogeneous states and current filaments in good agreement with theoretical predictions on the basis of a simple generation-recombination model.