Current filamentation in n-GaAs thin films with different contact geometries

We investigate current filamentation in n-GaAs in the regime of low-tempera ture impurity breakdown for different sample and contact geometries. Comput er simulations based on a dynamic microscopic model are compared with spati ally resolved measurements in thin epitaxial layers. By varying the applied bias, load resistance and magnetic field, one can effectively control the shape and the size of the filaments in rectangular samples with two point c ontacts. Multistability and hysteresis due to the successive symmetry-break ing formation of multiple filaments are found in Corbino discs upon sweep-u p and sweep-down of the voltage and explained by our model.