Multistability of the current-voltage characteristics in doped GaAs-AlAs superlattices

Electric-field domain formation in doped semiconductor superlattices leads to sharp discontinuities in the current-voltage (I-V) characteristic. The successive expansion of the high-field region with increasing bias voltage through the periodic heterostructure manifests itself in a regular sequence of stable current branches. The current shows a complex hysteretic behavior. We observe two, three, and more stable current levels for fixed bias voltages. Calculations of the I-V characteristic based on a microscopic model support the experimentally observed multistability.