Discontinuities and hysteresis in the I-V characteristics of n-GaAs at lowtemperatures

We present experimental investigations of current filamentation in n-GaAs f ilms in the regime of low-temperature impurity breakdown. Using a laser-sca nning microscope, we were able to reconstruct current filaments in biasing regions of multistability. It is shown that discontinuities and hysteresis frequently observed in current-voltage characteristics are due to the inter action of filaments with material imperfections. In particular filaments re main in energetically unfavourable configurations when squeezed or pinned b y defects.