Impurity Breakdown in GaAs Samples Grown by Molecular Beam Epitaxy

In this work we present studies for the behavior of impurity breakdown of two GaAs samples grown by Molecular Beam Epitaxy at 200oC and 300oC. We vary the temperature and the illumination intensity. For the sample grown at 200oC, the transport mechanism after the breakdown is of the same type of the main free carriers at low electric elds. Below 100K, a clear dependence of the threshold electric eld with temperature was observed. The sample grown at 300oC shows a breakdown due to an acceptor level at 41meV from the valence band. The threshold electric eld increases with illumination due to the generation of free electrons by deep levels. A similar behavior was also observed for a Cr doped GaAs sample.