Impurity breakdown in GaAs samples grown by molecular beam epitaxy

In this work we present studies for the behavior of impurity breakdown of t wo GaAs samples grown by Molecular Beam Epitaxy at 200 degrees C and 300 de grees C. We vary the temperature and the illumination intensity. For the sa mple grown at 200 degrees C, the transport mechanism after the breakdown is of the same type of the main free carriers at low electric fields. Below 1 00K, a clear dependence of the threshold electric field with temperature wa s observed. The sample grown at 300 degrees C shows a breakdown due to an a cceptor level at 41meV from the valence band. The threshold electric field 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.