Thermoactivated conductivity in p-GaAs/Al0.5Ga0.5As below 5 k under combined influence of illumination and uniaxial stress

Strongly thermoactivated negative photoconductivity in p-GaAs/Al 0.5 Ga 0.5 As doped with Be is observed under the combined influence of illumination by a red light emitting diode and uniaxial compression at liquid helium temperatures. The effect can be described in a model with deep donor-like traps at the heterointerface below the Fermi level, if a barrier between the ground and excited donor-like states E B = 6 meV is introduced. The barrier does not depend on uniaxial stress that governs the strong resistivity on temperature dependence mainly by the reduction of 2D hole concentration and 2D hole mobility both in dark and under illumination.