Relaxation of low-temperature negative photoconductivity in p-GaAs/Al_0.5Ga_0.5As under normal and uniaxially stressed conditions

Abstract

The study of transient relaxation processes of photoconductivity in p GaAs/Al_0.5Ga_0.5As:Be in the dark after illumination has been undertaken for verification of the previously proposed model for explanation of low-temperature thermoactivated photoconductivity in these heterostructures. Relaxa-tions of 2D hole concentration at a different magnitude of uniaxial stress show strong temperature dependence and may be well described in terms of kinetic phenomena developed for materials with deep centers, which give an opportunity for thermoactivation barrier E _B evolution. The magnitude E _B=2±0.3 meV, which was calculated from experimental data, is well comparable with E _B=3±0.5 meV obtained previously from dynamic equilibrium measurements under illumination and does not reveal dependence on uniaxial stress.

Keywords:

• GaAs/Al_1−x Ga_1−x As
• Uniaxial compression
• Negative photoconductivity

Acknowledgements

The work was supported by RFBR (grant 04-02-16861) and RFPGC (grant 5248.2006.2). We thank also Dr O.P. Hansen and Dr C.B. Sorensen for providing the heterostructures.