Long term storage of inversion holes at a superlattice/GaAs interface

We report an investigation of the long term retention characteristic of a hole inversion layer at the interface between an AlAs/GaAs superlattice and GaAs in the dark. The retention time constant at 77 K is measured to be 34 h. From the temperature dependence of the retention time constant, an effective valence-band discontinuity of 0.17 eV is obtained.