Illumination stimulated persistent channel depletion at selectively doped Al0.3Ga0.7As/GaAs interface

The results of the combined influence of illumination and negative substrate bias on the conductance at Al0.3Ga0.7As/GaAs interface are reported. The observed strong (two to three orders of magnitude) persistent increase in sample resistance is explained with a model of two conducting layers in the heterostructure: (1) an interface channel and (2) a low mobility AlGaAs layer. The simultaneous application of light and substrate bias leads to the generation of electrons and holes, their separation, and their subsequent capture by traps. A counterfield remaining in the sample after the removal of both influences causes a strong persistent channel depetion and an increase of the resistance.