Abrupt changes in the capacitance between the p and n regions were observed
in a planar p-i-n GaAs/AlGaAs heterostructure with two tunneling-coupled q
uantum wells exposed to laser irradiation (lambda = 633 nm). These changes
can be caused by variations in both temperature (in the vicinity of T simil
ar to 2 K) and the dc voltage applied to the structure. A memory effect was
detected; this effect manifested itself in the long lifetime of anomalies
observed after the illumination had been turned off. Self-consistent calcul
ations of distributions of charge and electric field were performed for the
structures that contained a donor impurity in AlGaAs layers; this impurity
is responsible for origination of DX centers that give rise to persistent
photoconductivity. It is demonstrated that abrupt changes in capacitance ca
n occur in such a structure, and the values of the parameters required for
origination of these jumps are determined. (C) 2001 MAIK "Nauka/Interperiod
ica".