PHOTOELECTRICAL MEMORY IN GAAS ALGAAS MULTILAYER QUANTUM-WELL STRUCTURES/

An increase in the dark current (by 2-3 orders of magnitude) in GaAs/A lxGa1-xAs multilayer quantum-well structures with x similar or equal t o 0.4 is observed after illumination of the structures with optical li ght (lambda < 1.3 mu m). This increase is sustained for an extended ti me (more than 10(3) s) at low temperatures. It then decreases to its i nitial value upon heating of the sample. A model of the barrier with l ocal sag of the conduction band facilitating tunneling is proposed. Th e conduction band sag and the magnitude of the current grow due to opt ical ionization of uncontrolled deep level clusters present in the bar rier and decrease due to subsequent capture of electrons from the cond uction band by the deep levels upon heating. (C) 1998 American Institu te of Physics.