Electron correlations in quasi-2D structures at high magnetic fields in the presence of embedded donor impurities

Abstract Systematic far infrared (FIR) magneto-spectroscopic studies have been carried out on a series of GaAs / AlGaAs multiple quantum well (QW) structures, δ -doped with Si donors in both well and barrier centers. Filling-factor ( ν )-dependent energy blueshifts of the many-electron singlet-like transition have been observed in the integer and fractional Quantum Hall regime. For all samples studied the blueshift of this transition decreases with increasing B for ν − ) ions, is understood in the context of exact diagonalization studies of a donor and confined electrons. Our results show that FIR magneto-optical excitations of the system depend sensitively on the microscopic electron configuration in the vicinity of the positive donor ions due to electron correlations and localization at high magnetic fields.