Nonlinear dependence of the magnetophotoluminescence energies of asymmetric GaAs/Ga0.67Al0.33As quantum wells on an external magnetic field

Nonlinear dependence of the magnetophotoluminescence (MPL) energies in modulation-doped asymmetric GaAs/Ga0.67Al0.33As quantum wells of different widths are investigated experimentally and theoretically as functions of an external magnetic field. The investigated structures have only one electric subband populated with electrons. Contrary to the theoretical descriptions existing in the literature and based on the oscillations of screening, the observed maxima of MPL energies do not occur at integer filling factors and do not change into minima for higher well widths. We interpret our observations assuming that the oscillations of MPL energies are due to an oscillatory electron transfer between a GaAs well and a reservoir outside the well. We obtain a very good description of the experimental data concerning both the maxima positions and the oscillation amplitudes for different well widths and electron densities. Our interpretation is corroborated by the quantum Hall data obtained on the same samples.