We demonstrate that the electron density of a remotely doped GaAs/AlxGa1-xAs quantum well is reduced by continuous illumination, for both photon energies above and below the barrier bandgap. For the latter case we show the depletion is due to the creation of a photovoltage across the GaAs buffer layer deeper in the structure. This results in the electron density determined directly from photoluminescence spectra being significantly lower than that deduced from Hall or Shubnikov-de Haas measurements, either with or without illumination. References: 20
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