Excitons in near surface quantum wells: Local probe of semiconductor/vacuum surface

We have investigated experimentally (by photoluminescence and photoluminescence excitation spectroscopy at 4.2 K) and theoretically the ground and excited exciton states in near-surface InGaAs/GaAs quantum wells (QWs) in perpendicular magnetic fields up to 14 T. The evolution of the exciton states in the magnetic field and with the decrease of thickness of the cap barrier layer between the QW and vacuum has been shown to be strongly influenced by the high vacuum potential barrier and by the abrupt, one order of magnitude. decrease of the dielectric constant on the semiconductor/vacuum surface. The peculiarities of the Stark effect in a perpendicular near-surface electric field have been analyzed. These effects can be used for the local probe of the near-surface electric field.