Excitons in a surface quantum well

• Exciton binding energies in a Surface Quantum Well (SQW) are calculated.
• Effects of non-parabolicity and image charges are considered.
• Charge carriers are repelled by the image charge at the single vacuum/GaAs interface only.
• Binding energies are significantly reduced, when image charges are included.
• Deadlayer in a SQW is smaller compared to semi-infinite solids.

Binding energies of excitons in a Surface Quantum Well (SQW) composed of vacuum/GaAs/AlxGa1−xAs as a function of wellwidth are calculated. The effect of non-parabolicity is considered by using an energy dependent effective mass. The effect of mass anisotropy and the effect of image charges which arise due to the large dielectric discontinuity at the vacuum/GaAs interface are also considered. The average distances of the electron 〈ze〉 and the hole 〈zh〉 from the vacuum/GaAs interface, with and without image charges and the integrated probability of finding an electron and a hole inside the well are also calculated. The results agree well with the available experimental data.