Polarizability of Exciton in Surface Quantum Well

Abstract

Surface quantum wells are seeking considerable attention due to their asymmetrical nature of polarized interface and its consequences. Their results with and without external perturbations are expected to be remarkably different from their counterparts in symmetrical quantum wells. Effect of electric field on binding energies of light hole and heavy hole exciton in surface quantum well composed of vacuum/GaAs/Ga1xAlxAs are theoretically calculated as a function of well width and Al composition. Effect of image charges arising due to the mismatch of the dielectric constant at the vacuum/GaAs interface is considered. Stark shift and polarizability of exciton in this surface quantum well is also calculated for various strengths of electric field with different well width confinement as well as Al concentration. Our results show that: (1) exciton binding energy increases as the electric field applied along the growth axis increases; (2) stark shift in exciton energy decreases as electric field, Al composition and well width increase; and (3) polarizability of exciton decreases when the electric field increases, but increases when well width increases. Variation of our results with those for other symmetrical wells will provide a choice of the well for electric field applications.