Modulation of binding energy and polarizability in GaAs four-quantum-dot systems under electric fields

Abstract

The research explores the impact of an external electric field (E-field), the position of a shallow donor impurity, and key structural variables (including dot width and barrier width) on the binding energy (B.E.) and polarizability of a nanosystem. The system consists of an electron and a shallow donor impurity contained within four $GaAs$ quantum dots (4 GaAs QDs), which are infused in an ${Al}_x{Ga}_{1-x}As$ medium. To model these effects, the effective mass framework and finite element framework (FEF) are employed. The findings demonstrate that the electric field perturbs the symmetry of the binding energy, resulting in position-dependent variations that reflect the interplay between quantum confinement and field-induced electron delocalisation. In addition, variations in dot and barrier widths, combined with the impurity position, induce complex modifications in the binding energy. Strong confinement results in a nearly constant polarisability, whereas weak confinement produces a non-monotonic response. Furthermore, changes in barrier width and impurity position significantly affect the polarizability, highlighting the interaction between quantum confinement and field-induced charge redistribution.