Modeling of electronic spectra and optical responses of a semiconductor AlGaAs/GaAs quantum well with three-step barriers: the role of external perturbations and impurity

Abstract

Multi-quantum barriers are of great importance in band engineering technologies and optoelectronics as they can build up quantum confinement via enhanced barrier heights. This theoretical study comprehensively investigated intersubband electronic and optical properties of an AlGaAs-based quantum well with three-step barriers. The electronic studies were performed within envelope wave functions and effective mass approximations under non-perturbative theory with hydrogenic donor impurity. The linear and the third-order nonlinear optical absorption coefficients and relative refractive index changes were examined under density matrix formalism taking into account a two-level system. Calculations were complicated to explore the role of externally applied static electric, magnetic and intense laser fields, and the donor impurity. The results showed an enhancement in the transition energies with incrementing all three external perturbations which is more impressive in the presence of a centrally positioned donor impurity. In the continue, the binding energies of donor impurity showed different affectability in the presence of external fields and the position of donor impurity. The binding energies were also found to be bigger as the donor impurity was localized at the highest probability of electron wave function. A blue-shift was detected in intersubband optical responses by enhancing all three applied fields in the presence and absence of donor impurity. The optical characteristics exhibited strongly decreased magnitudes after the addition of central impurity atom in both the presence and the absence of externally applied fields. Our findings provide a platform to design nonlinear devices for potential applications in optoelectronic technologies.