Asymmetry effects on the electro-optical properties of a hydrogen molecular ion in vertically coupled InAs/GaAs quantum dots: Spatial finite element method calculations

Abstract

Geometrical asymmetry effects of vertically coupled InAs/GaAs quantum dots (disks, cones, and lenses) confining a hydrogen molecular ion in growth-directed magnetic, tilted electric, and in-plane optical fields are investigated. The impact of non-equal heights/base sizes and misalignment of quantum dots on the energy spectrum and total optical absorption (calculated via compact density matrix formalism) is discussed. Quantum disk (cones) configurations are found to be more stable (unstable). The absorption response is improved by favoring in-plane electron mobility, achievable with small-height QDs, growth-directed magnetic fields, larger base sizes, or misaligned dots. Results show that disk geometries have the highest optical response, followed by lenses and cones. A wide tunability range of $14\mathrm{meV}-80\mathrm{meV}$ is reported by applying a tilted electric field, with energy spectra and dipole moments dependent on its inclination angle (distinctive dot geometry fingerprints).