Effects of temperature, hydrostatic pressure, and aluminum concentration on the electro-optical properties of a D2+ molecular complex in elliptical GaAs/GaAlAs nanoflakes

The electro-optical properties, i.e., the optical response in the presence of a static electric field of a D 2 + molecular complex (two charge centers interacting with a conduction band electron)confined in self-assembled GaAs/GaAlAs flake-like quantum dots were calculated. Within the effective mass approximation, the calculated results were successfully contrasted with analytic and numerical results for neutral donors and single electrons in strictly two-dimensional quantum dots. The electro-optical properties were calculated within the density matrix formalism in the two-level approximation since the electric field breaks the degeneracy between the ground and first excited states when the two charge centers do not collectivize the electron. The results show that an increase in a hydrostatic pressure field, in the in-situ temperature, and the aluminum concentration in the host material can tune the total absorption peak leading to redshifts (with the former probe) and blueshifts (with the other physical quantities). Suitable donor-donor separation and polarization angle values can maximize the absorption peak value. In addition, the asymmetry due to the shrinkage of the nanoflake’s top and its eccentricity can enhance the D 2 + /optical field coupling and make this system optically active for energies below ≈ 20 meV (Terahertz band).