Donor-impurity related photoionization cross section in GaAs / Ga 1 _-c^double quantum rings: Effects of geometry and hydrostatic pressure

The donor-impurity related photoionization cross section in GaAs/Ga1 _-x^AlxAs three-dimensional concentric double quantum rings is investigated. The photoionization cross section dependence on the incident photon energy is studied considering the effects of hydrostatic pressure, variations of aluminum concentration, geometries of the structure, and impurity position. The interpretation of the dipole matrix element, which reflects the photoionization probability, is also given. We have found that these parameters can lead to both redshift and blueshift of the photoionization spectrum and also influence the cross section peak value.