Impurity photo-ionization cross section and stark shift of ground and two low-lying excited electron-states in a core/shell ellipsoidal quantum dot

A new investigation on photo-ionization cross section (PICS) of a donor impurity confined in a GaAs/AlGaAs core/shell elliptic quantum dots (CSEQDs) has been performed under electric field (EF) effect. By means of the finite element method (FEM), we have computed the binding energy (BE), oscillator strength Pif and PICS within the framework of the effective mass theory (EMT). Our numerical results reveal that the stark shift is greatly dependent on the strength of the EF, the degree of ellipticity β, and the states of electronic transitions. It can take positive or negative values depending on the situation. In addition, the photo-ionization describing the transition from the donor impurity ground-state (1simp) to one of the conduction sub-band states (1s0, 2s0, and 2p0) is affected by the shape of the quantum dots (QDs) and the EF. We demonstrated that varying internal and external parameters may control the photo-ionization cross-section. These characteristics can be exploited to fabricate optoelectronic devices like QD infrared photodetectors. [Display omitted] •The ground, the first and second excited states binding energies of on-center impurity are affected by the EF.•The dependence of the Stark shift of three low-lying electron transition states with on-center impurity on the electric field present a symmetric contribution.•The peaks of PICS are strongly affected by the EF and the shapes of GaAs/AlGaAs CSEQDs.•The prolate “CSEQD” shape has the strongest PICS amplitude of the 1simp-2p0 transition, with a notable blue-shift for this transition.•We recommend that future theoretical and experimental work focus on core–shell prolate QDs because the PICS have a higher magnitude in this case.