Optical and electronic properties of a singly ionized double donor confined in coupled quantum dot-rings

Electronic and singly ionized double donor states confined in a GaAs-A1GaAs coupled quantum dot-ring were calculated. The proposed model fits the geometry of realistic coupled quantum dot rings and allows studying the evolution of the energy spectrum as a function of the height/width of the quantum dot or ring, or the quantum ring mean radius separately. This feature allows us to successfully test/compare the energy spectra with limit cases such as single-electron two-dimensional quantum rings and dots. The results show that the electron and singly ionized double donor states strongly depend on the coupled quantum dot-ring's geometry and external probes, such as hydrostatic pressure and crossed electric/magnetic fields, sample temperature, and aluminum concentration. In addition, the linear, nonlinear, and total optical coefficients were calculated within the two-level density matrix formalism as a function of the parameters previously mentioned. The results show that the singly ionized double donor coupled quantum dot-ring is optically active within the range of 20-90 meV, whose absorption peak can be coarsely (finely) tuned by changing the quantum dot height/width (quantum ring height/radius, the external probes, or the aluminum concentration). Alternatively, changing the quantum ring width allows the absorption peak to be tuned into the THz band.

Automated summary

This study calculated the electronic and singly ionized double donor states in a GaAs-A1GaAs coupled quantum dot-ring. The proposed model accurately captures the geometry of realistic coupled quantum dot rings and allows for the study of the energy spectrum as a function of various parameters. The results demonstrate the strong dependence of the electron and singly ionized double donor states on the geometry of the coupled quantum dot-ring and external probes.