University of Botswana, Botswana
pp. 170 - 173
Keywords: photoionization, confining potentials, quantum dot
A theoretical investigation of the effects of the hill-like and the cup-like parabolic electric confining potentials on the photoionization cross section (PCS) in a spheroidal quantum dot are presented. The cup-like parabolic potential intensifies, the peak of the PCS becomes red-shifted for the sp transition, and becomes blue-shifted for the pd, df (and so forth) transitions. The hill-like potential, on the contrary, blue shifts the peaks of the PCS for the sp transitions, while it red-shifts those of transitions between higher states. Consequently, the two potentials discriminate between transitions involving the ground states and those involving higher states. This introduces selective tunability in nano devices, wherein the beam energy of operation may be increased or decreased as desired, without necessarily having to alter the dimensions of the quantum dot. Furthermore, in cases where the beam energies of excitation for transitions involving different states (e.g. sp, pd, df and so forth) are clustered around each other, appropriate utilization of either of these potentials can separate the energies of excitations, eliminating a situation whereby a beam with a minute spread of energy may excite electrons in both the ground state and the excited states.