Optical and magneto optical responses assigned to probable processes of formation of exciton bound to an ionized donor in quantum dot

Abstract

The system formed by an electron and a hole coupled by Coulomb interactions with an ionized donor is the least known among the excitonic complexes. This complex is usually described as an exciton bound to an ionized donor. Strictly speaking, the exact mechanism of formation of this complex remains unclear. Two processes of formation giving rise to this system can be imagined. In a first process labeled A, the complex may be regarded as an exciton trapped by an ionized donor while in the second mechanism labeled B, this complex can be derived from the binding of a neutral donor and a hole. From a theoretical point of view both protocols can occur, with different probabilities and different binding energies, and consequently lead to different lines in the optical absorption spectra. In our hypothesis, we assume that the statistical mixture contains the two species coming from different origins and which were formed randomly. In this context of uncertainty and mixing processes, we propose to determine the absorption coefficient in the framework of the two possible hypotheses. In the aim to contribute with a valid description of the absorption spectrum, we report in this paper a full theoretical analysis of the optical and magneto-optical phenomena accompanying the two possible processes of formation, taking into account the dot sizes, the magnetic field strength, and the effect of the dielectric constant of the host material.