Entropy and electronic properties of an off-axis hydrogen-like impurity in non-uniform height quantum ribbon with structural and geometrical azimuthal potential barriers

Abstract

A systematic study of the energy structure and the entropy of a single electron and an off-axis donor impurity in a non-uniform height quantum ribbon with two geometrical peaks and two azimuthal potential barriers is presented. The system is subject to the joint action of an in-plane static electric field and threading magnetic field. By considering realistic atomic force microscopy images of droplet epitaxy quantum rings, the anisotropy in the rim height nanostructure has been modeled by including a phenomenological one-parametric harmonic function while its variable width was considered by including azimuthal potential barriers. The corresponding Schrodinger equation was solved by using a rigorous adiabatic approximation in order to decouple the slow rotation motion from fast axial one. This procedure allows us to obtain a one dimensional wave-equation with an effective potential. We show that the energy structure is a result of the strong competition between external probes, electron-donor Coulomb interaction and geometrical quantum wells. The results show that the randomness of the system is strongly dependent of the position both the donor impurity and the structural potential barriers as well as the orientation and the strength of the external electric field.