Electronic structure of on- and off-center hydrogenic impurities in quantum dots and quantum nanowires: energies and dipole polarizability

Abstract

The energy levels, ground state binding energies, and electric dipole polarizabilities of hydrogenic impurities in quantum dots and quantum nanowires have been investigated using a non-relativistic B-spline based variational method. Firstly, we have worked on the characterization of those impurities (donor/electron) in quantum dots and quantum nanowires, considering the two cases where the impurity is centered or off-centered in the nanostructure. Secondly, the electric dipole polarizabilities have been computed and their sensitivity with confinement parameters investigated. So the energies, binding energies, and dipole polarizabilities were reported for the centered and the off-centered donor and electron impurities as a function of the cavity radius and the off-center displacement. We found that the polarization of the studied system greatly depends on the model potential form, the off-center displacement, and the cavity radius. In the case of quantum dots and for the parabolic potential, the convergence of the polarizability for large values of the quantum size is shown. For the quantum nanowire case, we have shown that the polarizability is greater in the case of the z axis displacement than that of the transversal one. This leads to the fact that the system is more polarizable when the impurity is moved along the z axis than the transversal one.

Shape and quantum size effects on the electronic structure, oscillator strengths and state lifetimes of helium-like quantum dots

“…Two-electron quantum dots with or without Helium-like impurities have received a lot of attention. This kind of system can be considered as the simplest quantum dot system with impurities which, unlike hydrogenic impurities [8][9][10], exhibits many-body interaction effects. Several theoretical studies have been devoted to the studies of the electronic properties of two-electron quantum dots.…”

Oscillator strengths, transition probabilities and state lifetimes of on- and off-center donor impurities in quantum dots: off-center displacement, quantum size and potential-shape effects

“…The optoelectronic properties of these nanoscale devices (electronic structure, electric polarizabilities, oscillator strengths, etc.) are strongly linked to their shape, size and composition [3][4][5][6]. This makes them very promising confinement quantum structures for the manufacturing of a broad range a e-mail: biglingui@gmail.com (corresponding author) b e-mail: omotapon@univ-douala.com of new technological equipment such as electro-optic modulators, inter-band lasers and solar cells, to mention few [7].…”

“…This paper deals with optical properties of hydrogenic impurities in quantum dots, especially oscillator strengths, transition probabilities and states lifetimes. In this work, we aim to investigate particularly the off-center displacement effects combined to that of the shape and size of the quantum dot on their properties, by the use of the model potential suggested by Zhu et al [4] and employed by Melingui Melono et al [6]. The appropriate definition of the parameters of this model potential allows us to configure the quantum dot shape.…”

“…J. D (2021) 75 :110 approach followed, which is derived from the one used in our previous works [6,23], relies on a B-splines-based variational method. In the limit of centered hydrogenic impurity (that is near zero displacement) with an infinite potential type, our results are found to be in good agreements with previous ones in the literature.…”

Oscillator strengths, transition probabilities and state lifetimes of hydrogen atom confined in spherical cavity: off-center displacement effects

“…Since the pioneering works of Michels et al (1937) [1] followed by the work of Sommerfeld et al (1938) [2] and the posterior works [3][4][5][6], it is known that the confinement modifies the properties of atomic, ionic or molecular systems (orbitals, energy levels, localization of electrons, filling of shells). The characterization of the optical and electronic properties of confined systems finds applications in various domains as the study of impurities in semiconductors and nanostructures like spherical and cylindrical quantum dots and quantum nanowires [7][8][9][10], atoms or molecules trapped in zeolite cavity [11,12], atoms and molecules confined in fullerene cavity [13][14][15][16], to mention few. Several books have reviewed the relevant contributions in terms of information, detailed discussions on numerical or theoretical methods as well as applications of quantum confined systems [17][18][19].…”