Electric and magnetic field effects on the excitonic properties of elliptic core–multishell quantum wires

Abstract

Abstract. The effect of eccentricity distortions of core-multishell quantum wires on their electron, hole and exciton states is theoretically investigated. Within the effective mass approximation, the Schrödinger equation is numerically solved for electrons and holes in systems with single and double radial heterostructures, and the exciton binding energy is calculated by means of a variational approach. We show that the energy spectrum of a core-multishell heterostructure with eccentricity distortions, as well as its magnetic field dependence, are very sensitive to the direction of an externally applied electric field, an effect that can be used to identify the eccentricity of the system. For a double heterostructure, the eccentricities of the inner and outer shells play an important role on the excitonic binding energy, specially in the presence of external magnetic fields, and lead to drastic modifications in the oscillator strength.PACS numbers: 78.67. Lt, Electric and magnetic field effects on excitons in core-multishell quantum wires 2

Magnetic field induced shell-to-core confinement transition in type-II semiconductor quantum wires

“…14,15 Previous papers in the literature have theoretically demonstrated that the main effect of such hexagonal geometry was an increase of the carriers concentration around the corners of the hexagonal confining shell. 16 Similar effect is also observed for an elliptic shell, where carriers concentrate in the regions of higher curvature; 17,18 (ii) Heavy hole-Light hole coupling and band mixing effects are neglected-this is an usual and fair approximation 19,20 that simplifies a lot the calculations, by avoiding the need to diagonalize a valence band matrix, which is a very time consuming procedure; (iii) The dielectric mismatch effect between the different layers and between the outmost shell and the vacuum are neglected. In fact, the former is not expected to have a significant contribution, since this effect is proportional to 1 À 1 = 2 , 21 where 1 and 2 are the dielectric constants of the Si core and Si 0.7 Ge 0.3 shell, respectively, which are very similar.…”

Modeling of anisotropic properties of double quantum rings by the terahertz laser field

“…In other words, the laser field creates an anisotropy in the confinement potential, which can be continuously controlled by the THz laser field. It is useful to compare our results with those for elliptic core–multishell quantum wires 40 and CDQRs 41 . In these works, the anisotropy was induced by the geometry of the structure, that needs to be controlled during the growth process 40 or by effective mass 41 manipulations.…”

A finite-difference technique for computation of electron states in core–shell quantum wires of different configurations

“…These devices have also gained much importance because their properties are tailorable, thanks to technological advances in controlled growth and fabrication [5,6]. The different geometries of such structures [7][8][9][10][11][12] and different material compositions [13][14][15][16] further add to the novelty in their performance. The distinctive difference in their properties from those of bulk structures is due to the quantization of energy states [17,18], and hence characteristically different density states.…”