Electronic spectrum in a quantum double CdS/β-HgS/H2O cylindrical wire

Abstract

The electronic spectrum in a cylindrical CdS/[3-HgS semiconductor heterosystem of the quantum wire type located in an H20 dielectric medium is investigated. In the energy interval where the levels of both potential wells merge, there is a repulsion effect on the levels (a "bottleneck" effect). The nonmonotonic dependence of the electron and hole spectra on the thickness of the 13-HgS film means that in experiments there is an instability of the energy position of the exciton lines in a certain frequency range.Semiconductor heterojunction structures on the nanometer scale are important objects of study in the physics of solids in connection with the possibility of using them in laser systems. The wide choice of materials and system geometries (symmetry, quantity, thickness, arrangement, etc., of the layers) allows one to prepare heterosystems which are unique in their properties with special properties qualitatively different from those which occur in uniform materials. There is significant interest in studies of quasi-one-dimensional (quantum wire) and zero-dimensional (quantum dot) heterostructures [1-5] since in these systems one can observe such unique optical and transport properties as increased optical nonlinearity and high conductivity for individual quasiparticles and collective excitations.Simple heterosystems have been investigated in the vast majority of the papers --semiconductor nanocrystals in a dielectric medium. However, in recent years experimental and theoretical papers have appeared in which not only complex (multilayer) planar heterosystems are studied [6] but also spherical ones [7,8]. In particular in [7] the spherical heterosystem CdS//~-HgS/CdS/H20 was experimentally created for which the main electron and exciton energy levels were studied as a function of the thicknesses of the films in the system. Since such a heterosystem can be created experimentally in the form of cylindrical wires superimposed on each other, there is interest in studying the electronic spectrum of such a quasi-onedimensional system. The aim of the present paper is to study the electronic spectrum in a cylindrical CdS/5-HgS/H20 nanoscale heterosystem.

Influence of the Lateral Electrostatic Field on the Statistical Distribution of Charge Carriers in a Cylindrical Nanolayer of β-HgS

“…All subsequent calculations will be carried out within the framework of the isotropic effective mass approximation. It will be considered that the valence band of the β-HgS semiconductor is split into subbands of light (lh) and heavy (hh) holes (see works [9,10,13,14,[17][18][19][20][21]). Table 1 lists some of the physical characteristics of bulk β-CdS and β-HgS crystals that are needed later.…”

“…Table 1. Some characteristics of bulk semiconductors β-CdS and β-HgS (data taken from publications [9,10,13,14,[17][18][19][20][21]. Here𝑚𝑚 0 is the free electron mass.…”

“…In the quantum mechanical aspect, they represent a nano radial barrier/well/barrier heterostructure with cylindrical symmetry. The most common and intensively studied of them are cylindrical nanocomposites β-CdS/ β-HgS/ β-CdS (see publications [9][10][11][12][13][14][15][16] and references therein). The interest of researchers in these heterophase structures is primarily due to the manifestation of a number of unique properties of metacinnabar under size quantization conditions.…”

“…From the applied point of view, for device applications, these structures will be more multifunctional than individual quantum films and quantum wires. In works [9,10], the energy spectrum of charge carriers in a layered cylindrical β-CdS/ β-HgS/ β-CdS heterostructure was calculated, and in work [13], the specifics of the conduction mechanism in such structures were considered. Raman scattering of electrons in a cylindrical layered β-CdS/β-HgS quantum dot is considered in work [12], and work [15] is devoted to studying the effect of hydrostatic pressure and temperature factor on the diamagnetic properties of the electron subsystem in a β-CdS/β-HgS cylindrical structure.…”