Effect of magnetic and electric fields on optical properties of semiconductor spherical layer

Theoretical investigation of the influence of magnetic and electric fields on the energy spectrum and wave functions of electron in semiconductor spherical layer has been performed. The case of co-directed electric and magnetic fields has been considered. The Schrödinger equation has been solved using the method of expansion for the wave function of electron in the spherical layer under external fields by applying the complete set of wave functions of a quasi-particle in a spherical nanostructure without the external fields. It has been shown that electric and magnetic fields take off the spectrum degeneration with respect to the magnetic quantum number. The external fields rebuild the energy spectrum and deform wave functions of electron. Moreover, their influence on the spherically symmetric state is the largest one. Increasing the magnetic field induction entails a monotonous dependence of the electron energy for the states with m > 0 and non-monotonous one for the states with m < 0. The ground state of electron is successively formed by the states with m = 0, –1, –2, … with increasing the induction of magnetic field. The enhancement of the electric field mainly diminishes the electron energy. The influence of field on the energy and intensities of the 1p-1s intraband transition has been studied. It has been shown that there exists a certain value of the electric field, at which the energy of quantum transition doesn’t depend on the magnetic field induction

Electron spectrum in confined cylindrical nanoheterosystem with finite depth of potential well

Electron spectrum in cylindrical quantum dot HgS embedded into ZnS medium is calculated using the variational method with variational parameter in Hamiltonian. The dependence of energy spectrum on the quantum well sizes is established. The electron spectrum calculated in the framework of infinitely deep potential well is compared to the one obtained within the variational method. It is shown that the first method gives satisfactory results for the ground level only and at rather big sizes of quantum well.На основі варіаційного методу з варіаційним переметром у гамільтоніані розраховано електронний спектр у циліндричній квантовій точці HgS, розміщеній у середовищі ZnS. Встановлена залежність енергетичного спектру, розрахованого в рамках моделі безмежно глибокої потенціальної ями, задовільно працює лише для основного рівня і при досить великих розмірах квантової ями

Hydrogenic impurity states in CdSe/ZnS and ZnS/CdSe core-shell nanodots with dielectric mismatch

Within the effective mass approximation we theoretically studied the electronic properties of CdSe/ZnS and ZnS/CdSe core-shell quantum dots surrounded by wide-gap dielectric materials. The finite element method is used to obtain the lowest impurity levels and the carrier spatial distribution within the dot. We found that in these zero-dimensional semiconductor structures the electron energy is sensitively dependent on the dielectric constants of the embedding and on the heterostructure geometry. The influence of polarization charges on the binding energy of hydrogenic impurities off-center located is also investigated. The results suggest that in dielectrically modulated nanodots the donor energy can be tuned to a large extent by the structure design, the impurity position and a proper choice of the dielectric media