The Indirect Excitons Contribution to the Polarizability of a Dielectric Nanoparticle

Semiconductors - The optical properties of dielectric nanostructures strongly depend on dielectric nanoparticles (NP) polarizability which can take the high values even interacting with...     

On an exciton with a spatially separated electron and hole in quasi-zero-dimensional semiconductor nanosystems

The theory of an exciton with a spatially separated electron and hole (the hole is in the quantum dot volume, and the electron is localized at the outer spherical quantum dot-dielectric matrix interface) is developed within the modified effective mass method. The effect of significantly increasing the exciton-binding energy in quantum dots of zinc selenide, synthesized in a borosilicate glass matrix, relative to that in a zinc-selenide single crystal is revealed.     

Biexcitons formed from spatially separated electrons and holes in quasi-zero-dimensional semiconductor nanosystems

A theory of biexcitons (formed from spatially separated electron and holes) in nanosystems that consist of zinc-selenide quantum dots synthesized in borosilicate glassy matrices is developed. The dependences of the total energy and the binding energy of the singlet ground biexciton state in such a system on the spacing between the quantum-dot surfaces and the quantum-dot radius are derived by the variational method. It is shown that biexciton formation is of the threshold character and possible in nanosystems, in which the spacing between the quantum-dot surfaces is larger than a certain critical spacing.     

Binding energy of the exciton of a spatially separated electron and hole in quasi-zero-dimensional semiconductor nanosystems

A quasi-zero-dimensional semiconductor nanosystem involving a hole moving in the volume of a semiconductor quantum dot (QD) and an electron localized on the outer spherical interface between the QD and a dielectric matrix has been studied. It is established that the ground-state binding energy of the exciton formed by these spatially separated electron and hole is significantly increased compared to the exciton binding energy in single crystals of cadmium sulfide and zinc selenide.     

Exciton states in semiconductor spherical nanostructures

The results of theoretical studies of the energy spectra of excitons moving in semiconductor spherical quantum dots are described. The contributions of the kinetic electron and hole energies, the energy of the Coulomb interaction between an electron and hole, and the energy of the polarization interaction between them to the energy spectrum of an exciton in a quantum dot with a spherical (quantum dot)-(insulator medium) interface is analyzed.     

Exciton states in quasi-zero-dimensional semiconductor nanosystems

The variational method in the context of the modified effective mass approximation is used to calculate the dependence of exciton ground-state energy for a quantum dot embedded in a borosilicate glassy matrix on the quantum dot radius. It is shown that the peaks in the absorption and low-temperature luminescence spectra of such a nanosystem are shifted to shorter wavelengths due to size quantization of the exciton ground-state energy in the quantum dot.     

Interband absorption of light in semiconductor nanostructures

Interband absorption of light in a small semiconductor microcrystal was investigated theoretically within the dipole approximation. An expression for the light-absorption coefficient was derived for the situation where the polarization-related interaction of an electron and hole with the microcrystal surface is dominant. It is shown that the edge of absorption in a microcrystal shifts to shorter wavelengths if the polarization-related interaction of electrons and holes with the microcrystal surface is taken into account. It is ascertained that the absorption edge for small microcrystals is formed by two transitions comparable in intensity; these transitions occur from different levels of size-related quantization for a hole to the lower level of size-related quantization for an electron.