Indirect Excitons and Polarization of Dielectric Nanoparticles

Abstract

Indirect excitons (IX) are widely studied for the purpose of fundamental physics such as Bose−Einstein condensate formation and to develop new devices for photovoltaics, conversion, accumulation, and transport of energy and the creation of quantum-optical and exciton devices. The excitons in dielectric nanoparticles (NPs) determine the nanosystem physical properties, which strongly depend on NP polarizability. It can take the high values even when interacting with low-intensity radiation. In article, we show that the IX formation leads to high NP polarizability that is inversely proportional to exciton effective mass and directly proportional to the permittivity of the nanosystem. Also, it is found that size dependence of the IX energy spectrum weakly affects NP polarizability. For a quantitative assessment, we used a nanosystem containing a spherical dielectric alumina nanoparticle in a dielectric medium with a lower permittivity, and we found that NP polarizability can achieve many orders of magnitude higher values than for the atomic and molecular electron transition cases. From the results, it can be concluded that dielectric nanosystems can be used for obtaining highly polarized NP and the long-lived IX. It is important for excitonic physics, instrumentation, nanotechnology, and materials science where excitons and NP are in demand as among the main elements that determine the required properties.

Spatially Indirect Excitons’ Spectroscopy in Germanium Quantum Dots

“…They are bounded from above by the boundary of the spectrum max 1, () l Ea Mechanisms underlying the formation of the interband and intraband absorption (emission) spectra in a nanosystem are proposed. It is shown that spectra of interband absorption (emission) consist of energy bands that are formed by electron transitions between quasi-stationary and stationary states, and intraband absorption spectra consist of zones that appear due to electron transitions between stationary states [5][6][7][8][9][10].…”

Recent Advancement on the Excitonic and Biexcitonic Properties of Low-Dimensional Semiconductors

“…Owing to the fact that the class of 2D materials presents some distinctive features, which are highly dissimilar in comparison with those of their threedimensional (3D) correspondents, it is used for the next-generation ultra-thin electronics [88]. In this context some researchers explained the role of the expansion of indirect excitons (an indirect exciton-IX-is a bound pair of an electron and hole in separated QW layers [89]), which is observed in vdW transition metal dichalcogenide (TMD) heterostructures at room temperature, this study helping for the progress of excitonic devices with energy-productive computation and ideal connection quality for optical communication cases [90,91]. Various theoretical and experimental analyses have been developed for the improvement of the excitonic devices that use IXs propagation in different types of single QWs and coupled QWs [92,93].…”