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Investigation of the Light Absorption Mechanisms near Exciton Resonance in Layered Crystals
Author(s) -
Zhirko Yu.I.
Publication year - 1999
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/(sici)1521-3951(199905)213:1<93::aid-pssb93>3.0.co;2-4
Subject(s) - exciton , polariton , oscillator strength , condensed matter physics , absorption (acoustics) , electron , resonance (particle physics) , exciton polaritons , materials science , molecular physics , chemistry , spectral line , atomic physics , physics , optics , quantum mechanics
Low temperature exciton absorption spectra of InSe crystals have been studied. A simple analytical dependence has been established when the integral absorption coefficient K exc of the n = 1 exciton band is a function of its half‐width. Such light absorption mechanisms as polariton mechanism, indirect phototransitions, “resonant exciton” and exciton states degenerated with 2D conduction electrons distributed in quantum wells have been considered. It has been shown that the phenomena connected with the spatial dispersion of light make the main contribution to K exc growth for InSe crystals in the vicinity of the exciton resonance at low temperatures. A comparison of the Pekar and Davydov models with the experiment permitted establishing the field of application for each of them. The oscillator strength of the exciton and band‐to‐band optical transitions f exc = f cv = 0.11, plasma frequency ω p = 2.05 × 10 14 s —1 and value of longitudal–transversal splitting Δ L‐T = 0.57 cm —1 of polariton branches have been found for InSe crystals.