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Investigation of the Light Absorption Mechanisms near Exciton Resonance in Layered Crystals
Author(s) -
Zhirko Yu.I.
Publication year - 2000
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 - 10.1002/1521-3951(200005)219:1<47::aid-pssb47>3.0.co;2-q
Subject(s) - exciton , oscillator strength , polariton , materials science , absorption (acoustics) , condensed matter physics , impurity , exciton polaritons , crystal (programming language) , doping , absorption band , scattering , absorption spectroscopy , molecular physics , chemistry , spectral line , optics , optoelectronics , physics , organic chemistry , astronomy , computer science , composite material , programming language
Wide temperature range (4.5 to 300 K) exciton absorption spectra of pure, doped and GaSe crystals intercalated by manganese have been studied. It has been shown that at low temperatures in p‐type GaSe crystals the degeneration in the momentum space of the n = 1 exciton band with holes localized in quantum wells leads to suppression of the exciton oscillator strength f exc . The slight doping (0.1 wt%) of GaSe by Mn impurities compensates holes and restores the polariton light absorption mechanism. The oscillator strength of the exciton and band‐to‐band optical transitions f exc = f cv = 0.05, plasma frequency ω p = 2.9 × 10 14 s —1 , and value of longitudinal‐transversal splitting Δ L‐T = 0.4 cm —1 of polariton branches have been found for GaSe crystals. It is assumed that a slight excess of f exc over f cv in intercalated GaSe crystals occurred due to the participation of the “indirect phototransition” mechanism in the light absorption when the excitons undergo an additional scattering on local interlayer optical vibrations.