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Journal of Physical Studies 4(3), 303–305 (2000)
DOI: https://doi.org/10.30970/jps.04.303 LUMINESCENT PROPERTIES OF CdBr2M. Rudka1, S. Charambura1, V. Antonyuk2, I. Matviishyn2, B. Kostyuk2
1State University ‟Lvivska Politechnika”, |
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Photo- and X-rays luminescent properties of the layered CdBr$_2$ crystals in the temperature region of 80...500 K have been investigated. It has been found out that the most effective luminescence is excited at the temperatures 100...140 K with the ultraviolet light from the exciton absorption region of crystals (259 nm). The annihilation of excitons autolocalized on the deep acceptors causes the luminescence in the region 380 nm which is quenched completely at the temperatures above 120 K. Strong exciton-phonon and electron-phonon interactions cause the excitons destruction and recombination of nonequilibrium electron-holes pairs through the donor-% acceptor (DA) complexes of intrinsic and impurity defects. Nonequilibrium charge carriers generated by the gap light recombine more effectivelly in the surface crystal region causing the yellow-% green luminescence with the maximum near 540...570 nm and also diffuse into the sample bulk and are captured on the traps causing the effective red thermoluminescence at $T>200$ K. The red photoluminescence with the maximum near 650 nm has been caused by irradiative recombination of electrons and holes generated by light long-wave absorption edge at 270...280 nm through DA defect complexes in the CdBr$_2$ crystals bulk. Moreover, in the surface area the nonequilibrium carriers have been captured and thermoluminescenting with green light with the maximum 510 nm at $T<200$ K. At the room temperature the relaxation time of electron-holes pairs created by radiation on the associated DA light centres has been decreased due to a strong influence of phonon processes which causes the fluorescence of the CdBr$_2$ crystals with the maximum near 510 nm.
PACS number(s): 71.10.+x, 34.80.Kw, 61.14.Dc