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Journal of Physical Studies 5(1), 80–84 (2001)
DOI: https://doi.org/10.30970/jps.05.80 OPTICAL AND SPECTRAL CHARACTERISTICS OF THE BULK AND Tl+-DOPED К2ZnI4 SINGLE CRYSTALSM. S. Pidzyrailo, V. V. Vistovsky, H. K. Maksimovich, I. V. Stefanskiy
Ivan Franko National University of Lviv, Chair of Experimental Physics, |
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Optical reflection spectra in the polarized light of the К$_{2}$ZnI$_{4}$ crystal were studied at 77 К. A spectral position of the exciton reflection peaks $n=1$ (4.90 eV) and $n=2$ (5.20 eV) was determined. Band gap width $E^{\perp}_{g}=5.30$ eV, exciton binding energy $F=0.40$ eV and its radius $r_1=4.3$ \AA were caculated. Emission spectrum of Tl$^{+}$-centres in the К$_{2}$ZnI$_{4}$:Tl crystal ($C_{\rm Tl}= 0.0006$ mol.\%) consists of the $A_{х}$-band only peaking at 2.83 eV under 77 К. The existence of two components of the $A$ absorption band ($A_{1}$(4.39 еВ) and $A_{2}$(4.46 eV)), the $B$ absorption band (4.80 eV) and the emission band of double (Tl$^{+}$)$_{2}$-centers (3.19 eV) were found in a crystal with the concentration $C_{\rm Tl}=0.006$ mol.\%. A sharp decrease of the emission quantum yield of Tl$^{+}$-centers in the К$_{2}$ZnI$_{4}$:Tl crystal takes place already at $T\geq 100$ К.
PACS number(s): 78.55.Fv, 61.72.-y, 81.10.Fq