Luminescent Properties of Activated CdI2Crystals

Data are presented on the luminescent properties of melt-grown CdI₂crystals activated with anion (I, S) and cation (Cd, Tl, Sb, Pb, Sn, Mn) impurities. The measured spectral and temporal responses of roentgeno- and thermoluminescence, in conjunction with earlier kinetic, optical, and photoelectric data for nominally pure and activated CdI₂crystals, indicate that, under x-ray excitation at temperatures between 85 and 295 K, intracenter transitions of impurity ions occur only in CdI₂:Mn crystals. The low-temperature roentgenoluminescence spectra of CdI₂activated with Cd, Pb, Sn, and Sb show, along with the anion-exciton emission at 530–575 nm, a band at 640–700 nm related to associates of native defects and impurities. In the 85-K electroluminescence spectra of CdI₂:Cd and CdI₂:Pb, the relative intensity of the shorter wavelength emission increases with increasing electric field, which is probably due to recombination at V _khole centers with different depths. The trapping levels in the crystals studied are mainly due to intrinsic defects and have a low retrapping efficiency. The radiative recombination and trapping processes are shown to occur at different centers.