PHOTOLUMINESCENCE AND PHOTOCONDUCTIVITY OF ZnS:Ti SINGLE CRYSTALS
The photoconductivity and photoluminescence of ZnS:Ti crystals in the visible spectra region are studied. The scheme of optical transitions within Ti2+ impurity centers is established. It is shown that the high-temperature photoconductivity of ZnS:Ti crystals is controlled by optical transitions of electrons from the 3А2(F) ground state to the higher levels of excited states of Ti2+ ions, with subsequent thermal activation of the electrons to the conduction band. Efcient excitation of intracenter luminescence of ZnS:Ti crystals is attained with light corresponding to the region of intrinsic absorption in Ti2+ ions