LIGHT-INDUCED ABSORPTION AND PROPERTIES OF SHALLOW IMPURITY LEVELS INUNDOPED AND CE-DOPED BATIO3

Spectral and temporal characteristics of light-induced absorption for BaTiO3 crystals undoped and doped with various amounts of Ce were inve stigated and compared. Dark decay of light-induced absorption with two time constants corresponding to two shallow levels was observed in al l crystals investigated. Light-induced absorption spectra were then re solved into two components, slow and fast, according to the dark-decay time constants. The resolved spectra reveal that in all the undoped a nd Ce-doped crystals the two shallow levels have the same defect origi ns, independently of doping. The thermal activation energies of the tw o shallow levels were deduced to be similar to 0.7 and similar to 0.5 eV in all crystals, and the 0.7-eV shallow level is attributed to Fe4/5+. Some other important parameters for the two shallow levels were a lso determined. (C) 1998 Optical Society of America.