Defects and impurities in SrTiO3 films: Evidence from ESR

The investigation of the films with the thickness h=1700nm and 350nm doped by 0.1%Cr and 0.2%Ca on Al2O3 single crystal substrate was performed by ESR method. The spectra were recorded at T=18K with and without illumination o f ultraviolet light (lambda=365nm). Analysis of the observed spectra had sh own that there were two Cr3+ ESR lines with g-factors 1.977 and 1.974 in th e thick film whereas in thin film there was line with g=1.974 with higher i ntensity than that in thick film. Calculations lead to the conclusion that the line with smaller g-factor belongs to Cr(3+)centers nearby films surfac e. Small intensity broad line with g=2,011-2.021 which was revealed under l ight illumination in the films most probably belongs to O- center. The infl uence of the revealed defects and impurities on the properties of the films is discussed.