ESR investigation of ferroelectric films

Abstract

The investigation of SrTiO₃: Ca, Cr, PbZr_0.58Ti_0.42O₃ and PbTiO₃ ferroelectric films on the substrate of Al₂O₃ and MgO single crystals respectively was performed by ESR method. Study of the SrTiO₃ films with the thickness h = 17000Ä and 3500 Ä doped by 0.1% Cr and 0.2% Ca was carried out at T = 18 K with and without illumination of ultraviolet light (λ= 365 nm). Analysis of the observed spectra had shown that there were two Cr³⁺ ESR lines with g-factors 1.977 and 1.974 in the thick film whereas in thin film there was line with g = 1.974 with higher intensity than that in thick film. Calculations lead to the conclusion that the line with smaller g-factor belongs to Cr³⁺ centers nearby films surface. Small intensity line with g = 2.002 revealed in the films most probably belongs to O⁻ center. Its intensity increases after illumination, but it conserves even without illumination contrary to the bulk samples. ESR spectra of PZT and PT films were recorded at T = 77 K and 300 K for different orientations of magnetic field. Analysis have shown that the spectra origin is Cr, Mn, V and Fe impurity ions. The influence of the revealed defects and impurities on the properties of the films is discussed.

Key Words:

• thin film
• thick film
• surface center
• ESR method