Crystallization and optical properties of CCTO thin films under pressure influence

T. Sequinel, S.M. Tebcherani, J.A. Varela, E.T. Kubaski, L.H. Oliveira, M.S. Li
Universidade Estadual Paulista, BR

Keywords: CCTO, thin films, high pressure

Summary:

The goals of this work were to decrease the synthesis temperature of CCTO thin films using the pressure method, and to improve the homogeneity and density of the CCTO films in order to obtain better electrical and optical properties. CCTO thin films were deposited on Si/TiO2/SiO2/Pt substrate at 615 K with 2 MPa of pressure in air and compared to chemical deposition using spin coating with treatment at 975 K. Films deposited by high pressure method resulted in samples with higher density and more homogeneous in comparison to those obtained using chemical deposition. Furthermore, the pressure leads to cluster defects in the titanate increasing the photoluminescence intensity and shifting the main peak to 485 nm. Non-crystalline CCTO thin films deposited by spin coating and treated at 675 K were crystalized using high pressure treatment at 615 K. This low temperature of crystallization was observed in the photoluminescence spectrum, in which the two peaks (386 nm and 532 nm) in the chemical deposition films are characteristic of organic matter and, after 2 MPa treatment the organic signal was combined into the CCTO single peak (447 nm). The reduction of the crystallization temperature allows the use of less expansive substrates.