Improved Optical, Dielectric, and Nonlinear Properties of Cacu3ti4o12 Films by Chromium Doping
20 Pages Posted: 6 Jul 2022
The optical and dielectric properties, microstructures, and nonlinear electrical performances were systematically investigated for Ca1-xCrxCu3Ti4O12 (x = 0.00–0.40) thin films prepared on Pt/Ti/SiO2/Si substrates using the sol-gel method. X-ray photoelectron spectroscopy verified that Cr3+ and Cr6+ were present in the thin films. Additionally, the content of the titanium oxide (TiO2) secondary phase increased, the grain size decreased, and the surface roughness improved with an increase in the Cr doping content. The optical energy band gap (Eg) increased from 2.92 to 3.54 eV as a result of the reduced grain size and oxygen vacancy concentration while changes in the dielectric constants of the thin films followed the internal barrier layer capacitor model. Doping was found to decrease the dielectric loss and enhance the nonlinear properties, owing to the presence of the TiO2 secondary phase, high density, reduced grain size, incremental potential barrier height (Φb) and grain boundary resistance. The Ca0.8Cr0.2Cu3Ti4O12 thin film had a high dielectric constant of ~9340, low dielectric loss of ~0.012 at 1 kHz, nonlinear coefficient of ~4.64, and breakdown field of ~89 kV/mm. These results indicate that the doping of an appropriate of Cr can effectively modify the microstructure of CaCu3Ti4O12 thin films and improve their optical and electrical properties.
Keywords: CaCu3Ti4O12 thin film, Dielectric loss, UV-visible absorption, Nonlinear performances
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