Effects of single-coated layer thickness on the microstructure, leakage current and dielectric tunability of Na0.5Bi0.5(Ti,Zn)O3-δ thin films prepared by metal organic decomposition

• All films exhibit perovskite structures with different relative intensities of (110) peaks.
• A typical columnar structure can be found in the film of 20 nm/l.
• Larger tunability and figure of merit are observed in the film of 20 nm/l.
• The tunability is increased with the increase of electric field or decrease of frequency.

Na0.5Bi0.5(Ti,Zn)O3-δ (NBTZn) thin films with various single-coated layer thicknesses (35, 25, 20 and 15 nm) annealed at 550 °C were fabricated on indium tin oxide/glass substrates using a metal organic decomposition process. The effects of single-coated layer thickness on the crystal structure, morphology, leakage current as well as dielectric tunability are investigated. All the films exhibit polycrystalline perovskite structures with different relative intensities of (110) peaks. The highly preferred orientation in the film of 20 nm per layer (nm/l) is consistent with the typical columnar structure observed from cross-sectional morphology. Also, for the film with 20 nm/l, it exhibits the higher tunability of 43.2% and figure of merit of 8.1 at 240 kV/cm and 100 kHz due to well-crystallization and lower content of defects. Meanwhile, the effects of electric field on the tunability for all the NBTZn films and frequency on the dielectric constant-electric field loops for the film of 20 nm/l are discussed.

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