Characteristics of Ba0.5Sr0.5TiO3 thin films grown by ultraviolet-assistedpulsed laser deposition

The microstructure and properties of barium strontium titanate (BST) thin f ilms grown by an in situ ultraviolet-assisted (UV-assisted) pulsed laser de position (UVPLD) technique are reported in this paper. In comparison with B ST films grown by conventional pulsed laser deposition (PLD) under similar conditions, but without UV illumination, the UVPLD-grown films exhibited im proved structural, electrical, and optical properties. X-ray photoelectron spectroscopy showed that when exposed to atmosphere, Ba atoms from the oute rmost layers formed a thin layer of barium carbonate, which negatively affe cts the film electrical characteristics. UVPLD-grown films exhibited a smal ler amount of Ba atoms within the carbonate layer, resulting in better elec trical characteristics. The dielectric constant of 40-nm-thick films deposi ted at 650 degrees C by UVPLD and PLD were determined to be 281 and 172, re spectively. The leakage current density of the UVPLD-grown films was in the mid-10(-8) A/cm(2) range, a factor of 2 lower than that obtained from PLD- grown films.