An Investigation of PLD-Deposited Barium Strontium Titanate (BaxSr1-xTiO3) Thin Film Optical Properties

Reflectance and transmittance parameters of pulsed laser deposited barium strontium titanate (BST) were investigated using spectrophotometric methods. Three stoichiometries consisting of BaxSr1−xTiO3 (x = 0.30, 0.40, 0.50) were deposited on glass substrates using oxygen partial pressures of 1.3 Pa ± 0.13 Pa at 500 ̊C. Subsequently, the measured optical parameters were employed to determine the refractive index (n), extinction coefficient (k), optical conductivity (σ), absorption coefficient (α) and optical bandgap (Eg) using swept spectra in the ultraviolet, visible and near-infrared range (200 nm 1100 nm) as these have not been reported in the literature. The calculated parameters for Ba0.4Sr0.6TiO3 are reported in this experimental work. Minimal differences in the transmittance have been observed at the visible band edges when comparing each stoichiometry. Sharp cutoffs were observed at the bands edges and strong absorbance in the 200 nm 300 nm band as attributed to the crystal structure based upon the oxygen partial pressure during the deposition process.