Optical properties of PLD-deposited barium strontium titanate (BaxSr1−xTiO3) thin films

Optical properties of PLD-deposited barium strontium titanate thin-films consisting of three stoichiometries have been investigated. Dielectric layers containing Ba
_x
Sr
_1-x
TiO
₃
(x = 30, 40, 50) have been deposited on glass substrates using pulsed laser deposition techniques using oxygen partial pressures of 1.3 Pa ± 0.13 Pa at 500 °C. The optical property investigation includes direct measurement of reflectance and transmittance using spectrophotometric methods to subsequently determine the refractive index (n), extinction coefficient (k), optical conductivity (σ), absorption coefficient (α) and optical band gap (E
_g
) using swept spectra in the ultraviolet, visible and near-infrared range (200-1100 nm). In this work these parameters are reported for Ba
_0.4
Sr
_0.6
TiO
₃
. Small differences in the transmittance were observed near the visible band edges when comparing each stoichiometry; sharp cutoffs were observed at the bands edges with a strong absorbance in the 200-300 nm band.