Optical properties of SrTiO3 thin films by pulsed laser deposition

SrTiO3 thin films were prepared on a fused-quartz substrate by pulsed laser deposition (PLD). Dense and homogeneous films with a thickness of 260 nm were prepared. Optical constants (refractive index n and extinction coefficient k) were determined from the transmittance spectra using the envelope method. The optical band gap energy of the films was found to be 3.58 eV, higher than the 3.22 eV for bulk SrTiO3, attributable to the film stress exerted by the substrate. The dispersion relation of the refractive index vs. wavelength follows the single electronic oscillator model. The refractive index and the packing density for the PLD-prepared SrTiO3 thin films are higher than those for the SrTiO3 films prepared by physical vapor deposition, sol-gel and RF sputtering. (orig.)