Effects of stress on the optical properties of epitaxial Nd-doped Sr₀.₅Ba₀.₅Nb₂O₆ films

Abstract

Nd-doped Sr₀.₅Ba₀.₅Nb₂O₆ (SBN) thin films with thicknesses ranging from 15 nm to 460 nm were grown on MgO (100) substrates using pulsed laser deposition technique. X-ray diffraction studies showed that the films were highly (001)-oriented and epitaxially grown on the substrates. Raman spectroscopy revealed the presence of residual stresses in the films especially for those with thicknesses below 100 nm. Transmittance and photoluminescence spectra revealed that the band-gap energies as well as the light-induced emission bands were shifted to higher energies as the film thickness decreased. The Nd³⁺ emission lines in the films were also dependent on film thickness. Origins of these observations were discussed based upon the stress as well as grain size effects.