Optical studies of 0.65PbMg 1/3Nb 2/3O 3–0.35PbTiO 3 thin films

Abstract

0.65PbMg 1/3Nb 2/3O 3–0.35PbTiO 3 (PMN–PT) thin films with different deposition temperatures were fabricated on (0 0 1)MgO single crystal substrates using pulsed laser deposition (PLD). X-ray diffraction (XRD) showed that the films are epitaxially grown on (0 0 1)MgO substrates. Spectroscopic ellipsometer (SE) was used to characterize the optical properties including refractive indices as well as extinction coefficients of these PMN–PT films in energy range of 0.75–3.5 eV. By fitting the measured ellipsometeric spectra, film thicknesses, surface roughness and optical properties were derived for all PMN–PT films. The film thickness and surface roughness obtained by SE were consistent with those measured by scanning electron microscopy (SEM) and atomic force microscopy (AFM) respectively. The optical band gap energies of PMN–PT films were deduced from the obtained extinction coefficients using Tauc equation. These values were comparable to those obtained by optical transmittance measurements. Our analysis revealed that the optimum refractive index emerges as the film fabricated at ∼670 °C.