Spectroscopic ellipsometry study of epitaxially grown Pb(Mg₁/₃Nb₂/₃)O₃–PbTiO₃/MgO/TiN/Si heterostructures

Abstract

0.65Pb(Mg₁/₃Nb₂/₃)O₃–0.35PbTiO₃(PMN–PT) thin films have been grown on MgO/TiN-buffered Si(001) substrates using pulsed laser deposition. Their structural properties and surface morphology were examined by x-ray diffraction and scanning electron microscopy, respectively. All PMN–PT films grown at 670 °C show a cube-on-cube epitaxial relationship of PMN–PT(100)∥MgO(100)∥TiN(100)∥Si(100). Discernable interfaces between layers in the heterostructures and crack-free surfaces are evident. A spectroscopic ellipsometer was used to study the optical characteristics of the films. It was revealed that the refractive index of the PMN–PT is ∼2.50 as measured at 635 nm. This value is only slightly less than that of the PMN–PT single crystal of 2.60. Our results suggest that the PMN–PT/MgO/TiN/Si heterostructure has an excellent potential for use in integrated optical waveguide devices.