Dependence of crystalline structure and lattice parameters on film thickness in PbTiO3/Pt/MgO epitaxial structure

In PbTiO3 (2.2-398nm in thickness)/Pt/MgO(100) structure, the dependence of the crystalline structure and lattice parameters of PbTiO3 thin films on the film thickness was investigated using the theta-2 theta XRD method and the energy dispersive typed total reflection X-ray diffraction method (ED-TXRD). By using the ED-TXRD method, we can easily evaluate the in-plane structure of island-structured PbTiO3 films at the initial growth stage. Although the PbTiO3 thin films were highly c-axis orientated, the formation of some a-domains was observed with increasing thickness. The lattice parameters of the vertical dimension were dependent on the film thickness, unlike those in-plane. From these experimental results, the inner strain occurring in PbTiO3 thin films is discussed.