Interface structure of Pb(Zr,Ti)O₃/MgO(001) epitaxial thin film in early stage of Stranski-Krastanov growth mode

This study investigated structural changes of Pb(Zr,Ti)O₃/MgO(001) thin films prepared using MOCVD in the early stage of the Stranski-Krastanov growth mode. The strain state of the interface layer and the island region of PZT changes accompanied by a downward climb motion of misfit dislocations into the PZT/MgO interface with crystal growth. The local strain field around the misfit dislocation core formed in-plane compressive strain in the in-plane direction in the interface layer, which was strained tetragonally, but the island region had a pseudocubic structure. These results suggest that the residual strain induced phase stability modulation as well as Zr/Ti compositional gradient. A proposed model structure involves consequently dislocations with 110_MgO slip on MgO can account for a stable interface without stacking fault. These results indicate the misfit strain-induced modulation of the interface structure and the phase stability in the early stage of the crystal growth on an atomic scale.