Influence of PbTiO3 buffer layers on microstructural properties of Pb(Zr,Ti)O-3 films deposited by sputtering

Pb(Zr,Ti)O-3 (PZT) films with very thin PbTiO3 (PT) buffer lavers inserted between the film and the Si/SiO2/Ti/Pt substrate were grown by a rf magnetron sputtering technique. The X-ray diffraction patterns and the surface morphology of PT as a function of the thickness, in the range of 20 to 400 Angstrom, were first investigated. Such a marked contrast in morphological features was not observed when the thickness was above 400 Angstrom. The films were grown in-situ at 500 degrees C. We found modification of the PT orientation when its thickness varied between 20 Angstrom and 400 Angstrom. This implies a gradual evolution of the lattice parameters in the nucleation stage of PT films. Insertion of these buffer layers was found to exert marked effects. Up to 400 Angstrom the PT was grown with a [100] preferred orientation. The orientation of PZT could be controlled by changing the thickness and then the orientation of PT. The results will be discussed in terms of the effects of the buffer layer on the crystalline structure and the surface morphology of PZT.