Influence of chemical composition, phase and thickness of TiOx (x ≤ 2) seed layer on the growth and orientation of the perovskite phase in sputtered PZT thin films

To study the influence of TiOx (x ≤ 2) seed layer on the formation of perovskite phase in lead zirconate titanate [Pb(Zr0.52Ti0.48)O3] thin films, TiOx films of thickness ∼20-480 nm were prepared on corning-1737 glass substrates by r.f. magnetron sputtering and then post-annealed in air at different temperatures (350-650 °C). Depending mainly on seed layer thickness, TiOx films transform either into anatase or rutile TiO2 after air-annealing. Thin PZT films (∼150 nm) were then deposited on substrates pre-coated with TiOx seed layers and air-annealed at 650 °C. It is found that thin TiO2 seed layers (≤150 nm) promote perovskite phase formation in PZT films. Anatase TiO2 promotes the growth of randomly oriented perovskite PZT. A (1 0 1) textured rutile TiO2 of thickness ∼100 nm favours the growth of highly oriented perovskite phase along (1 0 0) and surface morphology of these PZT films shows dense rosette structures. A TiO or an amorphous TiOx seed film does not initiate perovskite growth. As the thickness of the TiOx seed layer exceeds ∼150 nm, perovskite phase does not form readily irrespective of the crystalline form/phase of TiOx. Thus, chemical composition, crystalline phase and thickness of the TiOx seed layer influence remarkably the crystalline phase, texture and surface morphology of the grown PZT films.