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)O-3] thin films, TiOx films of thickness similar to 20-480nm were prepared on coming-1737 glass substrates by r.f. magnetron sputtering and then post-annealed in air at different temperatures (350-650 degrees C). Depending mainly on seed layer thickness, TiOx films transform either into anatase or rutile TiO2 after air-annealing. Thin PZT films (similar to 150 nm)were then deposited on substrates pre-coated with TiOx seed layers and air-annealed at 650 degrees 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 (101) textured rutile TiO2 of thickness similar to 100 nm favours the growth of highly oriented perovskite phase along (100) 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 similar to 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 TiCx seed layer influence remarkably the crystalline phase, texture and surface morphology of the grown PZT films. (C) 2008 Elsevier B.V. All rights reserved.