Texture control of PbTiO3 and Pb(Zr,Ti)O3 thin films with TiO2 seeding

Abstract

The nature and the role of 1 to 5 nm thick TiO2 seed layers for the growth of textured PbTiO3 and Pb(Zr,Ti)O3 thin films on textured Pt(111) thin film substrates have been studied. Under otherwise identical in situ sputter deposition process conditions, the PbTiO3 texture could be turned from (100) to (111) orientation by adding the seed layer. This is demonstrated by patterning the TiO2 film. Auger electron spectroscopy and x-ray photoemission spectroscopy showed that the seed layer was a continuous TiO2 film. X-ray photoelectron diffraction measurements revealed epitaxial ordering in the seed layer. As there is no azimutal order among the Pt grains, the reduced information of azimutally averaged polar cuts is obtained. These give strong evidence for a strained rutile (110) structure. Various deposition experiments indicated that the TiO2 is effective only when it is ordered before the PbTiO3 nucleation starts. The epitaxial relationship between PbTiO3(111) and Pt(111) is thus mediated by the intermediate, epitaxial TiO2 film, which is dissolved or transformed to PbTiO3 afterwards. The observed growth behavior is discussed in terms of surface and interface energies.