Restoration of Perovskite Phase in the Top Layer of Thin BTO Film by Plasma Treatment and Annealing.

We report a simple method to restore the perovskite phase in the top surface/sub-surface region of a thin film (similar to 100 nm) of barium titanate (BTO) fabricated by pulsed laser deposition on a platinized silicon surface and thus enhance its dielectric and ferroelectric properties. Phase evolution, surface morphology with local chemical composition of as-grown BTO films have been studied as a function of laser fluence. Investigations using x-ray diffraction, grazing-angle incidence x-ray diffraction and depth resolved x-ray photoelectron spectroscopy show that even after achieving a good phase formation there can be a presence of non-perovskite TiO2 phase at the surface and subsurface in such films that degrades its dielectric and ferroelectric response. The restoration of the degraded top layer was done by a combination of low energy Ar plasma treatment followed by an annealing process that enhances Ba content.