Characteristics of the low electron density surface layer on BaTiO3 thin films

The surfaces of epitaxial BaTiO3 films on SrTiO3 substrates were investigated by x-ray reflectivity (XRR) and angle-resolved x-ray photoelectron spectroscopy (ARXPS). It was shown by XRR analysis that there exists a low electron density surface layer (about 87%-93% of the electron density of the underneath BaTiO3 layer) of 15 A on top of the film. Moreover, ARXPS results revealed a surface core-level shift of Ba in layer of about 11 A, a value which is in agreement with the thickness obtained by XRR, indicating that the surface core-level shift of Ba stems from the low electron density surface layer. (c) 2008 American Institute of Physics.