X-ray photoelectron spectroscopy study on the composition and structure of BaTiO thin films deposited on silicon

X-ray photoelectron spectroscopy XPS.spectral analysis showed that Ba ions in BaTiO3 thin films prepared by the sol–gel technique consist of one phase corresponding to one electronic state, which we call the b-phase. This phase became stronger at the same depth with increasing annealing temperature. With our preparation conditions, we can prepare BaTiO3 thin films with Ba electronic states as in bulk BaTiO3. During Arq sputtering, a mixture of the different oxidation states Tiq2, Tiq3, Tiq4 of titanium are present as established by XPS. The concentration of Tiq3 increases with increasing annealing temperature. For thin films annealed at 6758C the atomic concentration of Tiq3 is of the order of that of Tiq4. The binding energy of the oxygen O 1s main peak increases with increasing number of sputter cycles. Oxygen atoms terminating the oxide surface are bound differently from subsurface oxygen atoms. Outer-layer oxygen atoms are less negatively charged than in the normal oxide state. X-ray diffraction patterns and XPS analysis of the annealed films show that films annealed at 6008C for 2 h have high crystallinity, the desired stoichiometry, and less Tiq3 defects. q2000 Elsevier Science B.V. All rights reserved