Thin BaTiO3 films grown on SrTiO3 substrates were characterized by means of positron annihilation. The films were deposited by molecular-beam epitaxy without using O source. The Doppler broadening spectra of annihilation radiation and X-ray diffraction of the films were measured and it was found that vacancy-type defects such as O vacancies and other related defects caused lattice relaxation in the films. These defects disappeared after the films were annealed at 600C in an O2 atmosphere. Lattice relaxation in the films was also observed when the films were annealed at 1050C, but there was no direct relationship between the lattice relaxation that occurred at this temperature and vacancy-type defects. Vacancy-type defects were introduced into the SrTiO3 substrates by the growth of the BaTiO3 films. These defects were identified as being O vacancies or defects related to O vacancies, and they appeared as the result of diffusion of O towards the BaTiO3 films. Almost all of the O vacancies in the SrTiO3 substrates annealed out at 500C.

Vacancy-Type Defects in BaTiO3/SrTiO3 Structures Probed by Monoenergetic Positron Beams. A.Uedono, K.Shimoyama, M.Kiyohara, Z.Q.Chen, K.Yamabe, T.Ohdaira, R.Suzuki, T.Mikado: Journal of Applied Physics, 2002, 91[8], 5307-12