THICKNESS DEPENDENCE OF FERROELECTRIC DOMAINS IN THIN CRYSTALLINE FILMS

The thickness dependence of ferroelectric domains in thin free-standin g BaTiO3 crystalline films has been studied by transmission electron m icroscopy. It is found that the widths of ferroelectric domains decrea se as the film thickness decreases. This phenomenon may indicate that the ferroelectric properties of thin films are weakened due to surface relaxation effects, including lattice relaxation and a change of spon taneous polarization and charge compensation. The weakening of ferroel ectric domains is suggested as a transition state from ferroelectric t o paraelectric phase of the BaTiO3 thin film. The thickness of the sur face relaxation layer of totally nonferroelectric film is on the order of 10 nm. (C) 1994 American Institute of Physics.