Electrical properties and crystal structure of (Ba,Sr)TiO3 films prepared at low temperatures on a LaNiO3 electrode by radio-frequency magnetron sputtering

(Ba,Sr)TiO3 films on a LaNiO3 underlayer were prepared by radio-frequency magnetron sputter deposition. The onset of crystallization of the films occurred at a deposition temperature (T-d) as low as 200 degrees C. Good crystallinity was observed at T-d greater than or equal to 350 degrees C. A moderate high dielectric constant (epsilon(r) similar to 170-250) of the films was obtained at relatively low T-d similar to 200-360 degrees C. The value of epsilon(r) showed a much slower increase with T-d greater than or equal to 350 degrees C than that expected from the progress of crystallinity. The deviation was attributed to an interdiffusion layer formed between the him and underlayer, which also caused an abnormal contact potential barrier and a decline of the epsilon(r) value of the samples postannealed at 350 degrees C. Annealing at 300 degrees C under O-2 atmosphere lessened the oxygen deficiency in the film and enhanced the dielectric constant without forming an interfacial layer. (C) 1997 American Institute of Physics.