Accommodation of excess Ti in a (Ba, Sr)TiO3 thin film with 53.4% Ti grownon Pt/SiO2/Si by metalorganic chemical-vapor deposition

The microstructure and chemistry of a Ti-rich (Ba, Sr)TiO3 film with 53.4% Ti deposited on a Pt/SiO2/Si substrate by metallorganic chemical-vapor depo sition was studied using high-resolution transmission electron microscopy a nd elemental mapping in electron energy-loss spectroscopy. We established t hat the Ti/Ba ratio at all the grain boundaries in this film is significant ly higher than that in the grain interiors. Structural images revealed the presence of disordered amorphous-like regions at some of the grain boundari es and triple junctions; these regions were tentatively identified as those having the highest Ti/Ba ratio in the chemical maps. Analysis of the elect ron energy-loss near-edge structure for the O-K edge indicated an increased titanium-to-oxygen coordination at the grain boundaries. No second phase w as detected at the (Ba, Sr)TiO3/Pt interface. (C) 1999 American Institute o f Physics. [S0003-6951(99)01735-0].