Substrate temperature dependence of phase and orientation of pulsed laser deposited Bi-La-Ti-O thin films

Bi3.25La0.75Ti3O12 (BLT) thin films were grown by pulsed laser deposition at substrate temperatures ranging from 400 to 800degreesC. The phase, orientation, and surface morphology of the deposited films were investigated in order to understand the deposition behavior of the BLT films. As the substrate temperature was increased to 800degreesC, the films showed a tendency to grow with c-axis preferred orientation and a rough surface. At lower substrate temperatures, however, polycrystalline BLT films were formed. In addition, at the lowest substrate temperature of 400degreesC, the film consisted mostly of a nonferroelectric fluorite-like phase. This was attributed to the difficulty in forming a perfectly layered structure. The fluorite-like phase was transformed to a ferroelectric polycrystalline BLT phase through annealing in flowing oxygen at 600degreesC.