Microstructure and surface morphology evolution of pulsed laser deposited piezoelectric BaTiO₃ films

In this paper, we analyze and elucidate the microstructure and surface morphology evolution of the piezoelectric BaTiO₃ films grown by pulsed laser deposition on platinized silicon substrates. The films exhibited a columnar structure where the surface morphology evolved from a pyramid to star-like to hexagram shape with (111)-preferred orientation and increasing film thickness. In each column, a twin lamellae structure was formed that was found to enhance the lateral growth and coalescence of the grains. The high stability along the reentrant angle of the twin lamellae controlled the competition between the columnar growth and their coarsening. We present a growth model for BaTiO₃ films and demonstrate the correlation of the growth mode and lamella twins during morphological evolution.