We investigate the microstructural evolution and epitaxial alignment of thin films of LiNbO3 deposited by the Metallo-organic decomposition method on Al2O3. The LiNbO3 films are prepared by spin coating and thermal decomposition of a solution of Metallo-organic precursors on single-crystal, <0001> oriented, Al2O3 substrates, followed by heat treatment in a quartz tube furnace at temperatures ranging from 500 to 1000 °C.

X-ray diffraction analysis reveals that films heat treated at 600 °C for 1 h are highly oriented along the c-axis direction, but the alignment is not good enough to permit channeling of 2 MeV He++ particles. Heat treatment at 900 °C improves significantly the epitaxial alignment as determined by ion-channeling measurements. However, concomitantly with the improvement in crystal orientation, the films break up into a network of LiNbO3 grains, partially uncovering the Al2O3 substrates along grain boundaries. Pole figure analysis shows that all the grains share the same in-plane orientation.