Target-quality dependent crystallinity of sputter-deposited LiNbO3 films: Observation of impurity segregation

The crystallinity of LiNbO3 (LN) films sputtered from LN single crystal target was shown to be better than those from sintered target, confirming that the target quality is an important factor. In the particular case, Li2CO3 precipitated and crystallized to form a c-axis oriented overlayer on the surface of amorphous LiNbO3 film below 400 °C at an early stage of using an as-sintered target. This phenomenon reflects highly mobile nature of Li ions, resulting in phase-separation in the Li2O–Nb2O5 system under the plasma irradiation, which behavior represents Li-based electrolyte.