Preparation of lithium niobate thin films on diamond-coated silicon substrate for surface acoustic devices

摘要

Lithium niobate (LiNbO_3) has a piezoelectric property,with makes it an ideal material for the fabrication of surface acoustic wave (SAW) devices.When highly oriented LiNbO_3 films are deposited on a diamond substrate,a LiNbO_3/diamond-layered structure is produced that can be used for wide-bandwidth applications in SAW devices at high frequencies.The LiNbO_3 thin films were deposited on diamond-coated silicon substrates by the radio-frequency reactive sputtering system.When a stoichiometric LiNbO_3 target was used as the sputtering target and the cooling efficiency of the target was poor,only LiNb_3O_8 reflections appeared in X-ray diffraction patterns.It is suggested that the appearance of the Li-deficient phase of LiNb_3O_8 is caused by the dissociation of lithium and oxygen from LiNbO_3 during deposition.When an Li-enriched LiNbO_3 target was used as the sputtering target and the cooling efficiency of the target was good,stoichiometric LiNbO_3 films were prepared and the preferential orientation was (110).It was found that the use of the Li-enriched target and the cooling of the target suppressed the dissociation of lithium.