Pulsed laser deposition of epitaxial buffer layers on LiNbO3

The aim of this work is to obtain films with suitable characteristics for use as buffer layers for YBCO superconducting electrodes in LiNbO3-based electro-optic devices. For this purpose, an epitaxial buffer with single orientation and low surface roughness is required. The possibilities of two oxides, yttria-stabilised zirconia (YSZ) and CeO2, have been explored. The films were grown on X-cut LiNbO3 single crystals by pulsed laser deposition, and the influence of the processing conditions was studied. The YSZ films are epitaxial with single (0 0 1) orientation and the surface is appropriate for use as a first layer in a heterostructure. These were the properties found in films grown under relatively broad ranges of deposition parameters, which allows a very high reproducibility. However, the lithium-deficient LiNb3O8 compound was found at the interface in all the films. This compound was not observed when CeO2 films were deposited. These films are epitaxial and (0 1 1)-oriented, although they can also contain (0 0 1)-oriented crystals.