Pulsed laser deposition of c-oriented LiNbO3/LiTaO3 optical waveguiding bilayered films on silicon wafers

LiNbO3(LN)/LiTaO3(LT) bilayered films were grown on a p-type Si(lll) wafer coated with a SiO2 buffer by a pulsed laser deposition (PLD) technique. The XPS measurement showed that the stoichiometries of the LN and LT films were in good agreement with the target materials. The crystallinity of the as-grown films was analysed by XRD, which indicated that LN and LT were highly c-oriented while the SiO2 buffer was amorphous. The surface of the as-grown films was mirror-like, dense and crack-free; no large droplets were observed by scanning electron microscope (SEM). The thicknesses of the LN, LT and SiO2 films were about 960, 360 and 1800 nm, respectively. The interface between the LN and LT films was sharp. The X-ray energy dispersive spectrometer (XREDS) analysis to the different areas of the LN film showed that there was no variation of composition with depth. The optical waveguiding properties of the films were demonstrated by a prism coupler method.