Fabrication of free standing LiNbO3 single crystal micro-platelets and their integration to Si-on-insulator platforms

Free standing single crystal LiNbO3 micro-platelets (mm long and 1 μm thick) have been obtained from a z-cut LiNbO3 wafer by ion implantation and thermal treatment. X-ray diffraction measurement has proved that they have a single crystal structure. Their surface roughness and film quality have been investigated by atomic force microscope and field emission scanning electron microscope. These micro-platelets are transferable and bondable to other materials which require material properties of LiNbO3. They have been transferred, positioned and bonded to SiO2/LiNbO3, SiO2/Si, and Si-on-insulator (SOI: Si/SiO2/Si) by direct bonding method with optimum annealing conditions. For SiO2/Si and SOI substrates, there were large thermal mismatch between LiNbO3 and Si. They were, however, bonded at high temperature since these ultra thin micro-platelets were flexible and stretchable. Finally, to realize multifunctional SOI applications, a hybrid structure of LiNbO3 film and Si waveguide has been demonstrated.