Growth of diamond film on single crystal lithium niobate for surface acoustic wave devices

Single crystalline lithium niobate thin films on diamond are useful for surface acoustic wave devices that operate at gigahertz frequency. The differences in the atomic bonding and crystalline structure between the lithium niobate and diamond and the high interfacial energy were responsible for formation of microcrystalline films of lithium niobate deposited on polycrystalline diamond. We have carried out growth of continuous diamond layer on single crystal lithium niobate by microwave chemical vapor deposition to overcome the above deficiencies. The temperature of the substrate during deposition has been maintained near 700 °C to reduce the loss of lithium from lithium niobate and to reduce the thermal stresses. Characterization by x-ray diffraction and Raman spectroscopy showed that the lithium niobate lattice is preserved without incorporation of carbon and the diamond layer is free from graphitic carbon. The integrated lithium niobate-diamond layered structure is shown to be suitable for surface acoustic wave devices.