Articles you may be interested inEpitaxial Sr 1.8 Ca 0.2 NaNb 5 O 15 thin film waveguides grown by pulsed laser deposition: Optical properties and microstructure

Thick films of lithium niobate (LiNbO3) have been epitaxially grown on sapphire substrates by multistep radio-frequency magnetron sputtering. We have investigated the optical properties of the deposited layers by the m-line spectroscopy technique. The relationship between the film-substrate interface, the surface morphology of the LiNbO3 layer, and the optical measurements has been carefully established. Since this optical technique is sensitive to material defects, a detectable degradation of the optical data is observed when the microstructure of the LiNbO3 film changes. In particular, the angular width of the excited optical guided modes (Δθ) varies with the film thickness. This agrees perfectly with the evolution of the surface roughness as a function of the film thickness. We report a surface roughness rms of 2 nm corresponding to an angular width Δθ of 0.1° for the TE0 mode. The accuracy and the sensitivity of this technique can be advantageously compared to the classical tool of atomic force microscopy.

Articles you may be interested inHigh-frequency surface acoustic wave devices based on LiNbO 3 ∕ diamond multilayered structure Appl. Phys. Lett. 87, 213503 (2005); 10.1063/1.2135383 Temperature stable LiNb O 3 surface acoustic wave device with diode sputtered amorphous Te O 2 over-layer Appl.Fabrication of c-axis oriented ZnO/AlN thin films prepared by radio frequency reactive sputtering and development of ZnO/AlN layered structure surface acoustic wave devices

Lithium niobate (LiNbO 3 ) films have been grown at 490 C on diamond-coated silicon substrates by radio-frequency magnetron sputtering. A multi-step process was developed to produce thick layers on diamond with a good structure and a smooth morphology. To assess the structural quality of our films, we performed X-ray diffraction, transmission electron microscopy and atomic force microscopy of the films. The structure is conserved whatever the film thickness. A delay line structure of wavelength of 28 mm was realized and transducers were deposited on top of LiNbO 3 . The objective was to verify the high velocity in such a multi-layered structure. The first results indicated a SAW velocity estimated of 8200 m/s and a coupling factor was k 2 around 1%. The film growth, the technology and the electrical measurements are described in this paper.