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ZnO films with c-axis (0002) orientation have been successfully grown by radio frequency magnetron sputtering on glass substrates. The alumina films were deposited on interdigital transducers/ZnO/glass substrates by electron beam evaporation to enhance the performance of the ZnO thin film surface acoustic wave (SAW) devices. The crystalline structure and surface roughness of the films were investigated by X-ray diffraction and atomic force microscopy, respectively. The phase velocity and coupling coefficient of SAW device were apparently increased when we increased the thickness of alumina film. The experimental result is beneficial to improve the characteristics of the ZnO thin film SAW devices on cheap glass substrates. [ABSTRACT FROM AUTHOR]

Abstract: ZnO films with c-axis (0002) orientation have been successfully grown by RF magnetron sputtering on Al2O3/glass substrates. The alumina films were deposited on glass substrates by electron beam evaporation. The crystalline structure and surface roughness of the films were investigated by X-ray diffraction and atomic force microscopy, respectively. The phase velocity and coupling coefficient of SAW device were apparently increased when we increased the thickness of alumina film. Besides, an excellent temperature coefficient of frequency of SAW device was obtained with increasing the thickness of alumina film. The experimental result is beneficial to improve the performance of the ZnO thin film SAW devices on cheap glass substrate with easier process and lower cost. [Copyright &y& Elsevier]

Abstract: Highly C-axis textured LiNbO3 thin films were grown on SiO2/Si substrates with a ZnO buffer layer by XeCl excimer pulsed laser deposition technique. We fixed the target–substrate spacing at 40mm, oxygen flow rate of 20sccm and the repetition rate of 5Hz, and then changed the substrate temperature, energy density and oxygen pressure to obtain the optimum deposition conditions. The effect of post-annealing process on improving the structural properties of the as-deposited LiNbO3 thin films was also studied. The ZnO buffer layers and LiNbO3 films were characterized by X-ray diffraction (XRD), atomic force microscopy and scanning electron microscopy to analyze their crystalline structure, surface roughness and surface morphology, respectively. For the optimum deposition parameters such as substrate temperature of 700°C, energy density of 4.6J/cm2 and oxygen pressure of 150Pa, the full width at half maximum intensity (FWHM) of LiNbO3(006) peak was 0.22°. The FWHM of LiNbO3(006) peak was further reduced to 0.19° via. in-situ post-treatment at 750°C for 30min. The results could be useful for integrating the surface acoustic wave device, optical waveguide and semiconductor device on the same Si substrate. [Copyright &y& Elsevier]

Abstract: ZnO films with c-axis (0002) orientation have been grown on SiO2/Si substrates with an Al2O3 buffer layer by radio frequency magnetron sputtering. Crystalline structures of the films were investigated by X-ray diffraction, atomic force microscopy and scanning electron microscopy. The center frequency of the surface acoustic wave (SAW) device with a 4.8 μm thick Al2O3 buffer layer was measured to be about 408 MHz, which was much higher than that (265 MHz) of ZnO/SiO2/Si structure and approaches that (435 MHz) of ZnO/sapphire. It is a possible way as an alternative for the sapphire substrate for the high frequency SAW device applications, and is also useful to integrate the semiconductor and high frequency SAW devices on the same Si substrate. [Copyright &y& Elsevier]

Abstract: Diamond-like carbon (DLC) film is a promising candidate for surface acoustic wave (SAW) device applications because of its higher acoustic velocity. A zinc oxide (ZnO) thin film has been deposited on DLC film/Si substrate by RF magnetron sputtering; the optimized parameters for the ZnO sputtering are RF power density of 0.55W/cm2, substrate temperature of 380°C, gas flow ratio (Ar/O2) of 5/1 and total sputter pressure of 1.33Pa. The results showed that when the thickness of the ZnO thin films was decreased, the phase velocity of the SAW devices increased significantly. [Copyright &y& Elsevier]

• Linear antenna chemical vapor deposition parameters were optimized for diamond growth on GaN surface. • Stage to antenna distance, temperature, microwave power input and modes were varied. • Electron microscope, Raman, infrared spectroscope revealed diamond on GaN film characteristics. • 320 °C temperature, 6.4 cm distance and 2 kW MW input power in pulse mode were the optimal conditions. • Uniform nanocrystalline diamond films deposited directly on GaN surface without substrate etching. The present work will systematically study the effect of different linear antenna microwave plasma enhanced chemical vapor deposition (LACVD) processing parameters on the optimal deposition of the diamond films. The low pressure and low temperatures of LACVD growth conditions is expected to deposit diamond films on otherwise reactive gallium nitride (GaN) surfaces, without any intermediate nitride buffer layer. First, the distances between the quartz tube and the samples put on the stage are varied (3–15 cm), which has a direct impact on the substrate temperature (415°–300 °C). Thereafter, the microwave input power was also altered (1.5–2.8 kW) to attain low substrate temperatures. It was found that 300 °C is the temperature limit, which can be attained by heating only with microwave plasma when the substrates are kept farthest (15 cm) away from the liner antenna quartz tube. An additional heater was used under the stage for rapidly achieving such minimum substrate temperature of 300 °C. Substrate heater was used for efficient growth of the diamond phase while using pulse mode frequency of microwave power input for optimization of the diamond films. The microstructure (plate-like and cauliflower-like) of the deposited nanocrystalline diamond (NCD) films and the cross-sectional images for thickness measurements was observed under the scanning electron microscope and the elemental analysis of the film surfaces was done by electron diffraction spectroscopy. Moreover, the diamond film quality and crystallinity were evaluated by Raman spectroscopy with 488 nm laser light. Diamond-on-GaN film results were compared with conventional Si substrate. Different LACVD reactor parameters like, antenna to stage distances, microwave input power in continuous wave mode, and growth temperatures have significant impacts on the grown films, both in terms of their quality and microstructure. It was found that the optimum deposition of nanocrystalline diamond film on GaN substrates without its surface etching was possible, under pulse mode (20 kHz, 45 % duty cycle) with 2 kW average input microwave power. [ABSTRACT FROM AUTHOR]