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The electron field emission (EFE) properties of microcrystalline diamond (MCD) films are significantly enhanced due to the Fe coating and post-annealing processes. The 900 C post-annealed Fe coated diamond films exhibit the best EFE properties, with a turn on field (E 0) of 3.42 V/lm and attain EFE current density (J e) of 170 lA/cm 2 at 7.5 V/lm. Scanning tunnelling spectroscopy (STS) in current imaging tunnelling spectroscopy mode clearly shows the increased number density of emission sites in Fe-coated and post-annealed MCD films than the as-prepared ones. Emission is seen from the boundaries of the Fe (or Fe 3 C) nanoparticles formed during the annealing process. In STS measurement, the normalized conductance dI=dV I=V versus V curves indicate nearly metallic band gap, at the boundaries of Fe (or Fe 3 C) nanoparticles. Microstructural analysis indicates that the mechanism for improved EFE properties is due to the formation of nanographite that surrounds the Fe (or Fe 3 C) nanoparticles. V

ZnO films were grown on interdigital transducer (IDT)/Corning 7059 glass substrates by RF planar magnetron sputtering using two-step fabrication methods for surface acoustic wave (SAW) applications. The crystalline structure of the as-deposited ZnO films was characterized by x-ray diffraction (XRD) and x-ray rocking curve analysis. The SAW properties, including coupling coefficient and insertion loss, were evaluated and compared with the theoretical results. ZnO films deposited by the two-step fabrication method exhibited a lower insertion loss and a closer agreement between the experimental coupling coefficients and the corresponding theoretical values in comparison with films deposited by the one-step fabrication method. The results could be useful in the design of high-coupling low-loss SAW devices.

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The electron field emission (EFE) properties of diamond films were markedly improved by Fe-coating and postannealing processes. Transmission electron microscopy examination indicated that the possible mechanism of enhancing the EFE behavior is the reaction of the Fe layer with diamond and the reprecipitation of the dissolved carbon species to form nanographite. Scanning electron micrographs showed that the Fe coating first formed Fe particles at 700 C and then reacted with diamond, forming iron carbide (Fe 3 C) at 800 C. The dissolution and reprecipitation processes occurred simultaneously during the postannealing process at higher temperatures (800-950 C), which leads to the formation of amorphous carbon when the postannealing temperature is low (800-850 C) and to that of nanographite when the postannealing temperature is high (900-950 C). The 900 C-postannealed diamond films exhibit the best EFE properties, which can be turned on at a field of E 0 ¼ 2:8 V/m, and attain an EFE current density of J e ¼ 21:4 A/cm 2 at 8 V/m. #