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We report the deposition and structural characterization of nanostructural RuO2 on rutile (R)-TiO2/sapphire(100) templates by reactive radio frequency magnetron sputtering. The micrographs of field-emission scanning electron microscopy and X-ray diffraction patterns of RuO2/R-TiO2 heteronanostructures indicated the growth of vertically aligned RuO2 (001) nanotubes (NTs) and/or V-shaped RuO2(101) nanowedges (NWs) on top of R-TiO2 nanorods (NRs). Transmission electron microscopy and selected-area electron diffractometry characterizations of the vertically aligned RuO2 NTs showed that the hollow RuO2 NTs with square cross section have open-end morphology with long axis directed along the [0 0 1] direction, while the V-shaped RuO2 NWs revealed that the nanowedges are crystalline RuO2 with twin plane of (101) and twin direction of 1 ¯ 01 at the V-junction. The probable mechanisms for the formation of well-aligned RuO2 nanocrystals on top of R-TiO2 NRs were discussed.

Large surface area IrO x nanofoils (IrO x NF) were deposited on multi-wall carbon nanotube (MWCNT) templates, forming IrO x /MWCNT nanocomposites, by reactive radio frequency magnetron sputtering using Ir metal target. The structural and spectroscopic properties of IrO x NF were characterized. The micrographs of field emission scanning electron microscopy showed the formation of foil-like structure for the as-deposited samples. Transmission electron microscopy analysis revealed the contiguous presence of glassy iridium oxide, iridium metal, and iridium dioxide nanocrystals in the foil. X-ray photoelectron spectroscopy analysis provided the information of the oxidation states and the stoichiometry of IrO x NF. Raman spectra revealed the amorphous-like phase of the as-deposited IrO x NF. The nanofoil structure provided ultra-high surface area for electrical charge storage which made the IrO x /MWCNT nanocomposites as an attractive candidate for the supercapacitor applications.

Well-aligned densely-packed rutile phase TiO 2 nanocrystals (NCs) have been grown on sapphire (100) and (012) substrates by reactive magnetron sputtering using Ti metal target. The surface morphology, structural and spectroscopic properties of the as-deposited NCs were characterized using field-emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and micro-Raman spectroscopy. FESEM micrographs reveal the growth of vertically aligned NCs on sapphire (100), whereas the NCs on sapphire (012) were grown with a tilt angle of ∼ 33° from the normal to substrate. The XRD results reveal TiO 2 NCs with either (002) orientation on sapphire (100) substrate or (101) orientation on sapphire (012) substrate. A strong substrate effect on the alignment of the TiO 2 NCs growth has been demonstrated and the probable mechanism for the formation of these NCs has been discussed. XPS analyses show the oxygen vs. titanium ratio of 2.0 ± 0.1 for the as-grown TiO 2 NCs. Raman spectra of NCs exhibit a slight redshift in the peak position and a small broadening in linewidth with respect to that of the bulk counterpart. The results indicate the formation of good quality of nanocrystalline rutile phase TiO 2 .

We report the preparation of vertically aligned one dimensional (1D) IrO2 nanocrystals (NCs) on LiNbO3 (100) by reactive magnetron sputtering using Ir metal target. The effects of sputtering conditions such as distance between gun and substrate, pressure, power of radio frequency generator and substrate temperature have been presented and discussed. The surface morphology, structural and spectroscopic properties of the as-grown NCs were characterized in detail using field emission scanning electron microscopy (FESEM), X-ray diffractometry (XRD), X-ray photoelectron spectroscopy (XPS) and micro-Raman scattering. FESEM micrographs reveal that vertically aligned NCs were grown on LiNbO3 (100) substrates. The XRD results indicate that the IrO2 NCs are (002) oriented on LiNbO3 (100). The probable mechanism for the formation of the vertically aligned 1D NCs has been discussed. The XPS examination shows the existence of extra features at higher-binding-energy sites of Ir 4f and O 1s which is a common property for IrO2 1D NCs. The red shift and asymmetric broadening of Raman lineshape have been analyzed and attributed to both the size effect and residual stress.

Reactive sticking coefficients (RSC) of silicon hydride radicals are evaluated, between 853 and 903 K, from simulating the film thickness contours of trenches deposited in a SiH4/Ar reaction system. The RSC values of SiH4, Si2H6 and Si3H8, calculated from the hydrogen desorption kinetics and the surface hydrogenation kinetics at each trench location, are used to estimate their contributions in film growth. The radical RSC values and concentration are the fitting parameters in the trench simulation, in which the sum of SiH4, Si2H6 and Si3H8 contributions is referred to a film-forming species of low sticking coefficient, and the radicals as the other species of high sticking coefficient. The correlated RSC value of the radicals, generally less than 1, is higher than that of silane by approximately five orders of magnitude. The radical RSC linearly increases with the surface fraction of dangling bonds θ. The extrapolated RSC value at θ=1 is unity, which suggests that a radical has probability of reaction with dangling bonds of unity. The deviation from this idealized value is due to a large percentage of the growing surface being hydrogen-passivated. The probability of the reaction of a radical with the hydrogen-terminated surface, which is extrapolated at θ=0, has an activation energy of 4.6 kcal/mol.