We have characterized TiN/Si and TiN/SiO2/Si structures by utilizing the variable energy positron beam spectroscopy (VEPBS) and x-ray photoelectron spectroscopy (XPS). Thin films of TiN were grown on SiO2/Si and Si by chemical vapor deposition and sputtering. Details of the electronic structure, microstructural defects, and interface are probed by implanting monoenergetic positrons at varying depths and analyzing the resulting positron-electron annihilation gamma rays. This analysis provides results for the positron diffusion length in different parts of the layered structure. Being sensitive to the presence of lattice defects, the positron diffusion length can be used to assess the quality of the film. The XPS measurements provide details about the elemental composition and interface in these materials.

We have deposited diamond films on Si〈111〉 using hot filament assisted chemical vapor deposition at low pressures ∼25 Torr. Diamond films deposited at different relative concentrations of methane (ranging from 0.25% to 2.0%) in methane-hydrogen mixtures have been characterized by Raman spectroscopy, scanning electron microscopy, and x-ray photoelectron spectroscopy. With varying methane concentration, Raman spectra show features characteristic of crystalline diamond, diamond-like carbon, and polycrystalline graphite. Scanning electron micrographs show densely packed diamond crystallites. SEM measurements made on diamond films grown as a function of time show that the median grain size of the diamond crystallites increases linearly with time during the initial phase of the growth. X-ray photoelectron spectroscopy reveals differences between the diamond sp3 covalent bonding and sp2 graphitic bonding as well as the extent of s-p hybridization as a function of methane concentration. The plasmon loss shoulder, characteristic of graphite, is absent from the spectrum of 0.25% methane concentration film. But it appears in the XPS spectra of films grown at higher concentrations.