Zinc oxide (ZnO) films have been deposited on 1 μm SiO2/Si (100) substrates by rf magnetron sputtering. Using a sputtering gas of pure oxygen, a pressure regime is found in which the ZnO films grow on room temperature substrates with a single (0001) orientation, small grains (crystallite sizes ∼10–15 nm), and high intrinsic biaxial compressive stress (∼6 GPa). The effects of post-deposition annealing these films in air was investigated over a range of temperatures (200–1000 °C) and durations (2–2000 min). Annealing resulted in lower biaxial compressive stresses and increased average crystallite sizes in all films. Additional ZnO grain orientations were detected only after annealing above 500 °C for longer than 90 min, and the results are interpreted in terms of film recrystallization. Consequently, a relatively rapid thermal anneal at 1000 °C for 5 min caused grain recovery without recrystallization, resulting in maximum stress reduction (90%–100% of stress was relieved and average crystallized size tripled) while maintaining the original film orientation. The film surface area—measured by atomic force microscopy—decreased by up to 25% during annealing. X-ray photoelectron spectroscopy results indicate that although the surfaces of as-deposited films have a slight excess of oxygen, annealing as low as 200 °C results in a stoichiometric ZnO surface. High values of electrical resistivity (∼105 Ω cm) measured across the thickness of unannealed oriented films indicate low levels of elemental zinc clusters in the film bulk.

Polycrystalline (0001)-oriented thin films of ZnO (thickness 120 nm) were deposited by rf magnetron sputtering and post-deposition annealed at 500 °C in oxygen (1 atm). The films were subsequently implanted with copper at doses over the range 1016 to 1017 ions/cm2. X-ray diffraction (XRD) indicates the compressive intrinsic film stress is largely relieved by the preimplantation anneal, and does not change when implanted or when further annealed after implantation, suggesting that the dominant cause of intrinsic stress is the atomic packing density rather than the crystallographic defect density. Resistivity measurements indicate that annealing of pure ZnO films causes the perpendicular resistivity to increase from 1.3 × 105 Ω · cm to 5 × 1010 Ω · cm. Copper implantation results in a lower resistivity of the order of 107 Ω · cm, but subsequent annealing actually increases resistivity beyond that of annealed nonimplanted ZnO to 3 × 1012 Ω · cm. It is proposed that copper increases the resistivity of those annealed films by trapping free electrons with the Cu 3d hole state occurring in CuO (formed predominantly during annealing). In order to check this, the oxidation state of the implanted copper was studied before and after annealing by x-ray photoelectron spectroscopy (XPS) and extended x-ray absorption fine structure (EXAFS). Three oxidation states of copper (Cu0, Cu1+, Cu2+) are detected in the implanted films, and postimplantation annealing results in oxidation of copper to the Cu2+ state, confirming that the presence of CuO in ZnO is associated with increased resistivity.

The intrinsic compressive stress in thin carbon films up to 350 nm in thickness, deposited on Si(100) substrates via dc magnetron sputtering, has been measured using ex situ optical interferometry. A plateau value in compressive stress (∼1.5×109 Pa) is observed for carbon films thicker than 85 nm, but an anomalously large stress (up to 50% increase) occurs for film thicknesses between 18 and 85 nm. The carbon film stress data are interpreted in terms of a simple structural model in which the average film density influences the macroscopic stress. Ultrathin carbon films (<10 nm) in the initial stages of growth were further investigated by atomic force microscopy (AFM) and x-ray photoelectron spectroscopy (XPS). AFM images of ∼1-nm-thick carbon films and uncoated substrates reveal topographic features with average heights of 4 and 1.5 Å, respectively, but no obvious island film growth structures. XPS measurements, in which the native SiO2 peak is used as a marker of exposed substrate area, suggest that films of ≤2 nm thickness are not continuous. The reported enhanced film stresses are therefore associated with a continuous film structure.

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The germanosilicate glass core (GeO,SiO,) of an optical fibre preform has been analysed and imaged using small-spot (-450 pm) x-ray photoelectron spectroscopy (XPS). The germanium oxide was most readily detected in the glass preform sample using the AI K, x-ray-induced Ge L,MM Auger feature. The observed Ge L,MM lineshape and estimated oxidation state shift of 8.8 eV with respect to pure germanium indicate that the germanium is predominantly in the form of GeO, (+ 4 oxidation state) within the germanosilicate core. Argon ion etching was found to sputter preferentially the oxygen from the glass, and the observed changes in Ge L,MM Auger lineshapes suggest that suboxide defects (GeO) are produced. Quantitative XPS images and linescans were used to map the spatial distribution of germanium within the preform and were in good agreement with measured refractive index profiles.