Search

Hard, relatively transparent, amorphous carbon films have potential applications as wear‐resistant coatings, including those in the optical industry. We have investigated some of the effects of elevated temperature on these films, deposited by glow discharge from methane. Differential scanning calorimetry (DSC) has shown a broad, asymmetric, exothermic peak at about 550 °C and a larger energy release at about 750 °C. The latter corresponds to a structural transformation (graphitization) and the sample becomes soft and black. The former appears to correspond to the release of hydrogen, similar to Si:H films. An analysis shows that the energy released, as measured in the DSC, is consistent with literature values for the energy of chemisorbed H on carbon and for the amount of ‘‘unbonded’’ H observed from a‐carbon films. Models are presented for the film structures needed to account for this chemisorbed H and for the film densities and transmission electron microscope images.

Thin (

Ti and TiOx films have been made by vacuum and reactive evaporation, respectively, using electron beam heating. However, magnetron sputtering of Ti and its oxides is of interest because of the system’s simplicity and possible applications in the semiconductor and metallurgical industries. An investigation has been made into the discharge and deposition characteristics of a planar magnetron. Using a water‐cooled Ti target operated at up to 1200 W in Ar and Ar+O2 mixtures, the results obtained show that V/I curves fall into two groups. Thus a high operating voltage is needed at either a low input power or high O2‐gas content which is the characteristic mode for high oxidized film growth. High power inputs (even in the presence of a 25% O2 content) or low O2 content resulted in a low operating voltage and the growth of substantially metallic films. The effects of O2 on the discharge characteristic are briefly considered. Deposition rate curves as a function of power input for different gas mixtures are prese...

Low secondary electron emission yield (1–1.3), low radio‐frequency (rf) loss films are of interest as coatings for alumina ceramic high power klystron windows. Very thin (15–50 A) Ti and TiN layers have been previously used with success in klystron tubes operating at lower power levels (

We have developed a new technique to produce diamondlike carbon films in an rf system with water‐cooled electrodes. Hydrocarbon gas is leaked into the experimental chamber through the upper electrode which is a Pyrex cylinder inside a coil forming an rf oven. The gas (CH4) undergoes ionization/dissociation in one rf field, within an axial magnetic field. A circular water‐cooled electrode supports the substrate to be coated, and is powered from a second rf generator, developing a negative self‐bias on the substrate. Thus dissociation and ion production at the upper electrode and ion acceleration by the lower electrode could be separately controlled to optimize the film properties. It is shown that low stress, highly dense carbon films can be deposited by this method. Information is also given on bulk and surface properties as well as modification of these properties by the deposition conditions.

For pt.I see ibid., vol.11, p.2907, 1978. Experiments are described using a cylindrical sector energy analyser to measure the stopping power of 5-10 mu g cm-2 carbon foils for atomic and molecular hydrogen ions. The incident energies of the ions varied between 100 and 300 keV amu-1 and precautions were taken to avoid foil thickening due to contamination effects. A ratio of the stopping for H2+ ions to that for protons of 1.06+or-0.03 was obtained rather than values up to 1.3 suggested in the literature. Stopping powers for protons at the lower energies were observed to be higher than those given in tabulated data.

Klystrons manufactured at the Stanford Linear Accelerator Center are typically baked at temperatures of 550 °C for times as long as 200 h. During these long bakeouts the copper‐gasketed type 304 stainless steel flange joints (seven in all) diffusion bond so intimately that the flanges can be separated only with a jacking fixture, and copper is left on the sealing surfaces. Removal of this copper necessitates the use of abrasive materials, which can result in contamination of the klystron body and compromise its reuse. We report on the use of 50 and 150 A TiN thin films as a diffusion barrier between the Cu gasket and the stainless‐steel flange.

Diamondlike carbon films of 5−15 nm were deposited on copper gaskets which were sealed in 304−stainless steel flanges. The carbon films acted as a diffusion barrier during high temperature bakeout (550 °C at 1 x 10−5 Torr for up to 200 hours) which prevented carbon diffusion into the copper. (AIP)