PULSED ION-BEAM CHARACTERIZATION OF CVD DIAMOND SURFACES UNDER THIN-FILM DEPOSITION CONDITIONS

Diamond and diamond-like carbon have properties which in principle mak e them ideally suited to a wide variety of thin-film applications. The widespread use of diamond thin films, however, has been limited for a number of reasons related largely to the lack of understanding and co ntrol of the nucleation and growth processes. Real-time, in-situ studi es of the surface of the growing diamond film are experimentally diffi cult because these films are normally grown under a relatively high pr essure of hydrogen, and conventional surface analytical methods requir e an ultrahigh vacuum environment. Pulsed ion beam based analytical me thods with differentially pumped ion sources and particle detectors ar e able to characterize the uppermost atomic layer of a film during gro wth at ambient pressures in the range 0.7-27 Pa (4-6 orders of magnitu de higher than other surface-specific analytical methods). We describe here a system which has been developed for the purpose of determining the hydrogen concentration and bonding sites on diamond surfaces as a function of sample temperature and ambient hydrogen pressure under ho t-filament chemical vapor deposition (CVD) growth conditions. It is de monstrated that as the hydrogen partial pressure increases the saturat ion hydrogen coverage of the surface of a CVD diamond film increases, but that the saturation level depends on the atomic hydrogen concentra tion and substrate temperature. At the highest temperatures studied (7 00 degrees C), it was found that the surface hydrogen concentration di d not exceed 1/4 monolayer.