High quality diamond thin films were deposited on different substrates at temperatures from 300 to 1000 °C by the microwave plasma enhanced chemical vapor deposition (MPCVD) system. The quality of deposited diamond films was improved by adding oxygen in the gas mixtures. Different ratios of methane to oxygen concentration in hydrogen at different temperatures have been studied. At high temperatures (800–1000 °C), the addition of oxygen will not only enhance the growth rate of deposited films but also extend the region of diamond formation. At low temperatures (<500 °C), the oxygen plays an important role in diamond film growth by preferentially etching the non-diamond carbon. Without the addition of oxygen, the films deposited at high temperatures (>900 °C) were either graphitic or diamond containing a large amount of graphitic or amorphous carbon and at low temperatures (<500 °C) were white, soot-like coatings which were easily scraped off. The quality of the deposited films was characterized by Raman spectroscopy and scanning electron microscopy.

Thin diamond films were deposited on silicon, MgO, fused silica, and soda lime silica glass at low temperature (the lowest temperature ∼365 °C) by microwave plasma-enhanced chemical vapor deposition. The films were identified as diamond by Raman spectroscopy. A Raman peak shift of several wave numbers to either lower or higher wave numbers due to the strain of the film is also observed. The film deposited on glass is highly transparent. The fine faceted crystals in the film are shown in scanning electron microscope micrographs.

By using surface-enhanced Raman spectroscopy it was possible to clearly identify very thin diamond and amorphous carbon coatings which were not detectable by normal Raman spectroscopy. A very small amount of silver was sputtered onto the surface of thin diamond depositions. Raman spectra measured through the silver layer exhibited the 1332 cm−1 diamond line and broadbands due to other forms of carbon. Raman scattering measured through silver coatings directly on the silicon substrate revealed extremely thin layers of amorphous carbon.

We link atomic-scale defects called E′ centers to radiation-induced leakage current (RILC). We present evidence that strongly suggests that RILC tolerance is processing dependent and that this tolerance appears to be correlated with lower E′ center generation. We furthermore note that in oxides subjected to quite high irradiation levels, the density of (generally electrically neutral) E′ centers is far greater than would be expected for the hole trap E′ centers involved in the radiation-induced positive charge buildup observed in thicker oxides.

Articles you may be interested inEffect of oxygen on growth and properties of diamond thin film deposited at low surface temperature Effect of the substrate state on the formation of diamond film in a low temperature microwaveplasmaenhanced chemical vapor deposition system J. Vac. Sci. Technol. A 13, 1619 (1995); 10.1116/1.579740Temperature dependence of growth rate for diamonds grown using a hot filament assisted chemical vapor deposition method at low substrate temperatures