Vapor Deposition of Diamond

Abstract

Diamond synthesis under thermodynamic metastability has been shown to be feasible by vapor deposition using hydrocarbon-hydrogen mixed gases. Three different methods, i.e., modified CVD using a hot tungsten filament and plasma assisted vapor depositions using microwave (2, 450MHz) and rf (13.5MHz) power are employed. Typical growth conditions are : methane concentration, ca. 1%; total pressure, 10-60 Torr; temperature, 700-1000°C. Diamond can be grown on diamond as well as on non-diamond substrates including Si, Mo, W, Ta, SiO2, Al2O3 and BN. Structural identification of the deposits was performed by electron diffraction and Raman spectroscopy. Lattice spacings determined by RHEED agreed with those reported for diamond. X-ray diffraction pattern characteristic of diamond was observed for deposited films. Vapor-deposited diamond particles show well-defined morphology characteristic of diamond. They grow at a rate of 0.5-1μm/hr. The paticles are hard and readily give visible scratches on the surface of SiO2, Al2O3, B and B4C.