IMPROVED DIAMOND DEPOSITION CELL

In a first embodiment of an improved diamond deposition cell, a chamber is evacuated to a low pressure and a graphite element in the chamber is heated to a selected high temperature and heats a substrate positioned within the chamber spaced by a selected gap from the graphite body to a selected lower temperature. Hydrogen or a mixture of hydrogen and hydrocarbon gas is admitted to the chamber and part of the hydrogen reacts with the hot graphite body to form atomic hydrogen and hydrocarbon gases. Hydrogen and hydrocarbon gases cycle repeatedly across the gap between the facing surfaces of the body and the substrate in the kinetic regime resulting in a net transfer of carbon to the substrate and its deposition as diamond crystals or film on the substrate. In a second embodiment, the graphite body is heated by combusting gases in a cavity therein. Products of such combustion, hydrogen and, optionally, additional hydrocarbon gas are admitted to the gap between the surfaces of the graphite body and the substrate. The temperatures of the facing surfaces, the pressure in the gap and the ratio of the constituent gasses result in carbon atoms being deposited on the substrate in the form of diamond film and other carbon products.