Halogen-assisted chemical vapor deposition of diamond

Abstract

The present invention is directed to a method for depositing diamond films and particles on a variety of substrates by flowing a gas or gas mixture capable of supplying (1) carbon, (2) hydrogen and (3) a halogen through a reactor over the substrate material. The reactant gases may be pre-mixed with an inert gas in order to keep the overall gas mixture composition low in volume percent of carbon and rich in hydrogen. Pre-treatment of the reactant gases to a high energy state is not required as it is in most prior art processes for chemical vapor deposition of diamond. Since pre-treatment is not required, the process may be applied to substrates of virtually any desired size, shape or configuration. The reactant gas mixture preferably is passed through a reactor, a first portion of which is heated to a temperature of from about 400.degree. C. to about 920.degree. C. and more preferably from about 800.degree. C. to about 920.degree. C. The substrate on which the diamond is to be grown is placed in the reactor in a zone that is maintained at a lower temperature of from about 250.degree. C. to about 750.degree. C., which is the preferred diamond growth temperature range. The process preferably is practiced at ambient pressures, although lower or higher pressures may be used. Significant amounts of pure diamond films and particles have been obtained in as little as eight hours. The purity of the diamond films and particles has been verified by Raman spectroscopy and powder x-ray diffraction techniques.