Isotopically pure single crystal epitaxial diamond films and their preparation

摘要

The present invention is directed to the production of single-crystal diamond consisting of isotopically pure carbon-12 or carbon-13. The product is believed to be like that diamond product in application Serial No. 448,469, but is made by a different method. In the present invention, isotopically pure single-crystal diamond is grown on a single crystal substrate directly from isotopically pure carbon-12 or carbon-13. One method for forming isotopically pure single-crystal diamond comprises the steps of placing in a reaction chamber a single crystal substrate heated to an elevated CVD diamond-forming temperature. A gaseous mixture of hydrogen and a hydrocarbon of isotopically pure carbon-12 or carbon-13 is provided in the chamber. The gaseous mixture then is at least partially decomposed in the chamber to form an isotopically-pure single crystal diamond layer on the single crystal substrate disposed therein. The thus-formed isotopically-pure single crystal diamond layer optionally may be removed from the single crystal substrate. Another method for forming isotopically-pure single-crystal diamond comprises diffusing isotopically-pure carbon-12 or carbon-13 through a metallic catalyst/solvent under high pressure to a region containing a single crystal substrate to form an isotopically-pure single-crystal diamond layer on said single crystal substrate. The single crystal substrate is stable under the high pressure and elevated temperatures used during the diffusion process. The single crystal substrates optionally may be diamond, including the isotopically-pure single-crystal diamond films formed by the inventive method disclosed herein, thus forming multi-layered diamond structures.