Synthesis of High Purity Diamond Single Crystal

Abstract

This paper presents the outline of the temperature gradient method at high pressures and high temperatures for the epitaxial growth of a high purity diamond single crystal. Several elimination techniques of the impurities (mainly nitrogen atoms) in a single crystal are discussed. High purity diamond single crystals, containing impurities as low as 0. 1 ppm, are successfully grown up to 1 or 2 carats by adding titanium and copper in the solvent bath in the temperature gradient method. In order to reduce the nitrogen content of a solvent bath, titanium is added as a nitrogen getter, while copper is added to decompose titanium-carbide which is contained in a crystal as bulky inclusion by adding of titanium.