High Rate, High Quality, Diamond Synthesis by the Combustion Flame Process

ABSTRACTAmong the various low pressure techniques being developed for the synthesis of diamond films and bulk diamond slabs the combustion flame synthesis process has some distinct advantages. In this approach the combustion reaction between acetylene and oxygen is utilized to generate the requisite energy to activate excess acetylene in the gas mix leading to the deposition of diamond films on a temperature controlled substrate brought into contact with the flame. Other diamond synthesis approaches, such as microwave enhanced and the filament assisted chemical vapor deposition processes, and the various arc jet techniques utilize mixtures of hydrogen and methane as the process gases. Oxygen and oxidizing specie ( such as OH radicals) in the flame ambient may be much more effective than atomic hydrogen in promoting the growth of diamond over the growth of graphite and other non- diamond forms of carbon. In addition this technique enables the growth of diamond at high rates and is relatively easily scaled for large area synthesis. In this paper a discussion of this technique is presented drawing upon recent research by the authors as well as published work to present a general discussion of the issues involved in the development of this technique of low pressure diamond synthesis.