Rapid doping of combustion flame CVD diamonds using supersonic expanding nitrogen plasma jets

In order to develop an easy and rapid elements-doped diamond film synthesis process, as a basic study, rapid diamond film deposition using combustion flame CVD and nitriding of the diamonds using supersonic expanding nitrogen plasma jets were carried out. The supersonic expanding plasma jets can be used as low-temperature plasma jets with high chemical reactivity due to supersonic adiabatic expansion and frozen flow. Actually, nitriding of titanium, steel and aluminum using these plasma jets were successfully carried out in our previous study. Consequently, by varying deposition conditions during diamond deposition, diamond particles could be deposited densely during only 20 min of deposition though it was difficult to deposit diamond particles densely under constant deposition conditions. Besides, though no nitride was produced in the case of pure nitrogen plasma jets, the color of diamonds varied from transparent to black during the operation and carbon nitride could be investigated in the plasma jets-irradiated diamonds using XRD in the case of hydrogen/nitrogen plasma jets. From these results, using hydrogen/nitrogen mixture plasma jets, nitrogen-doped diamonds could be produced by means of these techniques and the process was found to have high potential for elements-doped diamond synthesis. (C) 2004 Elsevier Ltd. All rights reserved.