The gas-dynamic synthesis of diamond by thermal activation

The study presents results on deposition of diamond structures from high-velocity flows of carbon-containing a gas mixture activated by hot surfaces. Important problems were solved by creation of the reactor using a spiral of heat-resistant material, inserted into the chamber with an inlet nozzle. The possibilities of diamond synthesis in wide parameters ranges (pressure from 10(-4) to 100Torr, flow rates from 500 to 3000sccm, substrate temperature from 1100 to 1600K) have been studied experimentally. For analysis of the hydrogen flow, the direct simulation Monte Carlo (DSMC) method was used. The activation-deactivation influence of reactor surfaces has been taken into account. The results of diamond crystal synthesis are presented for the cases of joint and separated H-2 and CH4 gas delivery. Due to retaining the catalytic tungsten properties in the case of separated gas delivery, an increasing growth rate of diamond crystals was discovered. (C) 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim