Microwave plasma assisted synthesis of single crystal diamond at high pressures and high power densities

Summary form only given. It is now widely understood that CVD synthesized diamond quality and growth rates can be improved by using high power density microwave discharges operating at pressures above 160 Torr. Thus we have developed microwave plasma reactor designs and associated process methods that are both robust and are optimized for high pressure and high power density operation and thereby take advantage of the improved deposition chemistry and physics that exist in the high pressure (180-320 Torr) regime. Here we will present the single crystal diamond (SCD) synthesis performance of two 2-5 kW, 2.45 GHz microwave plasma assisted CVD reactor designs, Reactors B and C, that have been specifically designed and optimized for operation in the high pressure regime. The reactors have incorporated design features that are adaptable such as reactor tuning that allows discharge matching and also the control of the position, size and shape of the discharge. Reactor B has been described earlier and Reactor C further improves performance by increasing applicator size and by positioning the discharge away from the reactor walls. The experimental performance of the new reactor designs will be presented and will be compared with each other and with a related reactor, Reactor A, that operates at lower pressures of 10-160Torr.