OPTIMIZING THE GAS-PHASE CHEMISTRY IN A DC ARCJET DIAMOND CHEMICAL-VAPOR-DEPOSITION REACTOR

The application of a thermally driven gas phase chemical mechanism to model the plasma chemistry in a d.c. arcjet diamond chemical vapor deposition reactor appears justified in light of the low measured electron temperatures and densities reported here. Based an the model predictions, several downstream CH4 injection schemes have been developed and are shown to produce diamond films which exhibit improved quality without a reduction in growth rate. Optical emission actinometry data are also presented which suggest that the H atom flux to the substrate in this reactor, under typical diamond growth conditions, is mass diffusion limited. This condition would impose a limitation on the attainable growth rate for the reactor.