Nitrogen compounds and their influence on diamond deposition in flames

The influence of nitrogen-containing species on the growth of diamond films is well-established in microwave and hot filament chemical vapour depositi on (CVD) systems. Here, diamond CVD was investigated in atmospheric acetyle ne-oxygen flames doped with N-containing species [N-2, N2O, NH3, N(CH3)(3)] . Small amounts of these additives increase the growth rate, while higher c oncentrations lead to preferential sp(2) carbon deposition. The growth-effe ctive amount of N-additive decreases by more than an order of magnitude in the sequence N-2 > N(CH3)(3) congruent to N2O > NH3. Simulation of the gas phase chemistry in a stagnation-flow geometry shows that the transformation of the additives towards HCN, NO and N is strongly correlated with growth enhancement and film quality decrease.