Plasma-enhanced chemical vapor deposition has been used for the deposition of diamond and diamond-like thin films during the last decade with great success. Here we present experimental evidence that a chemical vapor deposition technique can also be used to synthesize other forms of carbon including fullerenes and hydrocarbon polymers. The mechanism of diamond nucleation and fullerene formation appear closely related.Since the discovery that fullerenes form in supersonic molecular beams (7), many techniques (2-9) have been used to produce fullerenes. Out of these many techniques, carbon-arc and combustion methods have been used for commercial production of fullerenes. In the carbon-arc method, yields of 5% to 8% are common, and yields as high as 40% have been reported (JO). It has been a puzzle for some time how a molecule as complex as fullerene can be formed so readily. Various formation mechanisms have been proposed (11)(12)(13)(14). In particular the isolated pentagon rule (JPR) appears to explain many of the experimental observations.Here we present observations of fullerene formation using hot-filament CVD and microwave-enhanced CVD methods. The yields of fullerene-containing soot are low, even though the yields of fullerene from the soot are quite reasonable. Our goals in this research are: (a) to determine the relationship between fullerene formation and diamond nucleation, and (b) to shed light on fullerene formation mechanisms. ExperimentalHot filament CVD A schematic diagram of the apparatus (75, 16) used for this study is shown in Fig. 1. The chamber is constructed of stainless steel with a diameter of 35