Early stages of diamond growth by chemical-vapor deposition monitored both by electron spectroscopies and microstructural probes

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Abstract
We performed a complete study of the nucleation and growth kinetics of chemical-vapor-deposition (CVD) diamond on Si(100). The diamond film was grown using the microwave-assisted MWACVD method and the substrate was preliminary pretreated by ultrasonic agitation with 300 μm diamond grains, which provides a high nucleation density at saturation (≳108 cm−2). The evolution of the diamond particles coverage was investigated by two independent ways. The size distribution, mean size of the individual diamond particles, the surface coverage, and the nucleation density were monitored by scanning electron microscopy, including analysis of the pictures, and the overall carbon coverage was recorded by x-ray photoemission spectroscopy. Results agree to predict a break point in the growth law: Initially the kinetics obey a law in t1/3, whereas after about 30–45 min the behavior becomes linear. This is interpreted as a change of the rate limiting step of the growth which is governed by the surface coverage of diamond particles. At low diamond islands surface coverage (S≪0.04), the growth process is limited by an indirect route including the impingement onto the bare surface, surface diffusion of the reactive carbon species, and interface reactivity. At larger surface coverage, the route through reactivity of the diamond surface is preferred.