New insights into the mechanism of CVD diamond growth: Single crystal diamond in MW PECVD reactors

Abstract

CVD Diamond can now be deposited either in the form of single crystal homoepitaxial layers, or as polycrystalline films with crystal sizes ranging from mm, μm or nm, and with a variety of growth rates up to 100s of μm h − 1 depending upon deposition conditions. We previously developed a model which provides a coherent and unified picture that accounts for the observed growth rate, morphology, and crystal sizes, of all of these types of diamond. The model is based on competition between H atoms, CH 3 radicals and other C 1 radical species reacting with dangling bonds on the diamond surface. The approach leads to formulae for the diamond growth rate G and average crystallite size < d> that use as parameters the concentrations of H and CH x (0 ≤ x ≤ 3) near the growing diamond surface. We now extend the model to show that the basic approach can help explain the growth conditions required for single crystal diamond films at pressures of 100–200 Torr and high power densities.