Surface chemistry of CVD diamond: linking the nanoscale and mesoscale modelling hierarchies

Abstract

The β-scission growth mechanism at the diamond (100)(2×1) surface is studied by a combination of nanoscale ab-initio LDA/GGA and semiempirical tight-binding techniques to provide the necessary input into the mesoscale variable time step Kinetic Monte-Carlo (KMC) simulations of CVD diamond growth. The reaction path of the beta-scission reaction is critically examined and the activation barrier of the reverse etching of the methylene adsorbate is deduced. Our quantum mechanical calculations support a previous semiempirical PM3 study confirming that the molecular mechanics values for the enthalpy of the reaction are a factor of 2 wrong. This conclusion provides strong support for the preferential etching mechanism introduced into KMC to predict experimentally measured growth rates.