Simulating (100) diamond chemical vapour deposition using a 3D kinetic Monte Carlo code with a tetrahedral model for diamond

An on-lattice, N-fold, variable-time-step, periodic kinetic Monte Carlo model for {100} chemical vapour deposition (CVD) diamond growth has been developed using a 3-dimensional fully tetrahedral model for the diamond lattice. The growth model supports adsorption and incorporation of CHx species at monoradical and biradical dimer and trough sites. Once CHx has been incorporated into the lattice as a CH2 bridge, they can be rapidly etched back into the gas phase using a preferential-etching mechanism, or migrate across the surface until they eventually fuse and add to the bulk. The new 3D model has enabled three migration events to be specified and modelled in more detail: adjacent dimer migration, migration into vacant trough sites and migration down atomic steps. Specific dimer-creation and dimer-breaking processes have also now been added to the 3D model, and these dimer reconstructions on the surface are now modelled explicitly. Inclusion of both mechanisms simultaneously increased predicted growth rates and decreased roughness for nanocrystalline and microcrystalline diamond growth conditions. The conclusion is that future kMC models need to include the three migration events as well as models for dimer making and breaking processes if they are to simulate diamond growth more accurately.