Defect formation and evolution in the step-flow growth of silicon carbide: A Monte Carlo study

A novel Monte Carlo kinetic model has been developed and implemented to predict growth rate regimes and defect formation for the homoepitaxial CVD growth of various SiC polytypes over different substrates. The model is an advancement with respect to standard Monte Carlo algorithms, allowing to simulate both epitaxial and defective structures. The model shows two different defects formation mechanisms depending on the off-angle cut of the initial substrate and on the growth rate. The 2D island nucleation represents the limiting process for large terraces, i.e. small off-angle cuts (4 degrees and below) and low deposition rates (∼12μm/h and below). Instead, for high deposition rates (∼100μm/h typical of the SiHCl3SiHCl3-based processes) the roughness of the step becomes of the order of the terrace width, so that local step bunching occurs, hindering the standard step-flow kinetic. This enhances the creation of local defects, being, these defects, associated essentially to vacancies. The simulations also indicated that the surface morphology after the growth process is the signature of the different growth regimes. A comparison between simulation results and experimental analysis of the surface structure by means of atomic force microscopy has been performed.