Model of the epitaxial growth of SiC-polytypes under surface-stabilized conditions

Molecular beam epitaxial (MBE) experiments demonstrate that it is possible to achieve a controlled layer-by-layer growth of SiC polytypes at temperatures below 1000 degrees C under surface-stabilized conditions. It is of substantial importance to stabilize characteristic Si-rich superstructures by an alternate supply of Si and C, switching periodically between more Si-rich and less Si-rich surface superstructures. The MBE growth of SiC happens in two basic steps: Firstly, Si overlayers are grown on Sie. Secondly, the Si overlayers are carbonized under supply of C, leading to growth of SiC. On the basis of first principles calculations within the framework of density functional theory in the local density approximation, we derive an equilibrium phase diagram for various structural models which provide a theoretical framework to rationalize some of the experimental findings qualitatively.