Order and disorder at the C-face of SiC: A hybrid surface reconstruction

In this Letter, we explore the potential energy surface (PES) of the 3 × 3 C-face of SiC by means of the density functional theory. Following an extensive and intuitive exploration, we propose a model for this surface reconstruction based on an all-silicon over-layer forming an ordered honeycomb-Kagome network. This model is compared to the available scanning tunneling microscope (STM) topographies and conductance maps. Our STM simulations reproduce the three main characteristics observed in the measurements, revealing the underlying complex and hybrid passivation scheme. Indeed, below the ordered over-layer, the competition between two incompatible properties of silicon induces a strong disorder in the charge transfer between unpassivated dangling bonds of different chemistry. This effect in conjunction with the glassy-like character of the PES explains why it has taken decades to provide an accurate atomistic representation for this structure.