Gas-source growth of group IV semiconductors: I. Si(001) nucleation mechanisms

The initial stages of gas-source growth of Si(001) using disilane have been investigated using a combination of elevated-temperature STM and atomistic modelling. The reaction pathway from the initial adsorption of disilane fragments up to the nucleation of short strings of epitaxial dimers is discussed. By the use of our STM to study disilane at the temperatures of interest, and atomistic modelling to calculate structural stability and significant activation barriers, we are able to propose a complete description of the mechanisms which underlie gas-source growth.