Hydrogen and (formula presented) defects at the (formula presented) interface: an ab initio cluster study

Employing ab initio density functional methods and atomistic cluster models, we investigate the properties of (Formula presented) defects and their interactions with hydrogen at the (Formula presented) interface. Our calculated hyperfine parameters agree quantitatively with experiments indicating that the (Formula presented) defect is a silicon dangling bond at the silicon side of the interface. We calculate the local minimum energy structures for one and two hydrogen atoms interacting with the (Formula presented) defect. From these calculations, we derive reaction energies for (Formula presented) adsorption and H desorption. Comparing our results to experimentally derived activation barriers, we suggest different atomistic mechanisms for the observed reactions.