N–O related shallow donors in silicon: Stoichiometry investigations

For clarification of the unknown chemical composition of the electrically active N–O defects in silicon, an ingot with variable oxygen content and fixed nitrogen concentration was investigated by infrared spectroscopy. Shallow donor spectra taken at different sample positions, i.e., oxygen concentrations, show a strong oxygen influence on the absorption of the different N–O species, allowing determination of the number of oxygen atoms for each species via the corresponding mass-action law. From that, the energetically deepest defect N–O-5 is associated with a NO configuration, whereas the strongest complex N–O-3 has NO2 composition. Further members of the shallow donor family contain three oxygen atoms.