Probing the transition layer at the SiO₂-Si interface using core level photoemission

High resolution Si 2p photoelectron spectra obtained with synchrotron radiation are used to determine the distribution of oxidation states in the intermediary layer at the SiO2-Si interface. A ratio of 0.4:0.3:0.3 is found for the Si3++ 1+ intensities independent of Si surface orientation and oxide thickness. The interface is not completely abrupt (5±1 Å width).