Characterization of the SiO2/Si interface by positron annihilation spectroscopy

The densification of SiO2 on silicon towards the interface, as already concluded in a recent work, is confirmed to exist in thinner oxides obtained by etching, and in a native oxide, too. Furthermore, an annihilation state is revealed in the thermally grown and etched, as well as a native, oxide which must resemble low quartz in its structure. A lower limit d = (2.2 +- 0.1) nm of the thickness of the interface layer resembling low quartz in its structure can be estimated. A variety of the state-of-the-art theoretical calculations to aid the experimental findings is summarized. It is discussed why the presented results corroborate the model of quasi-epitaxial oxide growth and pseudo-polymorphic relaxation of the grown oxide.