Chemical and electronic structure of SiO ₂ /Si interfacial transition layer

The chemical and electronic structures of SiO ₂ /Si(1 1 1) and SiO ₂ /Si(1 0 0) interfacial transition layers are reviewed. It will be shown, considering the penetration of electronic states from the Si substrate into SiO ₂ in the analysis of the thickness dependence of the energy loss of O 1 s photoelectrons measured with a probing depth of 0.41 nm, that energy barriers for valence electrons, which are almost comparable to those found in SiO ₂ , were formed when the oxide layer formed on Si(1 1 1) and Si(1 0 0) was thicker than 0.61 and 0.51 nm, respectively. In other words, the SiO ₂ /Si(1 1 1) and SiO ₂ /Si(1 0 0) interface defined with electronic band structure exists, respectively, in the oxide located effectively 0.61 and 0.51 nm away from the nominal interface defined with the atomic structure. In other words, incorporation of one atomic layer of oxygen at the interface does not form an electronic barrier. The extreme uniformity of the oxide layer formed on Si(1 0 0) was verified using synchrotron radiation excited high resolution XPS.