Model of electronic states at the Si-SiO2interface

Abstract

The electronic properties of the interface between crystalline Si and its amorphous oxide ${\mathrm{SiO}}_2$ have been studied within the tight-binding approximation by saturating the dangling bonds in three different surfaces (111), (110), and (100) of a semi-infinite Si crystal with ${\mathrm{SiO}}_2$ Bethe lattices. The localized states due to isolated dangling bonds in the interfaces ($P_b$ centers) are found to be roughly at the same energy, in the Si gap for the (111) and (110) cases, but the (100) interface differs substantially from the other two. It is also found that the value of the site-energy interaction parameter on the Si defect site is important in determining the energy of the defect state.