Interface States Induced by Amorphous SiO₂ in MOS Structures

Abstract

In order to understand physical origin of interface states in MOS structures, model calculations of the interface states are carried out. The model of the ideal Si–SiO₂, interface is introduced. This model represents that the Si–SiO₂ interface is given as the boundary between two bonding-type materials and the intrinsic interface state is absent. It will be assumed that observed interface state is caused by the difference between real interface and the ideal one. The real boundary of MOS structures may be described approximately in terms of the crystalline Si and the amorphous SiO₂ with an ideal glassy structure. Based on the simple model of amorphous SiO₂, the density of interface states is calculated semi-qualitatively. The obtained results suggest that the interface states induced by the amorphous SiO₂ do not give the observed density of the interface states and the amorphous state of SiO may take into account this density.