Flatband voltage in MOS structures for spatial fixed oxide charge distributions

This article reports and models the impact of fixed oxide charges distributed spatially in the gate oxide of a metal–oxide–semiconductor (MOS) structure on its flatband voltage. In general analyses, the location of fixed oxide charges is effectively considered at the oxide–semiconductor interface which results in a simpler expression of the flatband voltage. However, for applications where fixed oxide charge distribution is a deciding component, the effect of the measured fixed oxide charge distribution inside the gate oxide needs to be reflected in the expression. The one-dimensional model in this article is used to design and deploy a graphical user interface which enables one to compute the flatband voltage of a MOS structure for any distribution of fixed oxide charges in the gate oxide, inclusive of known functions (Gaussian, exponential, or others), and discrete coordinate-based distributions.