Reverse bias capacitance extraction from finite element semiconductor device models [varactors]

The purpose of this work is to produce physical finite element models of varactor structures. A silicon p-n device is described here and the finite element calculated potential and charge solutions are used to extract the capacitance parameter in reverse bias. The finite element system used shows great flexibility and allows a wide range of results to be readily extracted, and the structure to be modified and recalculated with little inconvenience. The significance of this work is to underpin the physical finite element modelling of varactor structures. The paper describes the physical device model, the finite element method and presents carrier density plots and illustrates the non-linear varactor operation. A novel analytic method for calculating capacitance is also presented and used to validate the numerical results.