A Model of the Gate Capacitance of Surrounding Gate Transistors: Comparison With Double-Gate MOSFETs

Abstract

In this work, we develop a comprehensive model of the total gate capacitance (CG) of circular-cross-section surrounding gate transistors that accounts for both the insulator gate capacitance (Cins) and the inversion capacitance (Cinv). The accuracy of the model is checked with the results obtained from the numerical simulation of the structure. Using this model, we compare the CG/Cins ratio with that of double-gate (DG) transistors and study the degradation of the total gate capacitance of both devices as a function of the gate voltage and device size. It is shown that the CG/Cins ratio is higher in DGs, particularly for very small devices.