Gate capacitance of cylindrical nanowires with elliptical cross-sections

We investigate gate capacitance of cylindrical nanowires with elliptical cross-sections because most fabricated Si nanowires have elliptical cross-sections. We derive an exact result for the capacitance of confocal elliptical capacitors and an approximate expression for the capacitance of conformal elliptical capacitors. Using numerical simulations for conformal elliptical capacitors, we show that the analytical results for the confocal and conformal elliptical capacitors are within 5% of the numerical values for eccentricity <0.85. We also provide correction factors to the analytical results that match the numerical conformal elliptical capacitances to within 5% for all values of eccentricity. © 2011 American Institute of Physics.