Nanowire and nanocable junction capacitances: Results for metal and semiconducting oxides

Formulas are derived for Schottky junction and p-n junction capacitances of nanowires and nanocables (which includes the hollow case of nanotubes). Evaluation of these expressions for the very unusual metal oxide, metallic conductor RuO2, demonstrates that capacitance values occur in the aF range. Furthermore, for recently fabricated conductor RuO2/SiO2 nanocables as reported in the literature, we show that the junction capacitances are significantly lower than the intrinsic quantum capacitance. These formulas are of great interest for device applications, and the capacitance findings could also have huge implications for charge storage and energy conversion applications.