Frequency dependence of the effective series capacitance of metal–Ta2O5/SiO2–Si structures

Abstract

The frequency dependence of the capacitance in accumulation of the metal–Ta2O5/SiO2–Si structures was studied in the frequency range from 20 Hz to 1 MHz. The capacitances at low and high frequencies differ significantly even in accumulation where the interface states do not affect the measurement. The experimentally observed frequency dependence was explained by the different conductivities of the insulating layers, the bulk Ta2O5 and the interfacial SiO2, due to the difference in the corresponding conduction mechanisms. A five-element equivalent circuit model was proposed for explaining the observed dependences. A qualitative agreement of the theoretical to the experimental results is observed almost over the entire measurement range.