Impedance spectroscopy of Au/TiO2/n-Si metal-insulator-semiconductor (MIS) capacitor

In this study, the electrical properties of Au/TiO2/n-Si metal-insulator-semiconductor (MIS) capacitor were investigated by impedance spectroscopy (IS) technique. Impedance measurements were performed in the frequency range of 10 Hz-1 MHz for various bias voltages. The Cole-Cole plots show a single dielectric relaxation. The equivalent circuit was estimated from the shape of the Cole-Cole plots. The equivalent circuit of the MIS capacitor consists of a parallel resistor (R-p) and capacitor (C-p) in series with a resistor (R-s). It is observed that the Cole-Cole plots indicate a semicircle. The parameters of the equivalent circuit were determined by fitting the impedance measurement data. While the R-p value decreases with increasing the bias voltage, the C-p and R-s value are almost independent of the bias voltage. From the variation of log(R-p) with log(V), the dominant conduction mechanism of the MIS capacitor was determined as space-charge limited current (SCLC) mechanism.