Frequency dependent electrical characteristics of BiFeO3 MOS capacitors

• The C–V and G/ω–V characteristics of BiFeO3 MOS capacitor are frequency dependent.
• The C–V characteristics showed expected behavior for different frequencies.
• The behaviors of G/ω–V characteristics were different for low and high frequencies.
• The Ns, Rs and presence of domain wall may be reasons of this G/ω–V behavior.
• The results demonstrate that Rs and Ns can affect electrical characteristics of devices.

The frequency dependent electrical behavior of BiFeO3 MOS capacitors was studied in this work. BiFeO3 thin films were deposited on p-type Si (1 0 0) substrates at 0 °C by RF magnetron sputtering and the structures were investigated by XRD and SEM measurements. Electrical characteristics of the capacitors were determined by C–V and G/ω–V measurements for several frequencies from 10 kHz to 1 MHz. The results illustrate that the C–V and G/ω–V characteristics of the devices are sensitive to both frequency and voltage variations. C–V characteristic variations decrease with increasing frequency and are mainly resulting from the presence of interface states (Ns) between silicon and BiFeO3. The G/ω–V characteristics of devices were found to be different for low and high frequencies. Variations in G/ω–V characteristics in the low frequency regions (f < 500 kHz) decrease with increasing frequency, however, in high frequency regions they increase with increasing frequency. For high frequency (1 MHz) characteristics of the capacitor, the capacitance has been corrected by eliminating the effects of the series resistance (Rs) because of its negligible response to high frequency; however, for conductance measurements it cannot be ignored. The C–V and G/ω–V analysis demonstrate that Rs and Ns are important factors that can affect electrical characteristics of the capacitor.