The preparation of Au/Bi4Ti3O12/SiO2/n-Si structures, investigation of the electrical and dielectric properties based on frequency and temperature

The frequency and temperature dependent capacitance-voltage (C-V) and conductance-voltage (G/w-V) characteristics of the metal-ferroelectricinsulator- semiconductor (MFIS) structure were investigated by considering series resistance (Rs) and surface state (Nss) effects in the frequency and temperature ranges of 1 kHz-5 MHz and 80-400 K, respectively. The values of Nss and Rs were determined to be strongly dependent on the frequency and temperature. The C-V-f and G/w-V-f characteristics of Au/Bi4Ti3O12/SiO2/n-Si structure show fairly large frequency dispersion especially at low frequencies, the C-V-T and G/w-V-T plots exhibit anomalous peaks at forward bias due to Rs and Nss. These peak positions shift from accumulation to inversion region and the maximum values of the capacitance and conductance increase with increasing temperature. The measured capacitance (Cm) and conductance (Gm/w) values were corrected for the effect of series resistance to obtain the real capacitance and conductance of MFIS structure. The Rs-V plots exhibit anomalous peaks between inversion and depletion regions at each frequency and peak positions shift towards positive bias with increasing frequency. The C- 2-V plot gives a straight line in wide voltage region, indicating that interface states and inversion layer charges cannot follow the ac signal in the depletion region. The Nss decreases exponentially with increasing frequency. The C-V and vii G/w-V characteristics show the expected behavior due to Nss in equilibrium with the semiconductor. Dielectric constant (C'), dielectric loss (C'') and, dielectric loss tangent (tanE) were studied for MFIS structure and calculated from C-V and G/w-V measurements. The dielectric parameters were quite sensitive to temperature and frequency at relatively high temperatures and at low frequencies. The C' and C'' were decreasing with increasing frequency while increasing with increasing temperature. The interfacial polarization can be more easily occurred at low frequencies, and the number of interface states density between semiconductor/insulator interfaces, consequently, contributes to the improvement of dielectric properties of MFIS structure.