In this study, the effects of high permittivity interfacial Bi4Ti3O12 (BTO) layer deposition on the main electrical parameters; such as barrier height, series resistance, rectifying ratio, interface states and shunt resistance, of Al/p-Si structures are investigated using the currentevoltage (I-V) and admittance measurements (capacitance-voltage, C-V and conductance-voltage, G/omega-V) at 1 MHz and room temperature. I-V characteristics revealed that, due to BTO layer deposition, series resistance values that were calculated by both Ohm's law and Cheung's method decreased whereas shunt resistance values increased. Therefore, leakage current value decreased significantly by almost 35 times as a result of high permittivity interfacial BTO layer. Moreover, rectifying ratio was improved through BTO interfacial layer deposition. I-V data indicated that high permittivity interfacial BTO layer also led to an increase in barrier height. Same result was also obtained through C-V data. Obtained results showed that the performance of the device is considerably dependent on high permittivity BTO interfacial layer. (C) 2013 Elsevier B.V. All rights reserved.