Comparative study of the effect of different interlayer thicknesses on frequency dependent electric modulus and conductivity in Au/n-Si structures

•Three structures with different interlayer thicknesses were fabricated.•Frequency effect is more especially at depletion and accumulation regions.•Interlayer existence is highly dependent on modulus and conductivity.•Interlayer thickness increment has positive impact on conductivity. Frequency dependent capacitance (C) and conductance (G/ω) data for Au/n-Si structures fabricated at room temperature without interlayers and with 5 nm and 10 nm aluminium-oxide (Al2O3) interlayer thicknesses are investigated. The Al2O3 interlayers were deposited by atomic layer deposition. Data on the complex electric modulus (M*) and alternating current electrical conductivity (σac) values are acquired for the three structures in the 3 kHz-3 MHz frequency range between (-3 V) – (+5 V) bias interval and compared. It was observed that the C and G/ω values decreased with the increase in frequency and interlayer thickness and that the frequency increases as a result of polarization which also increases M*, especially in 5 nm and 10 nm interlayered structures. Frequency and interlayer thickness increment have a positive impact by increasing σac, while conductivity has been shown to be highly sensitive to the presence of an interlayer and to its thickness.