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The Z–V measurements were performed in wide-range voltage (± 6 V), and then the real/imaginary parts of ε* (ε′, ε″), M* (M′, M″), Z* (Z′, Z″), tanδ, and σac values of the Al/p-Si structure with pure polyvinyl alcohol (PVA) (D1), 3% (D2), and 5% (D3) graphene-doped PVA interfacial-layer were calculated at four frequencies (1, 10, 100, and 1000 kHz). When the frequency in D2 and D3 structures was increased from 1 kHz to 1 MHz, the dielectric constant value changed from 32.47 to 5.12 and from 26.26 to 1.00, respectively. They have a strong frequency dependence due to the presence of interface traps (Nit), polarization types, and organic interlayers at low frequencies. The observed anomalous peak in the ε′ and ε″ versus voltage curves in the depletion zone is the result of re-structure/re-ordering molecules in these traps under voltage/electric-field, and Nit measured frequency (f = 1/T). As a result, the ε′ and ε″ will be given an excess value to their real-value at lower frequencies. Because Nit and dipoles do not have enough time to spin themselves in the direction of the electric field and follow the ac signal at high frequencies, they cannot contribute the true value of them. In general, series resistance (Rs) and the interfacial layer are effective in the accumulation zone, while Nit is effective in the depletion region. These findings demonstrate that pure and (Gr:PVA) polymer-films at the M/S interface can be employed successfully in place of standard oxide materials. According to the comparison of dielectric constants, electrical modulus, impedance, and ac conductivity of all three structures at 100 kHz and 1 MHz frequencies, 3% Gr doping to PVA increases interfacial characteristics. |
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