Frequency and voltage dependence of dielectric properties,complex electric modulus,and electrical conductivity in Au/7% graphene doped‐PVA/n‐Si (MPS) structures

In order to increase the capacitance of Au/n‐Si (MS) structure, 7% graphene doped PVA was coated on n‐Si as an interfacial layer. The measured data of capacitance (C) and conductance (G/ω) of Au/7% graphene doped‐PVA/n‐Si (MPS) structure was utilized for the calculation of real and imaginary parts of complex permittivity (ε^* = ε′ ? jε″), loss tangent (tanδ), complex electric modulus (M^* = M′ + jM″), and electrical conductivity (σ). The admittance measurements (C and G/ω) were carried out in the frequency range of 0.5 kHz to 1 MHz at room temperature. Frequency dependence of the dielectric constant (ε′), dielectric loss (ε″) and tanδ shows a dispersive behavior at low frequencies. This behavior was explained by Maxwell–Wagner relaxation. Due to the dipolar and the interfacial polarizations, as well as the surface states (N_ss) and the interfacial PVA layer, the parameters exhibited a strong dependence on frequency and applied bias voltage. The σ versus log(f) plot exhibited both low and high frequency dispersion phenomena such that at low frequencies σ value corresponding to the dc conductivity (σ_dc), but at high frequencies it corresponds to the ac conductivity (σ_ac). M′ and M″, both, have low values in the low frequency region. However, an increase is observed with the increasing frequency due to the short‐range mobility of charge carriers. As a result, the change in dielectric parameters and electric modulus with frequency is the result of relaxation phenomena and surface states. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43827.