Frequency-Dependent Admittance Analysis of Au/n-Si Structure with CoSO4-PVP Interfacial Layer

A film of cobalt sulfate (CoSO 4 )-doped polyvinylpyrrolidone (PVP) blend was spin-coated on n -Si. Electrical measurements were conducted on the Au/ n -Si structure with the CoSO 4 -PVP film sandwiched between them. The frequency dispersion of the main electrical and dielectric parameters and the corresponding mechanisms were evaluated. The extra capacitance originating from the contribution of interface states ( N ss ) resulted in a fairly large frequency dispersion in C – V plots. These states also influence the carrier transport and conduction mechanism, thus the determination of real N ss values is crucial to evaluate the nonideal behavior of such plots. The values of N ss were calculated using the Hill–Coleman method. The dielectric constant ( ε ′) and dielectric loss ( ε ″) exhibited higher values in the low-frequency region as a result of interface and dipole polarization, while the alternating-current (AC) electrical conductivity ( σ ac ) generally decreased. The variation of the loss tangent with increasing frequency of the applied field confirmed the effect of some internal field within the CoSO 4 -PVP film accompanied by the external AC field.