Ag/Ru$_{0.03}$−PVA/$n$-Si structures were successfully prepared and their morphological and electrical properties were investigated. The obtained electrical results suggested that the complex dielectric constant ($\epsilon^* = \epsilon^{\prime} − j\epsilon^{\prime\prime}$), complex electric modulus $M^∗ = M^{\prime} + jM^{\prime\prime}$, loss tangent ($\tan \delta$) and alternating current (ac) electrical conductivity ($\sigma_{\rm ac}$) are all a strong function of the frequency ($f$) and applied voltage. The changes in these parameters are the results of the existence of the surface states ($N_{\rm ss}$) or interface traps ($D_{\rm it} = N_{\rm ss}$), interfacial polymer layer, surface and dipole polarizations and hopping mechanisms. The values of $\epsilon^{\prime}$ and $\epsilon^{\prime\prime}$ show a steep decline with increasing frequency and then reach a constant value at high frequency, whereas the increments of $M^{\prime}$ and $M^{\prime\prime}$ with frequency are exponential. The $\tan \delta$ vs. $\log f$ plot has a strong peak behaviour, especially in the accumulation region. These experimental results suggested that the Ru$_{0.03}$−PVA interfacial layer could be used as a high dielectric material instead of conventional materials.