In this research, PVA (doped with 7% Zn) was sandwiched between Al and p-Si as a polymer interfacial layer. Voltage and frequency effect on the real and imaginary components of complex dielectric constant (epsilon' and epsilon ''), electric modulus (M' and M ''), loss tangent (tan delta) and electrical conductivity (sigma) of the MPS-type capacitor has been studied. Impedance spectroscopy method was used between 5 and 5000 kHz at room temperature. Almost all frequency-related parameters were found as quite susceptible, especially in the accumulation and depletion regions. These changes in real and imaginary components of dielectric properties in depletion region were attributed to the interface layer and dipole polarization, the existence of surface states (N-ss) and their relaxation time (tau), especially at low frequencies. But these changes in the accumulation region were attributed to the existence of interfacial layer and series resistance (R-s) of the capacitor owing to the voltage divided between them and capacitor. As a result, frequency, applied biases, interfacial polymer layer, polarization processes, N-ss and R-s of the capacitor are more effective on the values of epsilon', epsilon '', tan delta, M', M '' and sigma. Therefore, the effects of them must be considered in determining the dielectric parameters, electric modulus, conductivity and conduction mechanisms in the capacitors with and without an interfacial layer such as insulator/oxide, polymer, ferroelectric materials.