Au/ZnO/n-type Si device is obtained using atomic layer deposition (ALD) for ZnO layer, and some main electrical parameters are investigated, such as surface/interface state (N-ss), barrier height (Phi(b)), series resistance (R-s), donor concentration (N-d), and dielectric characterization depending on frequency or voltage. These parameters are acquired by use of impedance spectroscopy measurements at frequencies ranging from 10 kHz to 1 MHz and the direct current (DC) bias voltages in a range from -2 V to + 2 V at room temperature are used. The main electrical parameters and dielectric parameters, such as dielectric constant (epsilon'), dielectric loss (epsilon ''), loss tangent (tan delta), the real and imaginary parts of electric modulus (M' and M ''), and alternating current (AC) electrical conductivity (sigma) are affected by changing voltage and frequency. The characterizations show that some main electrical parameters usually decrease with increasing frequency because charge carriers at surface states have not enough time to fallow an external AC signal at high frequencies, and all dielectric parameters strongly depend on the voltage and frequency especially in the depletion and accumulation regions. Consequently, it can be concluded that interfacial polarization and interface charges can easily follow AC signal at low frequencies.