The various levels (5%, 10% and 15%) of Cu-doped TiO2 thin films were grown on the n-type silicon (Si) wafer by spin coating technique to obtain Al/(Cu:TiO2)/n-Si (MOS) capacitors. Both the real and imaginary components of complex dielectric (ϵ=ϵ′-jϵ′′), complex electric modulus (M-=M′+jM′′), loss tangent (tan δ) and alternating electrical conductivity (σac) of the obtained Al/(Cu:TiO2)n-Si (MOS) capacitors were studied by taking into account the effects of Cu-doping levels into TiO2 viaimpedance spectroscopy method (ISM) in the wide range voltage (±5V) and frequency (10kHz-1MHz). All the obtained dielectric parameters were obtained as strongly dependent on frequency, voltage and Cu doping level. The observed anomalous peak in the forward bias region both in the real and imaginary components of ϵ-, tan δ, complex electric modulus (M-) and σac were attributed to the Cu:TiO2 interlay er, series resistance (Rs), surface states (Nss), interfacial/surface and dipole polarizations. The higher values of ϵ′ at low and intermediate frequencies implied that Nss have enough time to follow external ac signal, and also dipoles respond to the applied field to reorient themselves. Consequently, the fabricated Al/(Cu:TiO2)n-Si can be successfully used as MOS capacitor or MOS-field-effect transistor (MOSFET) in the industrial applications in near future.