Au/n-type 4H-SiC diodes were fabricated and their electrical characteristics have been investigated by using the capacitance/conductance- voltage-frequency (C-V-f and G/w-V-f) measurements method at room temperature. The main parameters such as the doping atoms (ND), diffusion potential (VD) and barrier height (ΦB(C-V)) values were obtained from the reverse bias C-2-V plots for each frequency. C and G/ω values decrease with increasing frequency as almost exponential for each voltage and these changes in C and G/ω are considerably high at low frequencies due to the contribution of surface states (Nss) to the measured C and G/ω. The resistivity (Ri) versus V plots were also obtained by using the C and G data and they exhibit an anomalous peak which is corresponding to the depletion region at each frequencies and its magnitude decreases with increasing frequency. The energy density distribution of N ss and their relaxation time (τ) were obtained from the conductance method and they range from 1.53 × 1014 eV -1 cm-2 to 1.03 × 1014 eV-1 cm-2 and 1.29 × 10-4 s to 3.35 × 10 -5 s, respectively, in the energy range of (0.585-Ev) - (0.899-Ev) eV. The voltage dependent of Nss was also obtained from CHF - CLF method. The obtained value of Nss is about 1014 eV-1 cm-2 order and these values are suitable for an electronic device. © World Scientific Publishing Company.