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 (N-D), diffusion potential (V-D) and barrier height (Phi(B)(C-V)) values were obtained from the reverse bias C-2 - V plots for each frequency. C and G/omega values decrease with increasing frequency as almost exponential for each voltage and these changes in C and G/omega are considerably high at low frequencies due to the contribution of surface states (N-ss) to the measured C and G/omega. 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 (tau) were obtained from the conductance method and they range from 1.53 x 10(14) eV(-1) cm(-2) to 1.03 x 10(14) eV(-1) cm(-2) and 1.29 x 10(-4) s to 3.35 x 10(-5) s, respectively, in the energy range of (0.585 - E-v) - (0.899 - E-v) eV. The voltage dependent of N-ss was also obtained from C-HF - C-LF method. The obtained value of N-ss is about 10(14) eV(-1) cm(-2) order and these values are suitable for an electronic device.