The Au/n-Si Schottky barrier diodes (SBDs) with 200-mum (sample D200) and 400-mum (sample D400) bulk thicknesses have been fabricated. The ideality factor and the barrier height have been calculated from the forward-bias current-voltage (I-V) characteristics of D200 and D400 SBDs. The energy distribution of the interface states and relaxation time are found from the capacitance-frequency (C-f) characteristics. The density of interface state and relaxation times have a (nearly constant) slow exponential rise with bias in the range of E-c -0.77 and E-c -0.47 eV from the midgap toward the bottom of the conductance band. Furthermore, the energy distribution of the interface states obtained from C-f characteristics has been compared with that obtained from the forward-bias I-V characteristics.