The electronic and interface state density distribution properties obtained from current-voltage (I-V) and capacitance-voltage (C-V) characteristics of Au/n-type GaAs Schottky barrier diode (SBD) at room temperature was investigated. SBD parameters such as ideality factor (n), series resistance (R-S) and barrier height (Phi(IV)) were obtained from I-V and C-V measurements using Cheung's method. The diode parameters such as ideality factor, series resistance and barrier heights were found as 1.51-1.78, 7.597-8.167 Omega and 0.88-1.14 eV, respectively. The diode shows non-ideal I-V behaviour with an ideality factor greater than unity. Furthermore, the energy distribution of interface state density was determined from the forward bias I-V characteristics by taking into account the bias dependence of the effective barrier height. The results show the presence of thin interfacial layer between the metal and semiconductor. (c) 2006 Elsevier B.V. All rights reserved.