Illumination intensity effects on the electrical characteristics of Al-TiW-Pd2Si/n-Si Schottky structures have been investigated in this study for the first time. The electrical parameters such as ideality factor (n), zero-bias-barrier height (Phi(B0)), series resistance (R-s), depletion layer width (W-D) and dopping concentration (N-D) of Al-TiW-Pd2Si/n-Si Schottky barrier diodes (SBDs) have been investigated by using the forward and reverse bias current-voltage (I-V), capacitance-voltage (C-V) and conductance-voltage (G/omega-V) measurements in dark and under illumination conditions at room temperature. The values of C and G/omega increase with increasing illumination intensity due to the illumination induced electron-hole pairs in the depletion region. The density of interface states (N-ss) distribution profiles as a function of (E-c-E-ss) was extracted from the forward I-V measurements by taking into account the bias dependence of the effective barrier heights (Phi(e)) for device in dark and under various illumination intensities. The high values of N-ss were responsible for the nonideal behavior of I-V, C-V and G/omega characteristics. The values of R-s obtained from Cheung and Nicollian methods decrease with increasing illumination intensity. The high values of n and R-s have been attributed to the particular distribution of N-ss surface preparation, inhomogeneity of interfacial layer and barrier height at metal/semiconductor (M/S) interface. As a result, the characteristics of SBD are affected not only in N-ss but also in R-s, and these two parameters strongly influence the electrical parameters. (C) 2010 Elsevier B.V. All rights reserved.