To show the effect of gamma radiation, Au/Polyvinyl Alcohol (Co, Zn-doped)/n-Si Schottky barrier diodes (SBDs) were exposed to Co-60 gamma-ray source at room temperature. These structures were investigated by using current-voltage (I-V), capacitance-voltage (C-V), and conductance-voltage (G/omega-V) measurement methods before and after irradiation. The C-V and G omega-V measurements were carried out at 1 MHz. The density of interface states (N-ss) as a function of E-c-E-ss was obtained from the forward bias I-V data by taking into account the bias dependence effective barrier height (Phi(e)) and series resistance (R-s) of device at room temperature. Experimental results show that the values of ideality factor (n), R-s and N-ss increased after gamma irradiation. It was found to degrade the reverse leakage current with radiation whereas its effect on the forward I-V characteristics was negligible. The results show that main effect of the radiation is the generation of N-ss with energy level within the forbidden band gap of Si between polymer and semiconductor. In addition, the values of R-s were determined from Cheung's method, and it was seen that these values increased with radiation effect. As seen I-V and C-V characteristics, the main electrical parameters such as ideality factor (n), R-s, N-ss were strongly influenced with the presence of radiation. (C) 2010 Wiley Periodicals, Inc. J Appl Polym Sci 118: 596-603, 2010