In this study, poly (linoleic acid)-g-poly(methyl methacrylate) (PLiMMA) graft copolymer is used as an interfacial layer in a Schottky diode for the first time. Au/poly (linoleic acid)-g-poly(methyl methacrylate) (PLiMMA)/n-Si diode was fabricated and main electrical characteristics of the diode were investigated using I-V measurements in dark and under illumination at room temperature. Ideality factor (n), barrier height (Phi(B0)) and serial resistance (R-s) values of the diode were found as 2.8, 0.87 eV and 8096 Omega for dark, and 6.3, 0.71 eV and 676 Omega for 100 mW/cm(2) illumination intensity. Also, the reasons of deviation from ideal thermionic emission theory were investigated using Cheung&Cheung method and Card&Rhoderick's function which are used for calculating voltage dependence of barrier height (Phi(B)(V)), series resistance (R-s) and number of surface states (N-ss) of the Au/PLiMMA/n-Si diode. (C) 2014 Elsevier B.V. All rights reserved.