Polycrystalline ZnO thin film was obtained on the p-Si for the heterojunction diode fabrication by sol-gel method. X-ray diffraction study showed that the texture of the film is hexagonal with a strong (002) preferred direction. Scanning electron microscope image of ZnO showed that the obtained ZnO thin films had more porous character. High purity vacuum evaporated silver (Ag) and aluminum (Al) metals were used to make Ohmic contacts to the n-ZnO/p-Si heterojunction structure. The electrical properties of Ag/n-ZnO/p-Si/Al diode were investigated by using current-voltage measurements. Ag/n-ZnO/p-Si/Al heterojunction diode showed a rectification behavior, and its ideality factor and barrier height values were found to be 2.03 and 0.71 eV by applying a thermionic emission theory, respectively. The values of series resistance from dV/d (lnI) versus I and H(I) versus I curves were found to be 42.1 and 198.3 Omega, respectively. (C) 2012 Elsevier B.V. All rights reserved.