Monodisperse 8 nm Fe3O4 nanoparticles (NPs) were synthesized by the thermal decomposition of iron(III) acetylacetonate in oleylamine and then were deposited onto n-type silicon wafer having the Al ohmic contact. Next, the morphology of the Fe3O4 NPs were characterized by using TEM and XRD. The optical properties of Fe3O4 NPs film was studied by UV-Vis spectroscopoy and its band gap was calculated to be 2.16 eV. Au circle contacts with 7.85 x 10(-3) cm(2) area were provided on the Fe3O4 film via evaporation at 10(-5) Torr and the Au/Fe3O4 NPs/n-Si/Al heterojunction device were fabricated. The temperature dependent junction parameters of Au/Fe3O4/n-Si/Al device including ideality factor, barrier height and series resistance were calculated by using the I-V characteristics in a wide temperature range of 40-300 K. The results revealed that the ideality factor and series resistance increased by the decreasing temperature while the barrier height decreases. The Richardson constant of AufFe(3)O(4)/n-Si/Al device was calculated to be 2.17 A/K-2 cm(2) from the I-V characteristics. The temperature dependence of Au/Fe3O4/n-Si/Al heterojunction device showed a double Gaussian distribution, which is caused by the inhomogeneities characteristics of Fe3O4/n-Si heterojunction. (C) 2016 Elsevier Inc. All rights reserved.