In our work, graphene oxide (GO) doped nickel oxide (NiO) nanocomposite was used an interfacial layer to investigate electrical and photovoltaic properties of the Ag/p-Si metal semiconductor structures. GO doped NiO nanocomposite films were prepared by Hummers method. This nanocomposite films were characterized by EDX and SEM analyses. The electrical and photovoltaic characteristics of the Ag/GO-doped NiO/p-Si heterojunction were investigated using current-voltage (I-V) and capacitance-voltage (C-V) measurements under dark and 30 mW/cm(2) light illuminations conditions at room temperature. The values of ideality factor, reverse saturation current, and barrier height were obtained as 4.52, 1.66 x 10(-10) A, and 0.903 eV; 4.38, 3.12 x 10(-10) A and 0.887 eV in dark and under light illumination, respectively. At the same time, the interface state densities as a function of energy distributions was extracted from the forward-bias IeV measurements. Experimental investigations show an increase in a reverse current in photodiodes with increasing the illumination intensity. (C) 2017 Elsevier B.V. All rights reserved.