The morphological, optical and electrical properties of undoped Zinc Oxide (ZnO) and 0.5% and 2% Ag-doped ZnO based Photodiodes were investigated. ZnO samples, which were deposited on p-type Si semiconductor substrates using spin a coating method, were produced by sol-gel method. The morphological properties of the ZnO films were investigated by atomic force microscopy. The results revealed that thin films are in nanofiber like structure that nanofiber spread homogeneously on the substrate. Additionally, the permittivity, absorbance, reflectivity and bandgap energy values were calculated by using the UV measurement results. The optic bandgaps of the films were also calculated by the optical absorption method. Each sample shows permittivity properties in the visible region; samples show absorption properties in the region where the applied wavelength is smaller than 400 nm. Reflecting boundaries were shift to higher boundaries with increased dopant effect. The transmittance of samples was found low in the UV region, but it shows higher characteristics which are between 78 and 88% in the visible region. To investigate the electrical properties of produced thin films, Current-Voltage, Capacitance-Voltage, Conductance-Voltage characteristics and Current-Time measurements were obtained in different illumination intensities. It was seen that the samples show photoconductive performance.