This thesis focused on fabrication and characterization of CVD grown p-type graphene and n-type Si Schottky junction photodiode with rectification behavior. The device operated at wavelength range between 390 and 1100 nm at self-powered mode. The device was encapsulated with Epoxy Resin to prevent graphene from atmospheric adsorbates. The electronic and optoelectronic characterizations of the devices were done before and after coating the devices with ER. By encapsulation stability of the device was enhanced in terms of photoresponsivity. The maximum obtained photoresponsivity value of the bare device was 0.56 A/W. Also, time-resolved photocurrent spectroscopy measurements showed that the devices exhibited enhanced photodetector performance in terms of photo-switching characteristics. Furthermore, electrical characteristics of Gr/n-Si Schottky photodiode under various illumination power densities with 850 nm wavelength were investigated. The short circuit current showed linear response to power density. However, open circuit voltage exhibited two phased slow and fast increment with increased power density. Hall effect measurements were conducted in order to investigate hole carrier concentration and mobility of the graphene on n-Si. With increasing the power density the carrier concentration increased and the mobility decreased. Besides, light induced manipulation of the Schottky barrier height of Gr/n-Si photodiode was studied. Schottky barrier height of the graphene measured by KPFM method as 0.4 eV. With increasing power density we found that Schottky barrier height of the device increased from 0.4 eV to 0.5 eV and showed similar trend with the change in open circuit voltage.