In this work, the Metal-organic Chemical Vapor Deposition (MOCVD) technology was used to successfully grow Si-doped β-Ga2O3 films on C-plane sapphire substrates. The effects of Si flow rate on the surface morphology, crystal composition, electrical and optical properties of the films were characterized and analyzed. The experimental results show that the full width at half maximum (FWHM) and root mean square (RMS) of the films are improved with the decrease of Si flow rate. More importantly, only the sample with the lowest Si flow rate showed conductive ability, and its carrier concentration and mobility were 4.20 cm2/V·s and 3.33 × 1016 cm−3, respectively. In addition, we also made photodetectors corresponding to the thin films. The test results showed that the external quantum efficiency (EQE) and responsiveness (R) of the detectors improved with the decrease of Si flow rate.