Terbium (Tb3+) doped zinc oxide (ZnO) or (ZnO:Tb3+) thin films were grown on silicon substrates by the pulsed laser deposition technique at different growth temperatures that were varied from room temperature (RT) to 400°C. The effects of substrate temperature on the structural and optical properties of the ZnO:Tb3+ films were investigated by X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy and RT photoluminescence spectroscopy. The band to band and deep level defect emissions were observed for all substrate temperatures. The silicon that has diffused from the substrate has occupied the position of the Zn vacancies in the ZnO:Tb3+ thin films at the higher substrate temperatures (400°C). A blue emission was observed for all the ZnO:Tb3+ thin films deposited at the different substrate temperatures.