The fabrication of Zn-doped amorphous GaN (a-GaN : Zn) films deposited on glass substrates is reported. The role of Zn in a-GaN films is also discussed with respect to light emission. A bluish photoluminescence peak at around 450 nm was observed from the a-GaN : Zn films at room temperature, which was not observed from the undoped a-GaN films. The emission intensity of a-GaN films was higher than that of undoped a-GaN films. This is due to the improvement of networks in amorphous films upon the introduction of Zn doping. The Zn doping of a-GaN films is effective for the fabrication of high-luminescent a-GaN films with a strong blue-light emission.