Tb 3 + doped Zn 2 SiO 4 films have been deposited on SiO 2 buffered Si wafers by sol-gel method. The structures of these films have been investigated with X-ray diffraction (XRD), atomic force microscopy (AFM), and scanning electron microscopy (SEM). The results revealed that these films were composed of nanometer-size grains with a Willemite structure and had smooth surfaces. Photoluminescence measurements of the films showed a strong emission from 5 D 4 to 7 F 5 at 544 nm. The blue emission from 5 D 3 - 7 F j was depressed because of cross-relaxation effect. The decay kinetics of the 5 D 4 - 7 F 5 green emission was studied and a best fitting was obtained by a double exponential function. The lifetime of the excited 5 D 4 state is estimated to be 5.2 ms.