FeSi2 is a promising environment-friendly semiconductor material. However it is difficult to obtain pure phase for such a line compound. To investigate the solubilities for a third alloying elements, in this work Fe3Si8M (M=B, Cr, Ni, Co) ternary alloys are designed based on the cluster-plus-glue-atom-model. Thin films are then prepared using magnetron sputtering. The as-deposited films are all amorphous and become crystallized after annealing at 850 for 4 h. It is shown that samples alloyed with third components Cr and B can reach single phase easily. However, the main phase is phase and the films tend to exhibit metallic characteristics while alloyed with Co. Of these films, the Fe2.7Si8.4B0.9 film presents the most prominent semiconductor performance, and it has a resistivity of 0.17 cm, a sheet carrier concentration of 2.81020 cm-3, a mobility of 0.13 cm2=Vs and a band-gap width of 0.65 eV. It is confirmed that doping a proper third component can expand the phase zone, exhibiting a similar semiconductor property to that of binary -FeSi2.