We present the first evident photovoltaic responses from ion-beam synthesized (IBS) polycrystalline p-type beta -FeSi2/n-Si(100) heterojunctions. The triple ion implantation and subsequent annealing at 800 degreesC provided polycrystalline continuous layers similar to 60-nm thick with large crystalline grains of similar to 10 mum The high temperature and long annealing time were very effective in amplifying the photovoltaic responses from the heterojunctions. We achieved a maximum open-circuit voltage of 0.34 V by 5 mW/cm(2) of white light illumination. Furthermore, we confirmed that the annealing procedure at 500 degreesC induced the precipitation of the psuedomorphic metallic gamma phase, which is detrimental to both rectification and the photovoltaic voltage at the p-n heterojunction.