The formation of device-grade polycrystalline silicon (poly-Si) films on low-cost substrates at low temperature using simple and fast processes is of enormous interest for photovoltaics and lar ge-area electronics. In this paper we report the realisation of thick (similar to 5 mum), large-grained (similar to 5 mum), uniform poly-Si films on glass at a substrate temperature below 650 degreesC. This important technological progress was achieved by using ion-assisted deposition of silicon for thickening a thin poly-Si seeding layer grown on glass by aluminium-induced crystallisation of amorphous silicon.