Solution grown polysilicon for flat panel displays

Thin-film poly-Si on low-cost substrates is useful for thin-film transistors in flat panel displays or for photovoltaics. The films reported herein were formed at 600 °C by d.c. magnetron sputtering from a Si-target onto a SiO₂/Mo substrate, pre-coated with Sn or In/Ti to give a liquid phase growth. Poly-Si films have given a preferred (111) orientation, grain size up to 20 μm, a carrier mobility exceeding 100 cm²/Vs and carrier lifetime of 8 μs when using the Sn pre-layer. The Sn pre-layer typically gave smaller grain size than did the In/Ti solvent but the latter gave lower carrier lifetime from Ti incorporation in the film. The film from the Sn pre-layer gave carrier mobility of 140 cm²/V-s after hydrogenation by microwave electron cyclotron resonance. Properties of the Si thin-film can be controlled by type of pre-layer, doping of the target, substrate temperature and deposition environment.