Liquid‐Tin‐Assisted Molten Salt Electrodeposition of Photoresponsive n‐Type Silicon Films

Production of silicon film directly by electrodeposition from molten salt would have utility in the manufacturing of photovoltaic and optoelectronic devices owing to the simplicity of the process and the attendant low capital and operating costs. Here, dense and uniform polycrystalline silicon films (thickness up to 60 µm) are electrodeposited on graphite sheet substrates at 650 °C from molten KCl–KF‐1 mol% K2SiF6 salt containing 0.020–0.035 wt% tin. The growth of such high‐quality tin‐doped silicon films is attributable to the mediation effect of tin in the molten salt electrolyte. A four‐step mechanism is proposed for the generation of the films: nucleation, island formation, island aggregation, and film formation. The electrodeposited tin‐doped silicon film exhibits n‐type semiconductor behavior. In liquid junction photoelectrochemical measurement, this material generates a photocurrent about 38–44% that of a commercial n‐type Si wafer. Dense and uniform polycrystalline silicon films (thickness up to 60 µm) were successfully electrodeposited on graphite from molten KCl‐KF‐1 mol% K2SiF6 containing a tiny amount of tin which promotes the growth of n‐type material. In the photoelectrochemical measurement this tin‐doped Si film generates a photocurrent about 38–44% that of a commercial n‐type Si wafer.