Nanocrystalline silicon thin films were successfully prepared via a magnesiothermic reduction process. The initial magnesium content was restricted by the thickness of the film deposited on a quartz glass substrate by magnetron sputtering. After the magnesiothermic reduction process, the Raman spectroscopy results revealed a strong correlation between the thickness of the nanocrystalline thin films and the initial magnesium content. The thickness of the nanocrystalline thin films first increased to a maximum and then decreased as the initial magnesium content was further increased. Based on the solid-state reaction between Mg and SiO2, the mechanism behind this phenomenon is explained. In addition, the Raman spectroscopy results showed that the average grain size was almost constant and the crystalline volume fraction was found to be proportional to the silicon content. The band gap of the nanocrystalline silicon thin film was estimated to be 2.94 eV.
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