Study of Structural and Optical Properties of Electrodeposited Silicon Films on Graphite Substrates

Silicon (Si) films were deposited on low-cost graphite substrates by the electrochemical reduction of silicon dioxide nanoparticles (nano-SiO₂) in calcium chloride (CaCl₂), melted at 855 °C. Cyclic voltammetry (CV) was used to analyze the electrochemical reduction mechanism of SiO₂ to form Si deposits on the graphite substrate. X-ray diffraction (XRD) along with Raman and photoluminescence (PL) results show that the crystallinity of the electrodeposited Si-films was improved with an increase of the applied reduction potential during the electrochemical process. Scanning electron microscopy (SEM) reveals that the size, shape, and morphology of the Si-layers can be controlled from Si nanowires to the microcrystalline Si particles by controlling the reduction potentials. In addition, the morphology of the obtained Si-layers seems to be correlated with both the substrate materials and particle size of the feed materials. Thus, the difference in the electron transfer rate at substrate/nano-SiO₂ interface due to different applied reduction potentials along with the dissolution rate of SiO₂ particles during the electrochemical reduction process were found to be crucial in determining the microstructural properties of the Si-films.