Microstructure developments and anti-reflection properties of SiO2 films by liquid-phase deposition

In this work, silicon dioxide (SiO2) films were deposited on a multi-crystalline silicon substrate via liquid-phase deposition (LPD) using hydrofluorosilicic acid (H2SiF6) and boric acid (H3BO3) aqueous solution. We controlled the surface morphology and grain structure of the film by using the concentration of H2SiF6, and the particle sizes were controlled by the concentration of H3BO3. Fourier transform infrared spectroscopy showed that three SiOx peaks exist at 1103, 815, and 463 cm−1, respectively. X-ray diffraction revealed a typical broad peak in the range of 14-55° for the SiO2 amorphous particles. The refractive index of the LPD film was 1.41. The reflection of the LPD SiO2 film was affected by the film thickness, and the reflectivity of the film was decreased as the film thickness increased. For the 106 nm SiO2 film thickness, the average reflectance under the measuring conditions was 14.1%. The low reflectance rendered the film a suitable anti-reflection film in multi-crystalline silicon solar cells.