Technology and Optical Properties of Amorphous Silicon Grown at Low Temperature by ICPCVD

In this paper, amorphous silicon thin films were grown on glass and sapphire substrates at temperatures of 100℃ and below, using the ICPCVD method. The growth of high-quality amorphous silicon films at low temperatures was achieved by adjusting parameters such as the gas flow ratio of Ar to SiH₄, radio frequency power, and substrate temperature. The effect of substrate temperature on the deposition quality of amorphous silicon films was characterized and analyzed using Raman spectroscopy. It was found that at a substrate temperature of 100°C, the crystalline fraction and microcrystalline size of the amorphous silicon film were 64.4% and 4.7 nm, respectively. In addition, the optical properties such as refractive index and transmittance of the amorphous silicon films were studied, and the calculated optical bandgap of the films was found to be 1.68 eV. Finally, two types of a-Si/SiO₂/a-Si Bragg reflector structures were fabricated with thicknesses of 36/100/41 nm and 62/132/60 nm, respectively. These two structures achieved high reflectivity of 90.4% in the visible light range and 88.9% in the infrared range, respectively.