Influence of Temperature of Silicon Dioxide Powder Annealing on the Aluminum-Induced Crystallization of Polycrystalline Silicon

The phase composition, structure, and size of particles and agglomerates formed by annealing of the powder obtained from hydrophobizing organosilicon liquid in the presence of aluminum powder (5–10 wt %) were studied by X-ray diffraction, Fourier IR spectroscopy, and laser granulometry. The annealing temperature varied from 550 to 700°С influences the mean size of the individual particles, and the aluminum content influences the agglomerate size. An increase in the heat treatment temperature leads to a decrease in the mean diameter of separate particles. The samples containing 10% aluminum powder have the largest agglomerate size. In turn, the formation of the polycrystalline silicon phase from the amorphous silica-containing powder system in the temperature range of solid-phase reactions depends on the particle and agglomerate size. To obtain polycrystalline silicon from samples containing coarser agglomerates, it is necessary to raise the annealing temperature at equal process time. The minimal annealing temperature for the start of the polycrystalline silicon formation was 550°С, and the required amount of aluminum powder was 5%.