Vacuum Metallurgical Purification Of High Alumina Doped Monocrystalline Silicon Tailings

Nowadays, most of manufacturers and research organizations for polycrystalline silicon production around the world are thinking about the low-cost manufacture procedure into their consideration. It is highly regarded in a wide range that, to obtain solar grade polycrystalline silicon by using metallurgical method to purify the remnants of mono-crystalline silicon production.To gain high-purity polycrystalline silicon from mono-crystalline silicon tailing material, one strategy based on vacuum directional solidification technique is used to purify tailing material of Al-doped P-type mono-crystal silicon. ICP-AES (Inductively coupled plasma-atomic emission spectrophotometry) analysis is used to detect the concentration of aluminum. The analysis results indicate that the concentration of aluminum increases along the longitudinal direction from bottom to the top of ingot, and the impurities are remarkably eliminated. Optical metallographic microscope patterns, XRD (X-ray diffraction) and EBSD (Electron Back Scattering Diffraction) statistic diagrams illustrate the behaviors of crystal growth during the purification processes. And microstructure of polycrystalline silicon is also a very importance research point.