External gettering of silicon materials containing various efficiency-limiting defects

Several external gettering processes were applied to various as‐grown and intentionally contaminated silicon materials in order to better understand the interaction of metallic impurities with structural defects contained in the materials. These materials included float zone silicon, different types of solar grade CZ materials, and two types of polycrystalline silicon; cast ingot and ribbon. This diverse group of materials were subjected to POCl3, spin on glass phosphorous, aluminum and spin on glass phosphorous/aluminum co‐gettering treatments. Some samples were also intentionally contaminated with Fe to 1.4×1014 atom/cm3, and then gettered. A preferential etch was then applied to selected samples in order to observed the structural defects. The polycrystalline materials, which exhibited regions of high and very low dislocation densities, responded best to aluminum gettering and recovered well after Fe contamination and gettering. Single crystal materials, except those containing high concentrations of c...