Structural change by annealing process at σ9 grain boundaries in multicrystalline silicon substrate for solar cells

摘要

σ9 grain boundaries (σ9 GBs) in the multicrystalline silicon substrates with and without annealing process were characterized by micro X-ray fluorescence, transmission electron microscopy (TEM) observation, and UV-Raman spectroscopy mapping. The Ni aggregations appeared at some σ9 GBs only after annealing. The differences in the characteristics of GBs with and without annealing were evaluated. Clear structure changes were observed by TEM evaluation for the corresponding σ9 GBs after annealing. At the same σ9 GBs, the stress concentration was observed without an annealing process and disappeared with one. We consider that the Ni aggregation was enhanced by stress accumulation and silicide accelerated the atomic rearrangement at the σ9 GBs.