Effects of Solar Cell Processing Steps on Dislocation Luminescence in Multicrystalline Silicon

Abstract

We examine the impacts of hydrogenation and phosphorus gettering steps on the deep-level photoluminescence spectra of dislocations and the surrounding regions in multicrystalline silicon wafers, using micro-photoluminescence spectroscopy with micron-scale spatial resolution. We found that the D1 line, originating from secondary defects around dislocation sites, was enhanced significantly after gettering but remained unchanged after hydrogenation, suggesting that the former process reduced the concentration of metal impurities around the dislocations while the latter process did not alter the relevant properties ofdefects and impurities. In addition, the D3 and D4 intensities were found to be unchanged after different processing steps, indicating that the intrinsic structure of the dislocations was not affected by the investigated processes. Finally, we report empirical evidence supporting the hypothesis that D3 is not the phonon replica of D4 due to their different intensity ratio at different locations in the wafers.