Defect diagnostics using scanning photoluminescence in multicrystalline silicon

Scanning room-temperature photoluminescence (PL) spectroscopy was applied to multicrystalline silicon (mc-Si) wafers to assess electronic properties of the high-quality solar grade material. The intensity of band-to-band emission with the maximum at 1.09 eV measured across entire me-Si wafer positively correlates with minority carrier lifetime measured concurrently using laser-microwave reflection technique. We have found in me-Si wafers an intense "defect" PL band with the maximum at about 0.8 eV and half-width of similar to 75 meV at room temperature. It is strongly localized in "bad" areas possessing a reduced by a factor of two orders band-to-band PL intensity and a noticeable degraded lifetime. High-resolution PL mapping of the 0.8 eV band revealed a link to areas with high dislocation density. PL spectra down to 4.2 K were measured in regions with high and low "defect" band intensity demonstrating a correlation of the 0.8 eV band with distribution of the D3/D4 dislocation lines, The origin of the 0.8 eV band is discussed in a connection with dislocation network. (C) 1999 Elsevier Science B.V. All rights reserved.