Temperature behaviour of photoluminescence and electron-beam-induced current recombination behaviour of extended defects in solar grade silicon

The temperature dependence of D-band and band-to-band (BB) luminescence was measured in EFG samples between 80 K and room temperature for defects/dislocations presenting different amounts of contamination. The contamination density was estimated from the temperature behaviour of the electron-beam-induced current contrast, ranging between about 10(4) and 10(6) impurities cm(-1) dislocation length. The D1 line became already visible at room temperature but its intensity was found to exhibit a maximum at about 150 K. D2, D3 and D4 start to show up at about 250, 190, and 170 K, respectively, and increase their intensities upon lowering temperature. At room temperature the width of the D1 line is broad and becomes narrower upon lowering the temperature. D2 shows the opposite behaviour. The intensities of D1 and D2 were observed to show strong variations across the sample, whereas this was not observed for the pair D4/D3. In particular, the origin of the lines D1 and D2 is still far from being understood. Two more lines at 1.040 and 0.987 eV were found in regions where the BB recombination is strong. They appear without any defect contribution and are explained as phonon replicas of the band edge luminescence.