The effect of annealing ambient on carrier recombination in boron implanted silicon

The selection of either an oxidising or inert ambient during high temperature annealing is shown to affect dopant activation and electron-hole recombination in boron implanted silicon samples. Samples implanted with B at fluence between 3 × 10¹⁴ cm^-2 to 3 × 10¹⁵ cm^-2 are shown to have lower dopant activation after oxidation at 1000 °C compared to an equivalent anneal in an inert ambient. In addition, emitter recombination is shown to be up to 15 times higher after oxidation compared with an inert anneal for samples with equivalent passivation from deposited Al₂O₃ films. The observed increase in recombination for oxidised samples is attributed to the enhanced formation of boron-interstitial defect clusters and dislocation loops under oxidising conditions. It is also shown that an inert anneal for 10 minutes at 1000 °C prior to oxidation has no significant impact on sheet resistance or recombination compared with a standard oxidation process. J_0p+ as a function of sheet resistance for Al₂O₃ passivated samples after 1000 °C anneal for 70 minutes.