Quantitative analysis of impurities in solar-grade Si by photoluminescence spectroscopy around 20 K

We report details about the quantitative analysis of B and P impurities in the concentration range between 1 × 10¹⁴ and 1 × 10¹⁷ cm^–3 by photoluminescence (PL) in solar-grade Si (SOG-Si). The intensity ratio of impurity-bound exciton (BE) to free exciton (FE) at 4.2 K was used as a measure of the impurity concentration in the range between 5 × 10¹⁰ and 1 × 10¹⁵ cm^–3 in the standard PL method. We raised the sample temperature to enhance the FE emission, which enabled us to extend the concentration range higher. The sample temperature was accurately determined from the FE-line shape. We deduced a formula for the determination of the B and P concentrations in the higher range from the BE/FE ratio and the sample temperature (© 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)