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)

A broad band with a fine structure on the higher energy side has been commonly observed in photoluminescence at 4.2 K from compensated Si for solar cells involving P donors and B acceptors on the order of 10 16 cm À3. We calculated the theoretical spectrum of donorÀacceptor (DA) pair luminescence from the density distribution of pairs as a function of the transition energy of respective pairs with separations ranging from 1.9 to 3.3 nm. A close agreement was obtained between the observed spectral structure and the theoretical curve using the generally accepted P donor and B acceptor ionization energies, where a systematic deviation was explained by the Van der Waals interaction between shallow P donors and B acceptors. This allows us to conclude that the band with the fine structure is due to the P-donorÀB-acceptor pair recombination. This identification was confirmed by the observation of As-donorÀB-acceptor pair luminescence in an As-doped sample. The present findings indicate that P and B impurities with concentrations on the order of 10 16 cm À3 are unlikely to form complexes and that their ionization energies are not changed from those in the low concentration range. V

A fine structure on the higher energy side of donor-acceptor (DA) pair luminescence at 4.2 K has been analyzed in compensated Si involving P donors and B acceptors. We calculated the density distribution of DA pairs against photon energy from the number of pairs as a function of the transition energy of respective pairs. A close agreement was obtained between the density curve and the observed spectral structure using the generally accepted values of energy gap and P donor and B acceptor ionization energies. This allows us to conclude that the structure is due to discrete DA pair recombination.