Instrumental determination of phosphorus in silicon for photovoltaics by β spectroscopy: a new approach

In this study, we report on the investigation of a beta-gamma-anticoincidence set up for the determination of phosphorus in silicon for photovoltaics by Instrumental Neutron Activation Analysis. For the suppression of disturbing beta/gamma radiation emitted by impurities, a plastic scintillator for beta-detection is surrounded by a well type NaI(Tl) gamma-detector. A suppression of 40 % for the impurities Co-60 and Sb-124 could be achieved. The limit of detection was determined to be less than 0.1 ppm. In order to correct different beta absorption, dedicated Geant4 simulations were used. With first quantitative measurements the phosphorus concentration in silicon could be determined.