Synchrotron-based impurity mapping

Studies were performed on metal impurity precipitates in silicon using synchrotron-based X-rays. The elemental distribution and chemical state of metal impurities were measured by using synchrotron-based X-ray fluorescence (mu-XRF) and X-ray absorption spectroscopy (mu-XAS), both with a 1-2 mu m(2) spatial resolution. With these systems we have identified preferred precipitation sites for metal impurities in silicon and we have correlated poor solar cell performance with metal impurity distributions. Furthermore, we have studied the dissolution rate of metal precipitates as a function of thermal treatment and we have analyzed the chemical state of metal precipitates in silicon. Discussions of metal precipitate stability are presented in regards to the chemical state and material improvement. (C) 2000 Elsevier Science B.V. All rights reserved.