Imaging of chromium point defects in p-type silicon

In this work a method for the spatially resolved detection of the Cr point defect distribution in p-type silicon based on photoluminescence imaging was developed and successfully applied on monocrystalline and multicrystalline wafers. Chromium was identified by its metastable defect configuration and the association time during the formation of chromium-boron pairs. Further defects which could influence the Cr concentration determination have been studied and their influence was suppressed. For a quantitative evaluation of the chromium concentration, the knowledge of exact values of defect parameters such as energy level and capture cross sections for electrons and holes for both Cr states is essential. From the doping dependence of the lifetime, published defect parameters have been analyzed and adjusted slightly in order to explain experimental results. With these parameters reasonable averaged Cr point defect concentrations have been determined for different monocrystalline and multicrystalline samples. Furthermore, space-resolved images of the Cr point defect concentration could be acquired, permitting study of the distribution within a multicrystalline sample with respect to grains and grain boundaries or dislocation clusters.