Deep level transient spectroscopy was used to measure the electrical activity of deep levels in n+p junctions applied in solar cells based on Si. Due to the asymmetry of the diode structures the investigation was focused on defects present in p-type Si. The presence of several levels was reported. While interpreting the data, it was noticed that some of the revealed traps involve metallic impurities, simultaneously showing properties characteristic for extended defects. Based upon both these facts, it was suggested that extended defects were probably generated during device processing and controlled the electrical activity, which depends on the degree of metal contamination of the Si material.

Electrical Activity of Deep Traps in p-Type Si. M.Kaniewska, M.Lal: Solar Energy Materials and Solar Cells, 2002, 72[1-4], 509-15