The influence of light absorption on Cu related defect reactions in p-type Si was investigated by transient ion drift measurements. It was found that Cu out-diffusion and formation of Cu complexes were two competitive processes whose relative importance depends on light intensity. At low intensities, a reduced surface potential allows complete Cu out-diffusion. Above a certain threshold value, however, Cu complexes were formed which could be responsible for the earlier reported optically activated recombination activity of Cu in Si. It was shown that the observed Fermi-level dependence of the defect formation rate cannot be explained in terms of an optically induced change in the interstitial Cu charge state. The high thermal stability of the formed Cu complexes further points out that the formation of electrostatically bound Cu-defect pairs may be ruled out.

Influence of Light on Interstitial Copper in p-Type Silicon. A.Belayachi, T.Heiser, J.P.Schunck, A.Kempf: Applied Physics A, 2005, 80[2], 201-4