The Cu photoluminescence defect and the early stages of Cu precipitation in Si

This theoretical–experimental study focuses on the formation of the substitutional-tri-interstitial cluster Cus1Cui3, which has been proposed as the photoluminescence defect CuPL. The configurations and electronic properties of the intermediate defects Cus1Cui1 and Cus1Cui2 are calculated, and their electrically active levels are obtained from conventional and Laplace deep-level transient spectroscopy. The vacancy formation energy near copper-related defects is calculated and found to be much smaller than in the perfect crystal. Then, we show how Cus1Cui3 could become the seed of agglomerates of Cus1Cui3 “units.” The discussion focuses mostly on unanswered questions about the discrepancies between the calculated and measured properties of CuPL and Cus1Cui3.