Identification of intrinsic gettering centers in oxygen-free silicon crystals

Abstract
Intrinsic gettering centers in oxygen-free silicon crystals after a high–low–medium-temperature annealing cycle were successfully identified using transmission electron microscopy and energy dispersive x-ray spectroscopy. These centers have a butterfly-type shape and they consist of interstitial-type extended multiple dislocation loops in {110} planes of 0.1–0.7 μm diameter and a high density of small 3–15-nm-diam precipitates located inside the dislocation loops and/or on the dislocation line. Compositional x-ray analysis identified Cu as the predominant metal component of the precipitates. Occasionally Ni and very rarely Fe were also detected.