ON THE DETERMINATION OF THE NATURE OF DEFECT CLUSTERS PRODUCED BY DISPLACEMENT CASCADES .2. APPLICATION OF STEREO IMAGING TECHNIQUES TO HEAVY-ION DAMAGE IN COPPER

The black-white (B-W) stereo technique has been critically assessed an d applied to the determination of the nature of small point-defect clu sters in copper produced by Kr+ heavy-ion irradiation at room temperat ure. Several precautions were introduced in an attempt to improve the reliability of the analysis. It was found that most defects lying in t he first approximately 10 nm of the foil are vacancy in nature, togeth er with some of the deeper clusters. There was no unequivocal evidence for interstitial clusters. Some were more likely to be interstitial t han vacancy on the criteria chosen, although the evidence is weak. Def ects sometimes showed inconsistent contrast from one imaging condition to another, demonstrating the difficulty of placing them in the layer structure with complete confidence. The near impossibility of establi shing that interstitial clusters are not present is shown by the fact that over half (53%) the total number of clusters could not be analyse d because they did not show clear B-W contrast in a minimum number of imaging conditions. Various correlations are made between parameters s uch as defect sizes with the depths of the defects in the foil.