LATTICE SITE OCCUPATION OF IODINE IMPLANTED INTO ALUMINUM

The lattice site occupation of iodine ions implanted into aluminium si ngle crystals at 5 and 293 K was determined by in situ MeV He+ ion cha nneling. After implantation at 5 K the iodine atoms occupy substitutio nal and other regular interstitial positions. Upon annealing to 293 K most of the iodine atoms shift to near-octahedral sites. The relocatio n is attributed to the formation of iodine-hexavacancy configurations. This complex is also formed during implantation at 293 K. The near-oc tahedral fraction at 293 K was measured as a function of iodine concen trations. At concentrations of about 0.003% I in Al [110] the peak hei ght in the center of the channel was about 2.4+/-0.3. Increasing the c oncentration, the peak height decreases to 1.3 at 0.1% I and to 1.0 at 1.5% I.