Regensburg 1998 – wissenschaftliches Programm

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DS: Dünne Schichten

DS 5: Ionenimplantation III

DS 5.4: Fachvortrag

Montag, 23. März 1998, 17:15–17:30, H 31

Ion Implantation in TiO₂: Effect of the Oxidation State on the Lattice Site Occupation — •R. Fromknecht¹, O. Meyer¹, I. Khubeis², and S. Massing¹ — ¹Forschungszentrum Karlsruhe, INFP, Postfach 3640, D-76021 Karlsruhe — ²Department of Physics, University of Jordan, Amman, Jordan

Ions with different oxidation states Hg(2), Sn(4), Sb(5), and Pb(4) were implanted in TiO₂ (rutile) and their lattice site location was determined using Rutherford backscattering and channeling (RBS-C). The maximum solubility concentrations on Ti sites were about 5·10¹³/cm² for Hg, 1·10¹⁵/cm² for Sb and greater than 3·10¹⁵/cm² for Sn. For Pb a value of 5·10¹³/cm² was observed, although Pb should be insoluble as estimated from the solid solubility rules. The results cannot be explained by the size mismatch energy, as in the case of metals but seems to depend on the oxidation state. The non-substitutional fractions were larger for Hg and Sb, having a net charge on Ti sites. This behaviour is attributed to the formation of impurity-defect complexes, where it is electrostatically favourable for different defects to associate for charge compensation. Supersaturation is reached for Pb, where charge compensation is not required.