Selbst- und Fremddiffusion in Siliziumkarbid zur Charakterisierung der atomaren Eigenpunktdefekte in Siliziumkarbid

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The proposal aims at determining properties of native point defects in SiC that are important for diffusion processes in this wide-bandgap semiconductor. For this purpose we will use several radioactive impurity probe atoms that can be implanted at the Bonn isotope separator facility. Suitable probe atoms are 7Be and 35S which combine favourable radioactive decay properties with an expected interstitial-substitutional diffusion mechanism in SiC. This expectation is based on the data found for SiC:Be in the literature and on analogies with the well-characterized features of S in silicon.Concentration-depth profiles will be measured after diffusion annealing over a wide range of temperatures. Detailed numerical analysis of the profiles should lead to the identification of the diffusion mechanism and the transport properties of the vacancies or self-interstitials involved. In favourable cases information about the point-defect charge states and their contribution to self-diffusion in SiC is obtained as well. An ambitious goal is given by the wish to extract point-defect data both for the Si and the C sublattice. We expect that the results of this project will provide a substantial contribution to the present poor understanding of diffusion processes and point-defect behaviour in the technologically important semiconductor SiC.