Interdisziplinäres Zentrum für Materialwissenschaften
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Interdisziplinäres Zentrum für Materialwissenschaften
Nanotechnikum Weinberg
Heinrich-Damerow-Str. 4,
D-06120 Halle, Germany
Phone: +49 345 55 28471
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H. S. Leipner, R. F. Scholz, F. Syrowatka, J. Schreiber, P. Werner
Copper diffusion in dislocation-rich gallium arsenide
Phil. Mag. A 79,11 (1999), 2785-2802

The interaction of copper with dislocations was studied in silicon-doped gallium arsenide by means of cathodoluminescence and transmission electron microscopy. Depending on diffusion temperature and cooling rate, several structures of defect complexes or microdefects surrounding the dislocations were found. The results could be explained by considering the local non-equilibrium of intrinsic point de-fects induced by Cu in- and out-diffusion. The kick-out mechanism was established as the responsible diffusion mechanism. The change in the solubility and the shift of the Fermi level must be taken into account in order to understand the defect formation. The generated defect distributions gave rise to bright or dark contrasts at dislocations in cathodoluminescence images. A Cottrell atmosphere of dissolved copper is not sufficient to explain this behaviour. The formation of extended defects like precipitates and small dislocation loops in the strain field of dislocations is the reason for the change of the material properties over a distance of several micrometres from the dislocation. A metastable phase of orthorhombic Cu5 As2 was found in the precipitates at dislocations by energy-dispersive X-ray analysis and high-resolution transmission electron microscopy.

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