Abstract
A molecular beam epitaxy process was used as a means for doping GaAs layers with rhodium atoms up to 10 19 atoms cm -3. The samples were studied by secondary ion mass spectroscopy, transmission electron microscopy, and photoluminescence spectroscopy. However, the results showed that the Rh atoms were not incorporated in the matrix. No photoluminescence lines which could be related to a ground or an excited state of the “4d” impurity in isolated form was detected. Moreover, a sample which contains an average Rh concentration equal to about 10 19 cm -3, was shown to contain a high density (10 15 cm -3) of small inclusions (≅ 10 nm). The nature, the morphology, and the orientation of these precipitates relative to the matrix were studied. So, it appears that the solubility of the Rh atoms in the GaAs lattice is very low and there is formation of stable RhAs 3 precipitates, which are coherent with the GaAs lattice. As a consequence Rh does not seem to be a good candidate to get semi-insulating GaAs.
Published Version
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