X-ray topographic, lattice parameter and chemical etching studies were made of single crystals which contained 1.2 or 3.0at%Ge. A diffraction contrast in the form of concentric striations was observed in projection topographs and was attributed to a non-uniform distribution of Ge atoms. The etching patterns revealed bands which corresponded to striations and dislocation etch pits. Threading surface dislocations which had a screw Burgers vector component tended to be invisible in some X-ray topographs. A striation-free central crystal region was associated with a crystal lattice that was strongly disturbed by micro-defects; as deduced from topographs. Lattice parameter measurements revealed a non-uniformity of the distribution of Ge atoms across the samples.

Topography and Lattice Parameter of Si:Ge Bulk Crystals. M.Lefeld-Sosnowska, Z.Grygoruk, K.Wokulska, J.Błażewicz: Journal of Physics D, 2001, 34[SA], 144-7