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We investigated macrosegregation of Ge 1 − x Si x mixed crystals over a great variety of compositions. The axial profiles found experimentally are explained by a new one-dimensional boundary layer model, which takes into account the appropriate boundary conditions for Bridgman growth and the non-negligible variation of the segregation coefficient. Comparison of the experimental data with calculations reveals that, in the setup employed here, the melt is close to the limiting case of complete mixing. The diffusion boundary layer thickness is only a few tens of microns. This is in contrast to known experiments, where additional solutal damping of the convection severely affects macrosegregation.

We investigated the Bridgman growth of non-dilute Ge1 − xSix mixed crystals and report on four samples of different composition. They are characterized by metallography and composition analysis. The macroscopic axial concentration profile is close to that of a completely mixed melt. The hydrodynamical origin of this strong stirring is discussed. Fluctuations of growth rate and/or composition result in strong striation patterns. The spacing of the striae is found to be similar for all melt volumes, compositions and thermal environments used in our experiments. The crystal quality is generally poor. All samples show a grain structure. If the seed is of higher Si content than the first part of the growth crystal, formation of grains is considerably reduced. A model for understanding this finding is proposed.

Si x Ge 1- x single crystals with a Ge content up to 20 at% were grown by the Czochralski technique and the growth parameters were defined. The crystalline perfection was evaluated by high resolution X-ray diffractometry (HRXRD). The half widths of the rocking curves were found to be 16–21 arc sec, showing a crystal perfection that lies near commercially available silicon single crystals.

For the Si-Ge solid solution, we were able to identify a polycrystalline wetting layer on the crystal surface. A new model is introduced to explain the appearance of this layer and its influence on crystal quality is discussed.

Transport and photoconductive properties of p-Hg 0.8 Cd 0.2 Te and n-Hg 0.7 Cd 0.3 Te have been studied at temperatures between 16 and 250 K. The crystals showed different lifetimes than that observed in n-type Hg 0.8 Cd 0.2 Te, where Auger recombination was found as the dominating recombination mechanism. The minority carrier lifetime in p-Hg 0.8 Cd 0.2 Te could be explained by Shockley-Read recombination involving a deep donor-like centre located about 6 meV above the valence band edge. In n-type Hg 0.7 Cd 0.3 Te radiative recombination was found to dominate at temperatures above 40 K. Obviously the band gap of this composition is too wide for an effective Auger mechanism. Below 40 K trapping of minority carriers occurs and one observes two life time constants. Here the recombination mechanism was identified as recombination via defects in the band gap.