Experimental study of the solid-liquid interface dynamics and chemical segregation in concentrated semiconductor alloy Bridgman growth

Three Ga1−xInxSb samples with compositions x=0.04, 0.1 and 0.2 have been solidified by the vertical Bridgman method. The position and shape of the solid-liquid interface has been marked by electrical pulses all along the growth and revealed by subsequent metallography. The axial and radial segregation of the In has been measured by chemical analysis of the solid. The results show that the effect of the chemical segregation, coupled to thermosolutal convection, leads to huge deformations of the solid-liquid interface, with interface curvature even larger than the sample diameter. A sharp increase of the chemical composition is simultaneously observed in the most concentrated samples and interface destabilization occurs quickly. Interpretation of these results involves a strong coupling of the thermal, hydrodynamical and chemical fields.