Experimental and Numerical Analyses of Crystallization Processes of In_xGa_1-xSb under Different Gravity Conditions

Abstract

Microgravity studies on the dissolution and crystallization of InGaSb were done with a sandwich combination of InSb and GaSb {111} as the starting material using a Chinese recoverable satellite in 1996. The same experiments were performed under normal gravity condition for comparison. The shape of the solid/liquid interface and compositional profiles in the solution were found to be significantly affected by gravity. To study the effect of gravity on the solid/liquid interface and composition profiles, a numerical simulation has been done. Melting and crystallization experiments of InGaSb were done under the reduced gravity condition (10^-2G) in an airplane and at the normal gravity condition (1G) in the laboratory. Crystallized InGaSb was found to contain many needle crystals in both the cases. However, in the case of the sample prepared at the reduced gravity condition, there was more number of large sized crystals than in the sample prepared under normal gravity. Reduced gravity condition was found to be more conducive for crystal growth than the normal gravity condition. Formation of spherical projections on the surface of InGaSb during its crystallization was in-situ observed using a high speed CCD camera in the drop experiment. Spherical projections showed dependence of gravity during its growth. Indium compositions in the spherical projections were found to vary depending on the temperature.