Distribution of Te in GaSb grown by Bridgman technique under microgravity

Te concentration in GaSb grown under microgravity was measured by spatially resolved photoluminescence (SRPL). For this purpose, a calibration curve i s experimentally obtained to give a relationship between Te concentration a nd PL energy. It was found that after the growth starts the Te concentratio n drops at the melted and unmelted interface and recovers rapidly to the le vel of the initial concentration which means that the distribution is close to that of pure diffusion control. Three possible shapes of the GaSb melt in space were postulated and it is suggested that a wide free surface exist ed on the GaSb melt during growth. The reason for the absence of strong Mar angoni flow is attributed to either the small temperature difference across the free surface or to the presence of a thin oxide film on the melt. (C) 2000 Elsevier Science B.V. All rights reserved.