Microgravity growth of GaSb single crystals by the liquid encapsulated melt zone (LEMZ) technique

A liquid encapsulated melt zone (LEMZ) technique was used to grow [1 0 0] G aSb single crystals under microgravity conditions aboard the STS-77 Shuttle Endeavor mission. One tellurium-doped and two undoped single crystals, enc apsulated in a eutectic mixture of sodium chloride and potassium chloride, were regrown from 16 mm diameter single-crystal rods at translation speeds ranging from 1 to 6 mm/h. The quality of the crystals was compared to those grown on ground using the LEMZ technique at translation speeds ranging fro m 3 to 18 mm/h. It was found that the microgravity-grown crystals, particul arly the Te-doped crystal, exhibited lower dislocation densities than those grown on ground. The dislocation density was also found to depend on the s olid/liquid interface shape with a planar interface resulting in a lower de nsity. Reduction of rotational and nonrotational striations was obtained wi th the encapsulation technique in all crystals. Moreover, the use of the en capsulant allowed for longer and more stable melt zones for those samples p rocessed on ground. (C) 1999 Elsevier Science B.V. All rights reserved.