Gallium arsenide
The Crystal Growth Furnace (CGF) is a reusable facility for investigating crystal growth in microgravity. It is capable of automatically processing up to six large samples at temperatures up to 1,600 degrees Celsius. Additional samples can be processed upon performing manual sample exchange. Two methods of crystal growth, directional solidification and vapor transport, were used on USML-1. By analyzing the composition and the atomic structure of crystals grown without the dominating influence of gravity, scientists will gain insight into correlations between fluid flows during solidification and the defects in a crystal. CGF operated for 286 hours and processed seven samples, three more than scheduled, including two gallium arsenide semiconductor crystals. Gallium arsenide crystals are used in high-speed digital integrated circuits, optoelectronic integrated circuits, and solid state lasers. Crew members were able to exchange samples, using a specially designed flexible Glovebox, to provide the additional experiment operations.