ANNEALING METHOD FOR HALIDE CRYSTAL

摘要

Improved outgassing techniques for decreasing oxygen and water concentrations in an annealing furnace, with the result being a significant reduction if not elimination of crystal defects. At the beginning of an annealing process, an airtight chamber of the annealing furnace is evacuated and filled with an inert gas not only one time but multiple times. During the anneal, inert gas, with or without a fluorinating agent, is flowed through the chamber during the heating and cooling steps while the oxygen and water concentrations in the flowing gas are each maintained below 5 ppm and more preferably below 1 ppm.