Growth and evaluation of AgGaS2 and AgGaSe2 for infrared nonlinear applications

The crystal growth technology for the two chalcopyrite compounds AgGaS2 and AgGaSe2 was studied. These two materials demonstrated their promise as important nonlinear crystals for infrared applications ten years ago. However, at the time, a number of various growth related problems such as cracking, twinning and the occurrence of optical scattering centers made it difficult to obtain high quality specimens in sizes exceeding 1 cm. Using seeding and precision-tapered fused quartz growth ampoules, a Bridgman/Stockbarger growth technology was developed to grow crack and twin-free boules in increasingly larger dimensions with an ultimate goal of 4 cm crystals harvested obliquely from c-axis boules. The post-growth heat treatment procedures were studied to understand the solid state chemical reactions and to avoid crystal damage which frequently occurs during these annealing procedures.