Abstract
As the bubble technology has progressed from the research stage into pilot plant operation, the need for larger diameter substrates has developed. Today, typical 3 in. diameter crystals of GGG weigh between 9000 and 10 000 grams and are grown from charges of 12 000 grams or more. The growth of 3 in. diameter GGG crystals with low defect densities 1(?/cm2) presents several problems which are not encountered during the growth of small diameter crystals. The first problem encountered is one of proper scaling of the growth furnace and growth parameters. The second problem is that of melt composition to insure a uniform lattice parameter throughout the entire crystal. A third area which can present problems is the size and mass of the charge required for 3 in. diameter crystals. Each of the parameters and their relationship to crystal imperfections is discussed.