MODELING OF ELLIPSOID MIRROR FURNACE FOR FLOATING-ZONE CRYSTAL-GROWTH

Because of its compactness and high efficiency, the image furnace usin g ellipsoid mirrors to focus infrared heating from lamps has widely be en used in floating-zone (FZ) crystal growth. However, little research has been reported on modeling energy distribution in such a system. I n this paper, a simple model considering direct and indirect radiation from the lamps is presented. This model is consistent with the point- source model as the lamp size is diminished. The effects of lamp size, shape, orientation, and defocusing are discussed. The model is furthe r integrated with a three-dimensional thermal-capillary model. Therefo re, the temperature distribution and the zone shape of the sample duri ng FZ growth in the furnace can be estimated. Temperature measurements of a graphite rod in a mirror furnace were also conducted to validate the global model.