SOME NEW DESIGN-FEATURES FOR VERTICAL BRIDGMAN FURNACES AND THE INVESTIGATION OF SMALL-ANGLE GRAIN-BOUNDARIES DEVELOPED DURING VB GROWTH OFGAAS

We discuss two vertical Bridgman concepts which exhibit some new desig n features. The first one is aimed at creating a mainly axial heat-flo w during the growth process. The concept of the second one follows tha t of a classical Stockbarger arrangement with an auxiliary heater in t he gradient zone. Both concepts should help to achieve flat and slight ly convex growth fronts to allow examination of the influence of the p hase boundary on single crystal yield and the quality of the crystals. As losses are discussed as a possible cause of nucleation of polycrys talline growth, when the VB technique is employed without As sources.