METHOD FOR MAINTAINING CONTAINED VOLUME OF MOLTEN MATERIAL FROM WHICH MATERIAL IS DEPLETED AND REPLENISHED

.A main crucible (11) of molten semiconductor (13) is replenished from a supply crucible (111; 711) maintained such that there are always two phases of solid (103) and liquid (113) semiconductor within the supply crucible (111; 711). Heat added to melt the solid material results in the solid material changing phase to liquid, but will not result in any significant elevation in temperature of the liquid within the supply crucible (111; 711). The temperature excursions are advantageously small, being less than that which would cause problems with the formed product. The solid product material (103) acts as a sort of temperature buffer, to maintain the supply liquid temperature automatically and passively at or very near to the phase transition temperature. For silicon, excursions are kept to less than 90?C, and even as small as 50?C. The methods also are useful with germanium. Prior art silicon methods that entirely melt the semiconductor experience excursions exceeding 100?C.