Vertical Bridgman process

Figure 2. Three spatial scales for modeling melt crystal growth, as exemplified by the vertical Bridgman process. From Theory of Transport Processes in Single Crystal Growth from the Melt, by R. A. Brown, AJChE Journal, Vol. 34, No. 6, pp. 881-911, 1988, [29]. Reproduced by permission of the American Institute of Chemical Engineers copyright 1988 AIChE.

Fig. 12.18 Vertical Bridgman process with ACRT and periodic solute feeding used for synthesis of homogeneous polycrystalline GalnSb feed.

The next step is to produce nearly perfect single-crystal boules of silicon from the ultrapure polycrystalline silicon. Many techniques have been developed to accomplish this, and they all rely on a similar set of concepts that describe the transport process, thermodynamically controlled solubility, and kinetics [8]. Three important methods are the vertical Bridgman-Stockbarger, Czochralski, and floating zone processes, fully described in Fundamentals of Crystal Growth by Rosenberger [9]. 

Fig. 12.19 Growth process for homogeneous GalnSb single crystals by vertical Bridgman method with ACRT and periodic solute-feeding schemes.

The growing of metal single crystals can be carried out via several methods. Tammann and Bridgman [12] have devised an apparatus for slow solidification of metallic melts. A tube filled with the melt is lowered slowly and at a uniform rate (e.g., by means of a clock mechanism) through a vertical, electrically heated tubular furnace. In order to force the crystallization process to occur at a fixed place and from only one crystallization center, the bottom of the tube is drawn out to a capillary point (Schubnikow Straumanis Cl2]. 

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