Bridgman Growth

The primary advantage to the Bridgman-Stockbarger method is the ability to control the solidification rate, the position and shape of the solidification front, and the thermal gradient at the solidification front. It is also an important research tool for studying the details of various aspects of the solidification process individually and in a controlled manner so that we can learn the rules needed to imderstand and control the more complicated processes. 

A variation of the Bridgman method is the gradient freeze method. In the simplest case, the base of the ampoule sits on a quench block or otherwise cooled. The temperature of the furnace is gradually lowered in a controlled manner, which decreases the temperature gradient in the sample and advances the solidification isotherm. Single crystal turbine blades are usually grown in this manner. The advantage is simplicity—there are no 

Schematic of a Bridgman-Stockbarger furnace with an adiabatic zone. Heat flows into the melt from the hot zone, through the solidification interface in the adiabatic zone, and is extracted through the solid in the cold zone as indicated by the arrows. The growth ampoule is slowly lowered at the desired solidification velocity. In order to maintain a near-planar solidification front, the solidification interface is kept in the adiabatic zone where the isotherms are nearly perpendicular to the walls. 

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In Bridgman growth [155], a boat or vessel filled with the melt is slowly cooled from one side, so that the crystal forms from that side. In Czochralski growth [156,157] a cylindrical crystal sits on the surface of the melt and is slowly pulled upward. In both cases the hydrodynamical flow of the melt is an important factor in the chemical composition and fine structure of the resulting crystal. 

Figure 9. Thermocouple measurement as a function of time with increasing strength of an applied transverse magnetic field in a vertical Bridgman growth system by Kim (62). Oscillations are damped by the field.

Lan, C. W. (2005), Flow and segregation control by accelerated rotation for vertical Bridgman growth of cadmium zinc telluride ACRT versus vibration, J. Crystal Growth, 274 (3-4), 379-386. 

Local Fe states (using MOssbauer spectroscopy) and thermal expansion coefficient in FeIn2S4 single crystals grown by the directional crystallization of the melt (vertical Bridgman growth) have been studied. 

S. Brandon and J. J. Derby, Internal Radiative Transport in the Vertical Bridgman Growth of Semitransparent Crystals," J. Cryst. Growth, 110, pp. 481-500,1991. 

CONSTRAINED UNIDIRECTIONAL GROWTH OF BINARY ALLOYS 2.1. Bridgman growth... 

P. Rudolph, 1995, Eundamental studies on Bridgman growth of CdTe , Prog. Cryst. Growth Charact. 29, 275-381. 

P. Rudolph, F. Matsumoto, T. Fukuda, 1996, Studies on interface curvature during vertical Bridgman growth of InP in a flat-bottom container , /. Cryst. Growth 158, 43-48. 

Application of the accelerated crucible rotation technique to the Bridgman growth of CdxHgi xTe simulations and crystal growth ,... 

Fig. 5.2 Ratio between the simulated actual growth rate growth snd the translation rate Rtranslation versus normalized crystal length for the Bridgman growth of CdZnTe for two different crystal diameters. The translation rate of the ampoule Rtranslation relative to furnace is constant and was used as input parameter in the QSS simulations.

In Bridgman-type crystal-growth configurations one possibility to control convection and therefore the shape of the solid/liquid interface, as well as the dopant distribution, is the so-called accelerated cmcible rotation technique (ACRT). This technique was developed by Scheel [56] and has been applied especially to the Bridgman growth of CdHgTe and CdZnTe crystals, e.g. [57, 58). 

Kohda, and M. Sasaura, 1989, Liquid encapsulated. Vertical Bridgman growth of large diameter, low dislocation density, semi-insulating GaAs , J. Cryst. Growth 94, 643-650. 

D. T. J. Hurle, 1995, A Mechanism for Twin Formation during Czochral-ski and Encapsulated Vertical Bridgman Growth of III-V Compound Semiconductors , J. Cryst. Growth 147, 239-250. 

Use of Forced Mixing via the Accelerated Crucible Rotation Technique (ACRT) in Bridgman Growth of Cadmium Mercury Telluride (CMT)... 

I 77 Useof Forced Mixing via the ACRT in Bridgman Growth of CMT Bridgman... 

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