Pulling crystal growth technique

Fig. 22. A brief classification of R123 crystal growth techniques on a basis of different phenomena taking place at various interfaces between solid, liquid and gaseous phases participating in the solidification process (a) possible interface boundaries and phenomena connected with the presence of such interfaces (b) different interfaces present in the self-flux method note that numbers in brackets correspond to the general scheme of classification (a) (c) a number of interfaces and phenomena of some importance for the unidirectional solidification method note that (crystal-high-temperature phase and melt-high-temperature phase) interfaces are close to each other (d) different interfaces and phenomena to be considered in the SRL-CP pulling technique of bulk crystal production note that solute transport and nudeation can be controlled in order to achieve a desired morphology of the crystal.

Overview of Unit Operations. To maximize the electron or hole (carrier) mobility and thus device speed, ICs are built in single-crystal substrates. Methods of bulk crystal growth are therefore needed. The most common of these methods are the Czochralski and float-zone techniques. The Czochralski technique is a crystal-pulling or melt-growth method, whereas the float-zone technique involves localized melting of a sintered bar of the material, followed by cooling and, thus, crystallization. 

While the growing of single crystals from the melt or the gas pha.se may sometimes be important for industrial purposes (as in the crucible pulling method used for semiconductors such as Si and Ge), in X-ray structure analysis such methods are secondary to crystal growth from solution, and they are employed only when other techniques are not possible. 

Hydrodynamics and computer simulation of crystal growth In the crystal pulling growth technique, two types of convection have to be taken into consideration, namely natural and forced convections (Dupret and Van Den Bogaert 1994). The behavior of the meniscus is also important for the control of the diameter and... 

Within the framework of this chapter, both the description of the principles and merits of the continuous crystal pulling techniques are given and the notions are provided about the hardware for industrial-scale technologies. Separately, we shall dwell on the state-of-the-art technologies, i.e. we shall try both to demonstrate the possibilities of the universal approach to the continuous crystal-growth process and prove that these techniques enable us to vary and modify the level of perfection of the grown single crystal. 

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