Rotation pancake

Fig. 22. Schematics of chemical vapor deposition epitaxial reactors (a) horizontal reactor, (b) vertical pedestal reactor, (c) multisubstrate rotating disk reactor, (d) barrel reactor, (e) pancake reactor, and multiple wafer-in-tube reactor (38).

The deformation can be very complicated to describe in a single-particle framework, but a good understanding of the basic behavior can be obtained with an overall parameterization of the shape of the whole nucleus in terms of quadmpole distortions with cylindrical symmetries. If we start from a (solid) spherical nucleus, then there are two cylindrically symmetric quadmpole deformations to consider. The deformations are indicated schematically in Figure 6.10 and give the nuclei ellipsoidal shapes (an ellipsoid is a three-dimensional object formed by the rotation of an ellipse around one of its two major axes). The prolate deformation in which one axis is longer relative to the other two produces a shape that is similar to that of a U.S. football but more rounded on the ends. The oblate shape with one axis shorter than the other two becomes a pancake shape in the limit of very large deformations. 

Modeling of Miscellaneous CVD Reactors. In addition to the classical CVD reactor configurations discussed in the preceding sections, a wide variety of CVD reactor configurations have been used, including barrel and pancake-type reactors for epitaxy and vertical cross-flow LPCVD reactors. Barrel reactors have often been modeled as horizontal reactors, because the flow geometry of one barrel side is similar to that of a horizontal reactor (Table 3 in reference 212). However, the similarity disappears if buoyancy effects and barrel rotation are included in the analysis. 

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