Flow-symmetry breaking owing to buoyancy effects in cold-wall stagnation flow CVD reactors has been studied through numerical simulations. The underlying mechanisms and the process windows in which it may occur have been determined. For reactor height-to-diameter aspect ratios larger than one, and Rayleigh numbers (based on the reactor diameter) between 2 x 10~3 and 10~5, symmetry-breaking may occur, which can be suppressed through an increase in the inlet flow and/or rotation rate of the susceptor, corresponding to Ra/(Re~2Pr) < 50.
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