The suppression of thermal oscillations in czochralski growth

Abstract The effects of baffles on thermal oscillations in zinc tungstate melts during crystal pulling are described. Two main types of oscillations are found; large transient oscillations (≃ 10 C deg) with irregular periods of several minutes and smaller persistent oscillations (≃ 1 C deg) with periods of a few seconds. The transient oscillations can be eliminated by a variety of baffles. The persistent oscillations can be greatly reduced in amplitude by the use of a flat plate baffle at a height of between one-third and two-thirds of the depth of the melt. The other types of baffle tried either produced no significant reduction or actually increased the amplitude of the persistent oscillations.