화학공학소재연구정보센터
Journal of Crystal Growth, Vol.237, 1840-1843, 2002
Containerless crystallization of silicon
Crystallization from undercooled melt of silicon was carried out by means of electro-magnetic levitation method under controlled undercooling. The measured growth rate vs. undercooling was categorized into three regions. I, II and III, respectively. from the point of the interface morphology. Thin plate crystals whose interface consisted of both faceted (1 1 1) plane and wavy edge plane like saw-tooth were observed in the region I where the undercooling is less than 100 K. The growth rate of the wavy edge plane was well described by the dendrite growth model. The morphology of growing crystals was abruptly changed to faceted dendrite in the region II, though there was no abrupt change in the growth rate. Seeding at temperatures in the region I changes the drop to a mono-crystalline sphere, if the growth rate alon- the normal direction ofthe thin plate crystal is controlled by step-wise growth on the facetcd planc. Actually, the sample of 5 mm in diameter seeded at undercooling of 26 K was a quasi-single crystal with large grain, except for a small area where twinning and cracking are observed. The result suggests that the single crystal could be grown, if a smaller sample, 1 or 2 mm in diameter, that is difficult to be levitated by electro-magnetic force were processed with other methods such as free fall in a drop tube. (C) 2002 Elsevier Science B.V. All rights reserved.