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Indexed by:期刊论文

Date of Publication:2015-05-01

Journal:VACUUM

Included Journals:EI、SCIE、ISTIC

Volume:115

Page Number:108-112

ISSN No.:0042-207X

Key Words:Silicon; Low vacuum; Directional solidification; Volatile metal impurities

Abstract:A multicrystalline silicon ingot was obtained from metallurgical-grade silicon after directional solidification under low vacuum condition. The concentration distributions of metal impurities such as copper (Cu), manganese (Mn) and sodium (Na) along the growth direction of the ingot were investigated. The result shows that the concentration of Cu and Mn decrease respectively from 28.56 ppmw and 10.53 ppmw to about 0.1 ppmw and 0.01 ppmw in below 80% of the ingot height, which are in good agreement with the value calculated by the Scheil's equation. The concentration of Na decreases from 1096.91 ppmw to about 0.2 ppmw in the whole ingot, due to the evaporation effect. The evaporation model of Na under low vacuum condition is proposed and the mass transfer coefficient of Na is also calculated. (C) 2015 Elsevier Ltd. All rights reserved.