Numerical investigation of oxygen impurity distribution during multicrystalline silicon crystal growth using a gas flow guidance device

• Published in: Journal of crystal growth Vol. 360; pp. 12 - 17
• Main Authors: Teng, Ying-Yang, Chen, Jyh-Chen, Lu, Chung-Wei, Chen, Chi-Yung
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Amsterdam Elsevier B.V 01.12.2012; Elsevier
• Subjects: A1. Computer simulation; A1. Heat transfer; A1. Impurities; A1. Mass transfer; Applied sciences; B3. Solar cells; Computational fluid dynamics; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Crystal growth; Defects and impurities in crystals; microstructure; Devices; Energy; Exact sciences and technology; Fluid flow; Gas flow; Growth from melts; zone melting and refining; Impurities; Impurities: concentration, distribution, and gradients; Materials science; Melts; Methods of crystal growth; physics of crystal growth; Natural energy; Photovoltaic conversion; Physics; Solar cells. Photoelectrochemical cells; Solar energy; Structure of solids and liquids; crystallography; Theory and models of crystal growth; physics of crystal growth, crystal morphology and orientation; Vortices; A1. Heat transfer; A1. Mass transfer; A1. Computer simulation; A1. Impurities; B3. Solar cells; Solar cells; Crystal growth; Impurity distribution; Digital simulation; Growth interface; Polycrystals; Crucibles; Photoinduced effect; Computerized simulation; Mass transfer; Quantity ratio; Growth mechanism; Silicon; Growth from melt; Heat transfer
• ISSN: 0022-0248; 1873-5002
• DOI: 10.1016/j.jcrysgro.2011.12.064

Oxygen is one of the most important types of impurities that can cause thermal donor or light-induced degradation in mc-Si solar cells. The objective of this study is to investigate the effect that installing a gas flow guidance device in a mc-Si crystal-growth furnace would have on the oxygen impurity distribution in the melt during the growth process. The installation of such a gas flow guidance device can enhance the gas flow near the free surface, which would allow the argon to carry a greater amount of evaporated SiO gas outside the furnace. Furthermore, the enhanced motion of the gas flow also improves heat transfer near the free surface, which would make the melt vortex separate more easily. The separated melt vortex, which is located near the central region of the melt-crystal interface, directs any oxygen impurity towards the central region of the melt-crystal interface. This is why the oxygen concentration can be reduced by installing the gas flow guidance device. The effectiveness of the gas flow guidance device depends on the vertical distance between it and the free surface (h) as well as the gap between the crucible sidewall and the tip of the device (d). The effect on the oxygen concentration in the melt is significant when smaller values for h and d are adopted. ► The oxygen concentration can be reduced by installing the gas flow guidance device. ► The oxygen depends on the vertical distance h between device and the free surface. ► The oxygen also depends on the gap between the crucible sidewall and device tip d. ► The oxygen decrease is significant when smaller values for h and d are adopted.