A thermodynamic model for the formation of bubble defects in multicrystalline silicon ingot. (25th February 2017)

• Record Type: Journal Article
• Authors: Gan, Chuanhai; Huang, Liuqing; Lai, Huixian; Sheng, Zhilin; Xing, Pengfei; Luo, Xuetao
• Is Part Of: Applied thermal engineering. Volume 113(2017:Feb.)
• Page Start: 1358
• Page End: 1365
• Publication Date: 2017-02-25
• Subjects: Multicrystalline silicon -- Directional solidification -- Thermodynamics -- Bubble defects -- Nucleation; Heat engineering -- Periodicals; Heating -- Equipment and supplies -- Periodicals; Periodicals; 621.40205
• DOI: 10.1016/j.applthermaleng.2016.11.136
• Languages: English
• ISSNs: 1359-4311

Abstract

Graphical abstract: (a) Bubble defects distribute randomly at the top of multicrystalline silicon ingot; (b) The surface of bubble defects are rough; (c) The surface of bubble defects are covered with many particles. Highlights: Bubble defects distributed randomly at the top of multicrystalline silicon ingot. Bubble defects were caused by gaseous SiO. Heterogeneous nucleation and growth of bubbles were discussed according to thermodynamics. Abstract: Preparation of multicrystalline silicon for solar cells is significant to photovoltaic industry. Up to now, the formation of bubble defects during directional solidification of multicrystalline silicon has not been explored clearly. In the present experiment, spherical bubble defects distributed randomly at ingot top, and the surface of bubble defects was covered with SiC or Si3 N4 particle. A thermodynamic model was proposed to illustrate the formation of bubble defects. Bubble defects were caused by gaseous SiO in silicon melt. SiO was the reaction product of melt silicon and oxygen. Oxygen was dissolved by quartz crucible, diffusing through broken Si3 N4 coatings into silicon melt. Gaseous SiO in the silicon melt nucleated and grew into bubbles against insoluble particles, such as SiC and Si3 N4, and finally enveloped in solid silicon, producing bubble defects. According to the principle of thermodynamics, the formation process was discussed in detail.