Electromagnetic levitation refining of silicon–iron alloys for generation of solar grade silicon

Abstract

At present, expensive semiconductor grade silicon (SEG-Si) is used for the manufacture of cells to convert solar energy into electricity. This results in a high cost for photovoltaic electricity compared to electricity derived from conventional sources. The processing of inexpensive metallurgical silicon, or ferrosilicon alloys, is a potentially economical refining route to produce photovoltaic silicon. With phosphorus being one of the most difficult impurities to remove by conventional techniques, this project investigated the use of electromagnetic levitation for dephosphorization of silicon–iron alloy droplets exposed to hydrogen–argon gas mixtures. The effects of time, temperature, hydrogen partial pressure, iron content in the alloy, and initial phosphorus concentration were evaluated.