Low-Cost Purification of Metallurgical Silicon for Photovoltaic Application. | ||||
| MEJ- Mansoura Engineering Journal | ||||
| Article 5, Volume 17, Issue 2, June 1992, Page 13-23 PDF (276.6 K) | ||||
| Document Type: Research Studies | ||||
| DOI: 10.21608/bfemu.2021.167343 | ||||
 View on SCiNiTO | ||||
| Author | ||||
| Roshdy Abou-Alazaam Abderrassoul* | ||||
| Electronic and Communications Engineering Dept., Faculty of Engineering., Mansoura University Mansoura 35516., Egypt. | ||||
| Abstract | ||||
| A new, simple, low-cost technique for the preparation of solar-grade silicon, based on acid-treatment and high-temperature phosphorus-pentoxide gettering of metallurgical-grade silicon for removing the harmful metallic impurities is reported. The starting material is pulverized metallurgical-grade silicon. Purification is achieved by continuously boiling the silicon in a mixture of acids under reflux conditions for about 14 days, replacing the acid by a fresh mixture every 3-5 days. Iron content in the silicon and in the extracted acids has determined using & spectrophotometric technique. Acid leaching was found to be affective in appreciably reducing the content of harmful metallic impurities. Gettering with phosphorus pentoxide was used to achieve further purification of the acid-treated silicon. A thick paste of the acid-leached silicon 5% by weight of phosphorus pentoxide and de-ionized water was heated at 1050 oC for 4 days in a clean quartz container in air. The resulting charge was treated with hydroflouric acid to remove the phosphosilicate glass, and then cleaned and refluxed with agua regia for several days. The iron content in the silicon was further reduced to 150 - 250 ppm. The acid-leached and gettered silicon was used to produce a large area substrate using melting and unidirectional solidification, for solar cell fabrication. The substrate had a resistivity of 0.03 Ԛ c.m and was n-type, making it very suitable for solar cell fabrication. | ||||
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