Aluminum Co-Doping Method to Increase the Boron and Phosphorous Concentration Limits Allowed in Silicon Feedstock for Solar Cells

作者：You Yuliu^*; Morita Kazuki

来源：Materials Transactions, 2017, 58(10): 1439-1443.

DOI：10.2320/matertrans.M2017149

• solar energy materials
• compensation theory
• directional solidification
• segregation coefficient
• grain boundaries

In the present work, an aluminum co-doping method was employed to improve the electrical properties of multi-crystalline silicon containing phosphorous and boron. The method is based on the compensation theory and on the different segregation coefficients of aluminum (k(Al) = 2.8 x 10(-3)), boron (k(B) = 0.8), and phosphorous (k(P) = 0.35) in silicon during solidification. The carrier type and carrier concentration throughout the height of the silicon ingot with co-doping of aluminum were measured. The results show that no polarity inversion occurs and a relatively low carrier concentration, i.e., low net doping concentration can be achieved with aluminum co-doping. Moreover, the resistivity and minority carrier lifetime throughout the height of the silicon ingots with and without co-doping of aluminum were measured. The results show that a relatively high and uniform resistivity and minority carrier lifetime can be achieved by adding a controlled amount of aluminum. In addition, the effect of the grain boundary on the electrical properties was studied.

• 出版日期2017