2017 Volume 58 Issue 10 Pages 1439-1443
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 (kAl = 2.8 × 10−3), boron (kB = 0.8), and phosphorous (kP = 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.
