Comparison of dielectrics and iodine solution for monocrystalline and multicrystalline surface passivation

The effective lifetimes of monocrystalline and multicrystalline wafers were measured under dielectric and iodine-solution surface passivation using inductively coupled photoconductance. While all 18 spots measured on monocrystalline materials had significantly higher (>10%) lifetimes under iodine passivation than dielectric passivation, this condition was satisfied by only 12 of 18 spots measured on cast multicrystalline wafers and just 6 of 18 spots measured on string ribbon. Possible reasons for this behavior are discussed in this paper. Moreover, the differences in surface passivation effectiveness have also been investigated with lifetime maps in order to overcome measurement problems related with the inhomogeneity of ribbon silicon.