TEMPERATURE-DEPENDENCE OF MINORITY-CARRIER LIFETIME IN IRON-DIFFUSED P-TYPE SILICON-WAFERS

Minority-carrier recombination lifetime was measured with a noncontact laser/microwave method for nondiffused and iron-diffused p-type silicon wafers in the temperature range from 28-degrees-C to 230-degrees-C. The lifetime increased monotonically with temperature in nondiffused silicon, while the lifetime in iron-diffused silicon showed a broad peak around 110-degrees-C and a depression around 170-degrees-C. The temperature dependence of the lifetime in iron-diffused silicon was analyzed based on Shockley-Read-Hall statistics. The origin of the lifetime temperature dependence was attributed to the dissociation of iron-boron pairs. Our experimental data supported that an electron trap for an iron-boron pair at E(c) - 0.29 eV was more effective as a recombination center than a hole trap at E(v) + 0.1 eV. It was also shown that the effect of iron in concentrations as low as 1 x 10(11) cm-3 on the lifetime can be detected with the noncontact laser/microwave method.