Temperature dependence of minority-carrier lifetime in iron-diffused p-type silicon wafers

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Abstract
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 °C to 230 °C. The lifetime increased monotonically with temperature in nondiffused silicon, while the lifetime in iron‐diffused silicon showed a broad peak around 110 °C and a depression around 170 °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 Ec−0.29 eV was more effective as a recombination center than a hole trap at Ev + 0.1 eV. It was also shown that the effect of iron in concentrations as low as 1×1011 cm−3 on the lifetime can be detected with the noncontact laser/microwave method.