Minority carrier trapping was investigated in n-type Cz silicon by means of transient-photoconductance (PCD). A simplified Hornbeck and Haynes model was developed for fitting results from transient-PCD to calculate trap density, and it was found to be identical to the model developed for quasi-steady-state photoconductance technique. This indicates that the model can be applied to all photoconductance techniques for lifetime measurement. The results revealed that the trap density is dependent on the concentration of interstitial oxygen and thermal donors, indicating a good agreement with reported results and the results from annealing experiments in this work. Meanwhile, a deep trap energy level was revealed, probably implying that traps also act as recombination centers in n-type silicon. By studying detrapping processes, the concentration of the trapped holes was found to decrease exponentially with time, resulting in a detrapping constant of 167 s.

A new method to map the thermal donor concentration in silicon wafers using carrier density imaging is presented. A map of the thermal donor concentration is extracted with high resolution from free carrier density images of a silicon wafer before and after growth of thermal donors. For comparison, free carrier density mapping is also performed using the resistivity method together with linear interpolation. Both methods reveal the same distribution of thermal donors indicating that the carrier density imaging technique can be used to map thermal donor concentration. The interstitial oxygen concentration can also be extracted using the new method in combination with Wijaranakula's model. As part of this work, the lifetime at medium injection level is correlated to the concentration of thermal donors in the as-grown silicon wafer. The recombination rate is found to depend strongly on the thermal donor concentration except in the P-band region

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