Bulk lifetime determination in high purity silicon by contactless laser technique

The result of bulk lifetime measurements in high purity silicon are presented. For this investigation we offer a new method and technique for determination of the bulk value of the excess carrier lifetime in high purity silicon. The effective value of the lifetime being measured in such a material depends on the dimensions of the ingot.

In our method the sample to be investigated is illuminated by the modulated radiation of the AlGaAs light-emitting diode (LED), which generates the excess carriers, and by the probe beam of the He-Ne laser (λp = 3.39 μm), which becomes modulated when passing through the sample. The bulk lifetime is determined by the analysis of the dependence of the phase shift between these two modulations versus the distance r between the points on the sample surface illuminated by the sources.