Microwave whispering-gallery-mode photoconductivity measurement of recombination lifetime in silicon

We present a whispering-gallery-mode resonance-enhanced microwave-detected photoconductivity-decay method for contactless measurement of recombination lifetime in highresistivity semiconductor layers. We applied the method to undoped Silicon wafers of high resistivity at 5 and 30 kOhm*cm and measured the conductivity relaxation times of 10 and 14 microseconds, respectively. In wafers being considered, they are supposed to be defined by the electron-hole diffusion from the bulk to the wafer surfaces.