Analysis of free carrier absorption measurement of electronic transport properties of silicon wafers

Sensitivity analysis of electronic transport property measurement of silicon wafers with modulated free carrier absorption (MFCA) technique and multi-parameter fitting procedure is performed. The sensitivity of the multi-parameter estimate employing the dependences of the MFCA amplitude and phase on the pump-probe-beam separation measured at several modulation frequencies covering an appropriate range is theoretically compared with that employing only the dependences of the MFCA amplitude and phase on the modulation frequency. Simulation results show that the dependences of the MFCA amplitude and phase on the pump-probe beam separation are more sensitive to the electronic transport properties of silicon wafers than the frequency dependences. The electronic transport properties of the silicon wafers determined with the two-beam separation dependence are therefore more accurate than that determined with the frequency dependence. Comparative experiments with a silicon wafer are performed and the carrier lifetime, the carrier diffusivity, and the front surface recombination velocity are determined simultaneously and unambiguously with both techniques.