Time-domain modulated free-carrier absorption measurements of recombination process in silicon wafers

A time-domain modulated free-carrier absorption (MFCA) is developed both experimentally and theoretically to investigate the photo-carrier dynamics of silicon wafers illuminated by a square-wave-modulated super-band-gap laser beam. An explicit three-dimensional (3-D) theoretical expression for the temporal behavior of the MFCA signal is obtained by solving a 3-D carrier-diffusion equation The time-domain MFCA model is used to fit the experimental MFCA signals of p- and n-type Si wafers via a multi-parameter fitting procedure to determine simultaneously the electronic transport properties, that is, the bulk lifetime, the ambipolor diffusivity, and the front surface recombination velocity. The uncertainties of the fitted parameter values are estimated.