  Muons, as a bulk probe of materials, have been used to study the depth
profile of charge carrier kinetics in Si wafers by scanning the muon
implantation depth. The photoexcited muon spin spectroscopy technique can
optically generate excess carriers in semiconductor wafers, while muons can
measure the excess carrier density. As a result, carrier recombination lifetime
spectra can be obtained. The depth-dependent lifetime spectra enable us to
accurately measure the bulk carrier lifetime and surface recombination velocity
by fitting the spectra to a simple 1-dimensional diffusion model. Unlike other
traditional lifetime spectroscopy techniques, the bulk and surface
recombination properties can be readily de-convoluted in this method. Here, we
have applied the technique to study silicon wafers both with and without
passivation treatment, and have demonstrated that the model can correctly
describe the carrier kinetics in these two cases.
