Measurement of complex optical constants of a highly doped Si wafer using terahertz ellipsometry

We propose and demonstrate a terahertz (THz) time-domain spectroscopy combi ned with ellipsometry. The complex optical constants of a Si wafer with low resistivity are deduced from the measurements of the wave forms of reflect ed s- and p-polarized THz pulses without reference measurement. The obtaine d dispersion of refractive index above similar to0.2 THz shows good agreeme nt with that predicted by the Drude theory. The complex optical constants d educed by the THz ellipsometry in the low-frequency region are strongly aff ected by the slight error of the ellipsometric angle originating mainly fro m the misalignment of the rotation angles of the polarizer and analyzer. (C ) 2001 American Institute of Physics.