Characterization of doped silicon in low carrier density region by terahertz frequency Faraday effect

We report on optical characterization of doped semiconductors by using terahertz Faraday rotation measurements in Cross-Nicole configuration. The detection sensitivity of Faraday rotation angle as small as 0.5 mrad is obtained. The scheme is applied to an n-type silicon wafer of 525 mu m thickness in carrier freeze-out temperature region. The carrier density below N=1x10(14) cm(-3) is evaluated under magnetic field B=1 T. (C) 2008 American Institute of Physics.