TERAHERTZ SPECTROSCOPY OF OPTICALLY THICK MULTILAYERED SEMICONDUCTOR STRUCTURES

Using freely propagating terahertz radiation, we have measured the com plex dielectric constant of optically thick layered materials from 0.2 THz (6.6 cm(-1)) to 6 THz (200 cm(-1)). Transmission measurements of a CdTe-adhesive-Si structure have been successfully fitted to a theore tical model over the measurement range. The accuracy of the theoretica l fit shows that the technique of time-domain spectroscopy offers adva ntages over other spectroscopic methods in the extreme far infrared be low 200 cm(-1) The signal-to-noise capability of our terahertz-spectro scopy technique permits accurate measurement of power transmission coe fficients less than 0.001 (absorption coefficients >5000 cm(-1)) and i ndex variations larger than lambda(dn/d lambda) > 44, as demonstrated by the accurate fit of our data through the Reststrahlen region of CdT e.