Characterising Zinc Telluride wafers using continuous-wave terahertz spectroscopy

Using a two-colour, continuous-wave terahertz (THz) source, we present a non-contact, non-destructive method for characterising the crystal parameters of Zinc Telluride (ZnTe) wafers. The high and low frequency dielectric constants and plasma and phonon frequencies of ZnTe wafers of differing thickness are found by fitting a simple model to the transmittance as a function of frequency. The dielectric function used in the fitting function invokes phonon, plasma and atomic contributions, which have not been considered simultaneously in previous work. The continuous-wave THz source allows for higher resolution at lower frequencies than is achievable with conventional pulsed-wave techniques.