Continuous-Wave Terahertz Spectroscopy as a Non-Contact Non- Destructive Method for Characterising Semiconductors

Using the technique of terahertz photomixing, a continuous-wave terahertz source is used to characterise various semiconductors in the frequency range from 0.06 to 1.0 THz. By directly analysing the interference pattern of the transmission through semiconductor wafers using Fabry-Perot theory, information regarding the carrier concentration, sample thickness and refractive index is obtained without physically altering the sample. The continuous-wave technique enables measurements to be made at much lower frequencies than achievable with traditional pulsed-wave terahertz techniques.