Contactless Characterization of a Si Wafer with Terahertz Time-Domain Spectroscopy Using a Continuous-Wave Multimode Laser Diode

We demonstrate that the carrier density, scattering time, and wafer thickness of a doped Si wafer can be determined independently by measurement using a sub-THz spectroscopic system with an inexpensive continuous-wave multimode laser diode instead of a femtosecond laser. Because the THz signal spectrum of this system is almost discrete, we propose an improved algorithm for extracting these parameters from experimental data. We also demonstrate the two-dimensional imaging of the carrier-density distribution in the Si wafer.