Far-infrared conductivity of CuS nanoparticles measured by terahertz time-domain spectroscopy

This paper reports that terahertz time-domain spectroscopy is used to measure the optical properties of CuS nanoparticles in composite samples. The complex conductivity of pure CuS nanoparticles is extracted by applying the Bruggeman effective medium theory. The experimental data are consistent with the Drude--Smith model of conductivity in the range of 0.2--1.5~THz. The results demonstrate that carriers become localized with a backscattering behaviour in small-size nanostructures. In addition, the time constant for the carrier scattering is obtained and is only 64.3~{fs} due to increased electron interaction with interfaces and grain boundaries.