Evaluation of surface carrier recombination of optically excited silicon using terahertz time-domain spectroscopy

In this study, the properties of optically excited silicon were investigated using terahertz time-domain spectroscopy (THz-TDS). The surface was illuminated with 365-nm ultraviolet (UV) light to excite charge carriers, and properties such as conductivity, charge carrier density and mobility were evaluated. The illumination effect significantly changed the conductivity as well as the surface recombination velocity (SRV) by altering the surface potential via photoexcited carriers. The SRV observed on the silicon surface varied from 1.56×10 to 3.45×10 cm/s, indicating that UV illumination greatly reduced the SRV depending on the photoexcited carrier density at the silicon surface.