Characterization of proton beam-irradiated silicon using terahertz time-domain spectroscopy

Abstract

We investigated the electrical properties of n-type silicon with defects produced by proton beam irradiation using terahertz time-domain spectroscopy (THz-TDS). The measured results show a few notable characteristics that lead to better understanding of the quantity and type of defects and their effects on the irradiation proton flux and energy. The THz transmission at first gradually increases with the increase of irradiation proton flux density but then sharply increases above 1013 protons/cm2, possibly resulting from a change in the type of defects. In addition, the increase of THz transmission due to the defect effect is more sensitive to the position of the Bragg peak determined by irradiation proton energy when the irradiation proton flux density is lower than 1014 protons/cm2. Bragg peaks calculated by SRIM simulation and values of carrier density and mobility extracted using a Drude model further clarify the insights obtained from the experimental results.