Terahertz electromagnetic properties of gold nanoparticles-graphene composite studied by terahertz time-domain spectroscopy

• Main Authors: Liu, Yow-Shiuan, 劉又瑄
• Other Authors: Wu, Kaung-Hsiung
• Format: Others
• Language: zh-TW
• Published: 2015
• Online Access: http://ndltd.ncl.edu.tw/handle/6gnrk4

碩士 === 國立交通大學 === 電子物理系所 === 103 === In this study, terahertz time-domain spectroscopy (THz-TDS) has been used to characterize the THz electromagnetic properties of gold nanoparticles (Au-NPs)-graphene composite. Due to the extraordinary properties, graphene possesses considerable potential as a material for ultrahigh-speed THz optoelectronics devices. In this work, we measure the electromagnetic properties of chemical vapor deposition-grown single-layer graphene decorated by Au-NPs. The optical sheet conductivity is obtained from the measurements of THz-TDS. The experimental data is fitted with the Drude-Smith model in order to extract the dc conductivity and scattering rate. The extracted physical parameters are then used to evaluate the carrier concentration, Fermi energy and mobility of each sample. We find that the sheet conductivity in the THz range enhances as concentration of Au-NPs increases, which is consistent with the theoretical prediction. The induced hole carriers in graphene by decorating Au-NPs can be tuned from 1012 cm-2 to 1013 cm-2, the corresponding Fermi energy is shifted from -140 meV to -479 meV. The changes of scattering rate and mobility with varies carrier concentrations also have been explained.