利用同調兆赫光譜研究金屬薄膜的電性轉換及銀奈米線薄膜的熱穩定性

Abstract

In this thesis, the terahertz time-domain spectroscopy (THz-TDS), which is an optical and non-contact method, was utilized to elucidate the complex THz conductivity and dielectric responses of thin Au film and Ag nanowires. During the growth of thin Au films, we observed the characteristic crossover from an insulator behavior to a conductor behavior via the percolation transition. From the divergent behavior of carrier scattering time and the increase of persistence of velocity parameter, the critical film thickness at which crossover from Drude to non-Drude behavior of THz conductivity occurs could be determined. Meanwhile, for metallic nanostructures, it is essential to understand their thermal stability during the growth and device fabrication process. We have studied the thermal stabilities of ohmic contacts in silver nanowire (NW) films by measuring both sheet resistance and THz conductivity up to 200oC. We compared the thermal stability of as-grown AgNW films with that of AgNW with a graphene overlayer and found that graphene can effectively dissipate the heat and improve the thermal stability of AgNW films.

In this thesis, the terahertz time-domain spectroscopy (THz-TDS), which is an optical and non-contact method, was utilized to elucidate the complex THz conductivity and dielectric responses of thin Au film and Ag nanowires. During the growth of thin Au films, we observed the characteristic crossover from an insulator behavior to a conductor behavior via the percolation transition. From the divergent behavior of carrier scattering time and the increase of persistence of velocity parameter, the critical film thickness at which crossover from Drude to non-Drude behavior of THz conductivity occurs could be determined. Meanwhile, for metallic nanostructures, it is essential to understand their thermal stability during the growth and device fabrication process. We have studied the thermal stabilities of ohmic contacts in silver nanowire (NW) films by measuring both sheet resistance and THz conductivity up to 200oC. We compared the thermal stability of as-grown AgNW films with that of AgNW with a graphene overlayer and found that graphene can effectively dissipate the heat and improve the thermal stability of AgNW films.