S-Space College of Engineering/Engineering Practice School (공과대학/대학원) Dept. of Electrical and Computer Engineering (전기·정보공학부) Theses (Ph.D. / Sc.D._전기·정보공학부)
Effects of structural parameters on terahertz field enhancement in metal nano slit
금속 나노 슬릿의 구조적 요인이 테라헤르츠 전기장 집속에 미치는 효과
- 공과대학 전기·컴퓨터공학부
- Issue Date
- 서울대학교 대학원
- 학위논문 (박사)-- 서울대학교 대학원 : 전기·컴퓨터공학부, 2016. 2. 박남규.
- Electric field enhancement inside metal-insulator-metal gaps, especially slit structure, is investigated in Terahertz range. Dependencies of field enhancement on slit width and thickness are calculated by modal expansion method for perfect electric conductor approximation and numerical finite difference time domain method for real metal. Field enhancement increases as slit width and thickness decrease. Slit thickness as well as width has a large influence on field enhancement when the width becomes small. To explain the tendencies we propose a model based on charge and capacitor concept. In practice, fabricated metal slit which has a few nanometer sized width usually shows asymmetric and tapered shape due to complexity of fabrication processes. Dependence of field enhancement on tapered angle in symmetric and asymmetric slit is also investigated. Numerical results show that thickness of smallest gap region is the most important for enhancement factor if tapered angle is less than 70 degree. This confined field can be utilized to enhance light-matter interaction. By placing metal nano gap structure on vanadium dioxide film which has transition property between Mott insulator and metal phase at the specific temperature, we can observe enhanced interaction between vanadium dioxide film and terahertz field.