反射式太赫茲光譜於多頻感測器與化合物半導體光電特性量測之應用

Abstract

近年來太赫茲的研究非常興盛，太赫茲時域光譜(THz-TDS)因具有非接觸和非破壞性等優點，被廣泛的應用在各種材料量測上，但是對於一些高摻雜的化合物半導體以及超材料吸收器等光無法穿透的材料，反射式的系統就顯得相當重要。於是我們利用反射式太赫茲時域光譜(THz-TDRS)量測高摻雜化合物半導體的複數折射率以及電導率，並利用Drude-Smith model來擬合電導率，求出材料的電漿頻率與載子散射時間，並用這兩個參數得到材料的載子濃度與載子遷移率。我們還設計了一種可以用於反射式太赫茲時域光譜量測的超材料，近年來超材料因其卓越調製太赫茲的能力而備受關注，但由於其晶胞尺寸大小的關係，使得太赫茲超材料受到傳統微奈米製程的限制，傳統的製程有著步驟繁瑣、耗時以和昂貴的設備等問題，為了克服這些困難，我們提出了一種基於3D列印設計的太赫茲超材料感測器，並利用簡單的雙狹縫設計達到多頻感測器的功能，我們利用有限元素法模擬了超材料的吸收頻譜、電磁場的分佈還有對於血液成分的感測能力，並且說明了元件製程的可能性。本論文主要分為兩個部分，第一個部分主要為第三代半導體的光電特性量測，第二部分為基於3D列印的超材料感測器模擬。In recent years, research in the field of terahertz has experienced remarkable growth. Terahertz Time-Domain Spectroscopy (THz-TDS) has gained widespread use in various material measurements due to its non-contact and non-destructive advantages. However, for materials like highly doped compound semiconductors and metamaterial absorbers, which do not allow THz penetration, reflective systems have become crucial. As a result, we employed Reflective Terahertz Time-Domain Spectroscopy (THz-TDRS) to measure the complex refractive index and conductivity of highly doped compound semiconductors. We utilized the Drude-Smith model to fit the conductivity, allowing us to determine the material's plasma frequency and carrier scattering time. These two parameters were then used to derive the material's carrier concentration and carrier mobility. Furthermore, we designed a metamaterial tailored for reflective THz-TDS measurements. Metamaterials have garnered significant attention for their exceptional ability to manipulate terahertz waves. However, due to constraints imposed by the size of their unit cells, traditional micro/nano fabrication processes have limited the development of terahertz metamaterials. These conventional processes are intricate, time-consuming, and involve expensive equipment. In order to overcome these challenges, we proposed a terahertz metamaterial sensor based on 3D printing. We achieved multifrequency sensing through a simple dual-slit design. By employing finite element analysis, we simulated the metamaterial's absorption spectrum, distribution of electromagnetic fields, and its capability for sensing blood components. Additionally, we discussed the feasibility of the device fabrication process. This thesis is divided into two main parts. The first part focuses primarily on the optical and electronic characterization of third-generation semiconductors. The second part involves simulating a metamaterial sensor based on 3D printing.