在本論文中，我們使用兆赫波時間解析系統(Terahertz Time-Domain Spectroscopy, THz-TDS)來研究兩種不同寬度間隔(Spacer Layer)的砷化鎵鋁二維電子氣(AlGaAs Two-Dimensional Electron Gas, 2DEG)的異質結構，並且利用夜態氮(Liquid Nitrogen)來降溫，測量了五種不同溫度下的兆赫波訊號，並計算出兩種不同寬度間隔的複數折射率(Complex Refractive Index)與複數導電率(Complex Conductivity)。最後我們以德汝德模型(Drude Model)對實驗數據做擬合(Fitting)，並計算出載子生命週期(Life Time)、載子濃度(Carrier Concentration)和載子遷移率(Carrier Mobility)。發現砷化鎵鋁二維電子氣隨著溫度上升載子遷移率與載子生命週期有下降的趨勢，載子濃度隨著溫度的上升而變小，且在較薄的寬度間隔載子濃度大於較厚的寬度間隔。

In this thesis, we have studied the two different spacer layer AlGaAs/GaAs heterojunction (two-dimensional electron gas, 2DEG) by using Terahertz Time-Domain Spectroscopy(THz-TDS). In different temperature, we calculate the complex refractive index and complex conductivity. We use Drude model to obtain the parameters of carrier life time, carrier concentration and carrier mobility by fitting experiment data. We found that the carrier mobility and life time will decrease when the temperature rising. However the carrier concentration will decrease when the temperature rising.

論文審定書 i
致謝 ii
摘要 iii
Abstract iv
目錄 v
圖目錄 vi
表目錄 vi
第一章 導論 1
1-1前言 1
1-2砷化鎵鋁二維電子氣介紹 1
1-3兆赫波的發展 3
1-4產生兆赫波方式 5
1-5文獻探討-兆赫波之相關研究 6
第二章 實驗原理 10
2-1光電導偶極天線產生及偵測兆赫波原理 10
2-2光電導偶極天線產生及偵測兆赫波原理推導 10
2-3偵測兆赫波方法以及推導 14
2-4實驗數據分析原理 16
第三章 實驗系統架設 21
3-1實驗光路架設 21
3-2 Mai Tai Laser以及PC-antenna 23
3-3 鎖相放大器(Lock-in，SR850) 25
3-4 Balance Detector 26
第四章 樣品介紹與實驗結果 27
4-1實驗樣品介紹 27
4-2實驗結果 28
第五章 結論 56
參考資料 57

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