我們以van der pauw Hall量測在溫度77 K的電子遷移率與載子濃度分別是9328 cm2/Vs以及7.917 1012 cm-2的異質結構樣品Al0.18Ga0.82N/GaN，進行高電子移動率電晶體(High Electron Mobility Transistor;HEMT)元件的製程，並且將元件線寬縮小至奈米線等級，來研究當二維電子氣(two-Dimensional Electron Gas;2DEG)變成低維度時元件閘極偏壓所造成的電子傳導特性。從SdH量測中可以清楚的觀察到SdH的振盪並且計算出載子濃度，發現樣品0922GaN-200 nm與0922GaN-100 nm在溫度0.39 K時的FFT圖可以經由Non-linear Curve Fit出兩個高斯函數的疊加波，推測是由自旋分裂所造成，這也形成SdH圖形當中的拍頻現象。但閘極偏壓改變並沒有造成明顯的趨勢變化，我們認為是元件氧化層品質不佳以及氧化層厚度太厚所造成的影響。

We have fabricated the device of High Electron Mobility Transistor(HEMT) on Al0.18Ga0.82N/GaN heterostructures. The mobility of 2DEG of the AlGaN/GaN is 9328 cm2/Vs and carrier concentration is 7.917 1012 cm-2 obtained by conventional van der pauw Hall measurement at temperature of 77 K. We made the conducting channel of nanometer wires on the AlGaN/GaN heterostructures for researching low-dimensional transport of two-Dimensional Electron Gas by gate controlled. From the SdH measurement, we can clearly observe the SdH oscillations and obtain the SdH frequencies. For the sample of 0922GaN-200 nm and 0922GaN-100 nm at 0.39 K,two constituted peaks of Gauss’s function were fitted by Non-linear Curve and Two SdH oscillations beat each other, probably due to spin-splitting. However, we can’t discover any trend in the experiment of gate controlled. In the future, we will try to improve the quality and discover the suitable depth of SiO2.

第一章 簡介 1
1-1前言 1
1-2 半導體異質結構特性 2
1-3 AlGaN/GaN異質結構 4


第二章 原理 5
2-1 3He系統降溫原理 5
2-2 Rashba and Dresselhaus effect 7


第三章 實驗儀器 10
3-1 實驗儀器簡介 10
3-2 杜瓦瓶的主要構造及功能 12
3-3 3He Insert 15
3-4 實驗室管路配置 19


第四章 實驗步驟 22
4-1 準備工作 22

4-1-1 檢查所有實驗儀器 22
4-1-2 抽真空夾層 25
4-1-3 抽液氦傳輸管(transfer tube) 27
4-1-4 Insert 的準備 28
4-2 預冷 30
4-3 傳輸液氮至液氮層 32
4-4 傳輸液氦 33
4-4-1 清空液氦層的液氮 33
4-4-2 檢查針閥 34
4-4-3 傳輸液氦至液氦層 35
4-5 樣品層降溫與變溫 41
4-5-1 降溫 41
4-5-2 變溫(僅供參考) 44
4-6 電腦程式量測與接線 47
4-7 實驗結束工作 48
4-7-1 將Insert抽出杜瓦瓶 48
4-7-2 將Insert放入杜瓦瓶 50
4-7-3 結束SdH 實驗量測 52



第五章 實驗結果分析與討論 53
5-1 實驗動機 53
5-2 實驗樣品 54
5-3 實驗結果分析 56
5-3-1 Sample 0922GaN-900 nm 57
5-3-2 Sample 0922GaN-500 nm 60
5-3-3 Sample 0922GaN-300 nm 64
5-3-4 Sample 0922GaN-100 nm 68
5-3-5 Sample 0922GaN-200 nm 77
5-3-6 Non-linear Curve Fit以及FFT注意事項 85


第六章 結果與討論 87


Reference 89

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