臺灣博碩士論文加值系統

我們利用濺鍍製程及熱蒸鍍製程成長出純鍺薄膜及鍺掺雜釩與鍺掺雜鈷薄膜，此外也使用加速器產生2MeV之氫離子去撞擊鍺單晶基板，接著藉由能量散佈能譜儀/掃描式電子顯微鏡、原子力顯微鏡、電子順磁共振量測儀、物理性質量測系統以及超導量子干涉磁量儀分析所有鍺薄膜與試片，討論磁性產生的原理。
由能量散佈能譜儀的分析，鍺薄膜或是鍺基板內除了碳與氧外，沒有任何的磁性雜質；由掃描式電子顯微鏡與原子力顯微鏡的結果中，鍺薄膜在低溫成長非常平整，在高溫成長時可以觀察到晶粒生成；由物理性質量測系統的量測結果，電阻率隨著製程溫度升高與掺雜原子的比例提高而有下降的趨勢；由超導量子干涉磁量儀的量測結果，我們不論在鍺薄膜或是鍺基板上都觀測到了居禮溫度高於400K的室溫鐵磁性，且會隨著載子種類的不同而會有不同的磁性強度。另外在氫離子轟擊的鍺基板上發現了鐵磁相與反鐵磁相的共存；由電子順磁共振量測儀的量測，我們得到缺陷造成之未成對電子的訊號。
根據實驗結果與參考的文獻，我們推測磁性是由薄膜或基板內的結構缺陷所誘發產生的，此磁性隨著缺陷的多寡而改變。

Room temperature ferromagnetism was observed in Ge films, Ge：V films, and Ge：Co films deposited by sputtering and thermal evaporation techniques. The same phenomenon was observed in Ge single crystal wafer samples by irradiating with 2MeV proton beams of different fluence range. From the result of EDS, No magnetic impurity was detected in both Ge films and Ge single crystal wafer samples irradiated by proton ion. The image of both SEM and AFM show flat surface on Ge films deposited at low temperature but faceted surface with small grain at higher growth temperature. In the PPMS measurement, the resistivity of Ge films decrease with the higher growth temperature and higher dopant concentration. From the SQUID results, All Curie temperatures are high than 400K. The magnetization in intrinsic Ge, p-type Ge, n-type Ge films, or Ge single crystal wafer samples irradiated by proton beam are different. (The magnetization in the Ge film or single crystal Ge samples irradiated by proton beams were suppressed if they were deposited or post annealing in hydrogen and oxygen). From EPR measurement, we have found the signal of unpaired electrons that produced by defects.
Finally, the ferromagnetism was attribute to the structural defects in the Ge films or single crystal Ge samples. In the single crystal Ge samples irradiated by proton beams, the magnetic moment may have both ferromagnetic and anti-ferromagnetic coupling between the defects, and the oscillation of the magnetic moment indicated the competition between the ferromagnetic and anti-ferromagnetic coupling.

目錄
頁次
誌謝………………………………………………………………… i
中文摘要…………………………………………………………… ii
英文摘要…………………………………………………………… iii
目錄………………………………………………………………… iv
圖目錄……………………………………………………………… vii
表目錄……………………………………………………………… xvi
符號說明…………………………………………………………… xvii
第一章 前言及研究動機………………………………………… 1
第二章 文獻回顧與實驗原理…………………………………… 4
2.1稀釋磁性半導體……………………………………………… 4
2.1.1 稀釋磁性半導體的原理機制…………………………… 4
2.1.2 稀釋磁性半導體的特性與應用………………………… 7
2.2缺陷誘發鐵磁性……………………………………………… 11
2.2.1 缺陷的種類……………………………………………… 11
2.2.2 缺陷誘發鐵磁性的原理與特性………………………… 15
2.3磁性原理……………………………………………………… 22
2.3.1 物質的磁現象…………………………………………… 22
2.3.2 磁性的種類……………………………………………… 22
2.4薄膜概論……………………………………………………… 25
2.4.1 薄膜的特性……………………………………………… 25
2.4.2 薄膜的生長機制與條件………………………………… 25
2.5薄膜材料的性質……………………………………………… 29
2.5.1 鍺的性質………………………………………………… 29
2.5.2 釩的性質………………………………………………… 29
2.5.3 鈷的性質………………………………………………… 29
第三章 實驗流程與實驗儀器…………………………………… 31
3.1實驗流程……………………………………………………… 31
3.1.1 薄膜實驗步驟…………………………………………… 31
3.1.2 離子轟擊實驗步驟……………………………………… 32
3.2實驗儀器……………………………………………………… 34
3.2.1 濺射鍍膜系統…………………………………………… 34
3.2.2 熱電阻式蒸鍍系統……………………………………… 38
3.2.3 范式加速器系統………………………………………… 39
3.2.4 探針薄膜測厚儀………………………………………… 39
3.2.5 掃瞄式電子顯微鏡……………………………………… 40
3.2.6 X光微區分析………………………………………… 42
3.2.7 原子力顯微鏡…………………………………………… 44
3.2.8 超導量子干涉磁量儀…………………………………… 46
3.2.9 物理性質量測系統……………………………………… 48
3.2.10 電子順磁共振量測儀………………………………… 50
第四章 實驗結果與討論………………………………………… 52
4.1 EDS 實驗結果與討論……………………………………… 52
4.2 SEM及AFM 實驗結果與討論…………………………… 62
4.3 SQUID實驗結果與討論…………………………………… 74
4.4 PPM S 實驗結果與討論…………………………………… 107
4.5 EPR 實驗結果與討論……………………………………… 111
第五章 結論……………………………………………………… 115
參考文獻…………………………………………………………… 116

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