本文主要在探討不同磊晶結構之金屬-半導體-金屬(MSM)光感測器之特性，在緩衝層使用漸變與階變磊晶結構探討光暗電流比值與響應程度之外，也比較了有無批覆層(Capping Layer)之特性並探討之。我們發現在階變結構上其由於具有能帶不連續處形成障蔽高度導致其暗電流值下降且磊晶品質較好可以使得光暗電流比值提升。在製作具選擇比之光感測器時，批覆了一層Mg0.44Zn0.56O薄膜，做為高阻值且具4.4電子伏特高能隙，能選擇特定波長並將其作為濾波層生長覆蓋於電極之上並探討其對於原本金屬-半導體-金屬光感測器之影響。
在氧化鋅鎂薄膜之材料分析方面，我們經過了不同退火溫度並量測該薄膜之對於各種不同波長之穿透度並經過XRD分析在高溫退火下該晶格之變化趨勢發現角度從34.42°右移至35.3°並透過EDS分析內部元素佐證之。
而在傳統光感測器中，氧化鋅鎂薄膜具有鈍化層之作用可以有效降低暗電流約三個數量級，而且在光暗電流比值上可以達到1.27×105。同時在本身金屬-半導體-金屬光感測器之優點就是具有低雜散電容，而在本文中我們發現批覆氧化鋅鎂薄膜之後該電容值降低了約一個數量級，乃是由於擴散電容降低以及接面缺陷的改良，以提升響應時間。

The Characteristics of the metal-semiconductor-metal (MSM) photodetector with different epitaxial structure were mainly discussed in this paper. One is gradual-buffer MSM structure, the other is MSM with step buffer structure. Both two samples’ P/D ratio and responsibility were compard, and MSM with and without capping layer in step structure were also analyzed. For step buffer structure of fine epitaxial quality, a band discontinuity with obvious barrier height can lower dark current and promoted photocurrent/dark ratio. A Filter layer of Mg0.44Zn0.56O deposited on electrode applied to a wavelength-selection photodetector. It’s a thin film with high resistance and wide band gap of about 4.4eV which cut-off wavelength was suitable for specific designed absorption wavelength.
For thin film materials of Mg0.44Zn0.56O analysis, the transmittance of thin film was measured after high temperature annealing and XRD analysis found that Bragg’s angle changed from 34.42 ° right shift to 35.3 °. Composition of thin films was also examined by EDS .
For conventional photodetector, Mg0.44Zn0.56O with the effect of passivation layer can effectively lower the dark current about three orders in magnitude, and the current contrast ratio can be achieved level of 1.27×105. Metal-semiconductor-metal structures have the original advantages of low stray capacitance, and in this paper Mg0.44Zn0.56O thin film appropriately deposited will decrease the capacitance value about one order in magnitude. The response time was improved due to low leakage current caused by diffusion capacitance decreasing and less interface defects.

目錄

誌謝 ii
摘要 iii
Abstract iv
目錄 vi
表目錄 viii
圖目錄 ix
1.緒論 1
1.1 導論 1
1.2 光感測器介紹 2
1.3 論文架構 4
2.研究背景與理論 6
2.1 氧化鋅鎂材料特性 6
2.2 金半接面理論 9
2.2.1 歐姆接觸與蕭基接觸 9
2.2.2 金半電流傳輸機制 13
2.3 金屬-半導體-金屬光偵測器 15
2.3.1 金屬 半導體 金屬感測器內部電流機制 16
2.3.2 電極幾何構造 24
2.3.3 光響應(Responsivity)與量子效率(Qantum Efficiency) 25
3.元件製作與量測設備 27
3.1 氧化鋅鎂薄膜與製備 27
3.1.1 氧化鋅鎂合成材料比例組成 27
3.1.2 鍍膜系統 28
3.2 元件結構製程 31
3.2.1 磊晶方式 31
3.2.2 磊晶結構 32
3.3 光罩設計與標準黃光製程 35
3.3.1 光罩尺寸設計 35
3.3.2 標準黃光製程步驟 36
3.4 量測儀器介紹 39
3.4.1 光響應量測系統 39
3.4.2 紫外光/可見光光譜儀 39
4.實驗結果與討論 41
4.1 氧化鋅鎂薄膜材料特性之探討 41
4.2 磊晶結構暨電極示意圖 48
4.3 金屬-半導體-金屬光感測器特性 50
4.3.1 暗電流特性比較 50
4.3.2 生長氧化鋅鎂薄膜後之特性比較 52
4.4 具選擇比之UVB波段金屬-半導體-金屬感測器 58
4.5 金屬-半導體-金屬感測器電容值比較 63
5.結論 65
參考文獻 66

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