臺灣博碩士論文加值系統

近年來，由於一般民用產業及國防工業都需使用更好的紫外光感測器，以用於半導體製程監控(微影儀器校正)、太空通訊、臭氧層的破洞監測、紫外光天文學、火焰感測器、飛彈偵測以及空對空安全通信等應用，這些應用皆需具有高緊密度、高敏感度、高精密性、低功率耗損及高穩定性等特點。
現今的表面聲波元件已被廣泛地應用在各通訊產業上，另外也因為其高靈敏度適用在各類感測器上，而在製作紫外光感測器上，因為氮化鎵與氮化鋁具有寬能隙、低暗電流及高響應度等特性而倍受矚目，本文利用迴旋濺鍍系統在氮化鎵基板上沉積氮化鋁薄膜以製作表面聲波元件，由於氮化鋁薄膜與氮化鎵間晶格不匹配較小（~2.4%），因此能在氮化鎵基板上沉積結晶性較佳的氮化鋁薄膜，並且能改善氮化鎵表面聲波元件之特性，並與半導體、光電產業做結合。本文以此結構製成表面聲波振盪器，探討紫外光之波段及強度對頻率響應及直流特性上之影響，由實驗結果得知，本實驗室所成長之氮化鋁薄膜具有低暗電流（2.58×10-10 A,在10V偏壓下），而表面聲波振盪器具有可偵測波長365nm光源強度之能力。

In recent year, ultraviolet (UV) sensors are attractive due to various civil and military applications, such as semiconductor fabrication (lithography) monitoring、satellite communications、ozone layer monitoring、UV astronomy、flame detection、missile warning and space-to-space communications. High durability、high sensitivity、high compactness、low power and high reliability are critical requirements.
The surface acoustic wave (SAW) device has been used in modern communication. In addition, it suits to be sensors for its high sensitivity. In the region of UV sensors, GaN and AlN are most popular materials because of their wide bandgap、low dark current and high responsivity. In this thesis, AlN thin films were deposited on GaN/Sapphire at the low temperature of 300�aC for SAW devices by using Helicon sputtering system. Due to the small lattice mismatch between AlN and GaN, epitaxial AlN films can be obtained on GaN. Superior SAW characteristics have been observed and demonstrated by depositing AlN on GaN. The thin film layered structure for SAW devices, with the combination of AlN and GaN may, in future, bring about the development of high frequency components which integrate and utilize their semiconducting, optoelectronic properties. The thesis presents a SAW oscillator using this structure. The output frequency of oscillator and the characteristic DC responded to the UV illumination with various wavelengths and intensity will be explored.

目錄
中文摘要 I
Abstract II
致謝 IV
目錄 V
圖目錄 IX
表目錄 XII

第一章 緒論 1
1-1 前言 1
1-2 研究背景與目的 1
第二章 原理 7
2-1 表面聲波元件 7
2-1-1 壓電效應 7
2-1-2壓電材料 9
2-1-2-1 氮化鋁的結構與特性 10
2-1-2-2 氮化鎵的結構與特性 11
2-1-3 表面聲波元件基本原理 13
2-2 表面聲波元件參數 14
2-2-1 波速（Vp） 15
2-2-2 插入耗損（Insertion Loss） 15
2-2-3 機電耦合係數（K2） 16
2-2-4 溫度頻率係數（TCF） 17
2-3 表面聲波元件之感測原理 17
2-3-1 動能密度（Kinetic Energy Density） 18
2-3-2 表面聲波傳遞的干擾 19
2-3-2-1 質量負載效應（MASS LOADING） 23
2-3-2-2 聲電響應（ACOUSTOELECTRIC RESPONSE） 25
2-3-3 光吸收 29
2-3-3-1 光子吸收係數 30
2-3-3-2 電子-電洞對產生速率 32
2-3-4 光吸收與頻率響應之關係 33
第三章 元件製作與量測 35
3-1 氮化鋁薄膜沉積 35
3-1-1 基板清洗 35
3-1-2 氮化鋁薄膜沉積 36
3-1-2-1 迴旋波濺鍍 36
3-1-2-2 迴旋濺鍍系統架構 38
3-1-2-3 薄膜沉積 39
3-1-2-4氮化鋁薄膜分析 41
3-2 層狀結構表面聲波元件之製作 44
3-2-1 指差電極的設計與參數 44
3-2-2 微影蝕刻 45
3-3 頻率響應量測 48
3-3-1 Ｓ參數 49
3-3-2 量測校正 51
3-4 表面聲波振盪器 52
第四章 光感測實驗與分析 56
4-1 表面聲波振盪器穩定度測試 56
4-2 光感測實驗 58
4-2-1 紫外線燈光源之感測 59
4-2-1-1 導電率之改變 60
4-2-1-2 表面聲波元件頻率響應之改變 61
4-2-1-3 表面聲波振盪器之感測 61
4-2-2 氘燈光源之感測 64
4-2-2-1 導電率之改變 66
4-3 實驗結果討論 67
第五章 結論 71
5-1 結論 71
5-2 未來展望 71
參考文獻 73

圖目錄
圖2-1 表面聲波在彈性固體上運動 7
圖2-2 正壓電效應 8
圖2-3 逆壓電效應 9
圖2-4 氮化鋁基本結構 11
圖2-5 氮化鎵基本結構 13
圖2-6 表面聲波元件傳輸特性 14
圖2-7 機械波傳遞在ZnO基板上所造成的電場改變 19
圖2-8 當一功率密度P的聲波穿過單位體積內時所儲存的能量 20
圖2-9 表面聲波傳遞在壓電基板上所產生之電場 26
圖2-10 導電膜在表面聲波元件上的聲電響應之等效電路圖 26
圖2-11 導電膜之片電導與波速及衰減之改變量的關係圖 28
圖2-12 光產生電子—電洞對的形成 30
圖2-13 在一微長度之中的光吸收 31
圖2-14 両個吸收係數的光子強渡對距離的圖形 32
圖3-1 迴旋波示意圖 37
圖3-2 迴旋濺鍍系統 38
圖3-3 迴旋濺鍍系統架構圖 39
圖3-4 濺鍍氮化鋁實驗流程圖 40
圖3-5 不同溫度下氮化鋁薄膜沉積在氮化鎵基板上之XRD圖 42
圖3-6 在300℃下沉積氮化鋁薄膜沉積在氮化鎵基板上之XRD 42
圖3-7 AlN(101)、GaN(101)、Sapphire(104) ψ方向掃描量測圖 43
圖3-8 指叉電極 45
圖3-9 微影蝕刻實驗之流程圖 48
圖3-10 表面聲波元件頻率響應之量測圖 49
圖3-11 雙埠網路訊號流程圖 50
圖3-12 SOLT校正板示意圖 52
圖3-13 振盪電路架構 53
圖3-14 放大器MAN-1LN增益S21量測圖 55
圖4-1 表面聲波振盪器頻譜圖 56
圖4-2 表面聲波振盪器實作成品 57
圖4-3 表面聲波振盪器穩定度測試 57
圖4-4 高強度紫外線燈 59
圖4-5 在UV燈照射下，氮化鎵之光電流與暗電流 60
圖4-6 表面聲波振盪器照射UV燈之頻譜圖 62
圖4-7 在UV燈照射下，振盪器對不同光源強度之頻率飄移 63
圖4-8 振盪器對UV燈光源之反應速率 63
圖4-9 氘鎢鹵素燈之光源強度 65
圖4-10 氘鎢鹵素燈 65
圖4-11 在氘燈照射下，氮化鋁之光電流與暗電流 66
圖4-12 層狀結構表面聲波元件的聲電響應之等效電路圖 68

表目錄
表2.1 不同壓電基板之表面聲波元件對質量負載的靈敏度 24
表3.1 濺鍍氧化鋁之最佳參數表 41
表3.2 指叉電極設計之參數 45
表3.3 放大器MAN-1LN資料表 54
表4.1 Power meter之資料表 58
表4.2 高強度紫外線燈經Power meter量測所得之光源強度 60
表4.3 氘鎢鹵素燈之規格表 64
表4.4 氘燈經Power meter量測所得之光源強度 66

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