臺灣博碩士論文加值系統

本論文中介紹由屏東大學(NPTU)與國家同步輻射中心(NSRRC)簽屬正式合約於屏東大學設製分子束磊晶實驗站，並說明分子束磊晶系統的建構計畫，與系統建構期間對研究方向的先行評估測試。利用分子束磊晶系統成長鎳薄膜於藍寶石基板上，依照鍍膜速率、成長時間與基板加熱溫度等條件的改變來成長不同厚度的薄膜。以x光繞射、原子力顯微鏡等儀器分析樣品的結構特性。
分子束磊晶系統的建構中最重的指向方針為材料的蒸鍍的速率，不同的速率影響樣品成長的時間與厚度，此條件對應不同的應用與研究方向。我們將此分子束磊晶系統所使用的三種材料源蒸鍍速率精準的量測與定義，用以判斷所需成長的樣品型式與加熱元件中材料的數量多寡達到間接的觀察監控。
鎳薄膜成長於α-Al2O3為金屬/陶瓷的結構材料，此種結構材料的特性可應用於塗佈或研究其電子自旋等磁特性。Al2O3的基板也常用以成長(111)面的結構，此種薄膜近年來也用以當作石墨烯的基材。X光繞射實驗觀察鎳薄膜成長於藍寶石基板Al2O3(0001)面主要有四支繞射峰(Peak)，利用Peak Indexing可依照繞射峰角度算出晶格間距(d值)，再用Selection rule計算出繞射峰準確的取向，藉此判斷樣品的主要訊號在41.7deg為Al2O3(0006)，在44.6deg為Ni(111)，而前兩根Peak的二倍角在90.7deg是Al2O3(00012)與98.7deg的Ni(222)。判斷Ni薄膜成長於Al2O3(0001)面的垂直晶格取向為Ni(111)晶格面。在實驗結果觀察到52會有訊號峰並隨基板溫度與成膜鍍率不同而有所消長，進一步查表是Ni(200)。各個條件的實驗結果可發現樣品的繞射圖譜中於39deg的位置存相當微小訊號峰(強度約Ni(111)訊號的1/1000倍)，查表發現極近似H.C.P結構的Ni(100)或NiO(110)，而可能形成NiO的原因經判斷是由於我們使用的藍寶石基板為氧終結，因此鍍膜時會在界面形成相當薄的一層NiO，此兩種可能性需待查證。本實驗利用高解析X光繞射實驗與原子力顯微鏡定義出Ni薄膜成長於Al2O3(0001)面上的垂直晶格取向，而水平晶格取向後續會持續研究與討論，並將其正確定義出來。利用繞射圖譜測得的Ni(111)訊號峰的半高寬(FWHM)透過Scherrer's equation計算粒徑並比對AFM量測的薄膜表面晶粒形貌進行討論。

This paper present the construction and the testing of Molecular Beam Epitaxy thin film growth system under the consign agreement between National Pingtung University (NPTU) and National Synchrotron Radiation Research Center (NSRRC). The constructed system is aim to the probing of electronic structure associated with optical, magnetic, and mechanical properties. Our preliminary studies began with photoluminescence (PL) probing of bulk synthesized ZnO with various post annealing conditions, as the signature of the influence of oxygen vacancy. Spectrum weight transfer in the green light region is clearly observed. Epitaxial Ni film was chosen due to its relatively stable in ambient. Epitaxial Ni(111) thin film grown on c-plane Al2O3 were indicated by high-resolution X-ray diffraction. Four main diffraction peaks at 41.7 deg , 44.6 deg , 90.7 deg and 98.7 deg are indexed to Al2O3(0001), Ni(111), Al2O3(00012) and Ni(222), respectively. In particular, tiny signal at 39 deg and 52 deg , ~3 order of magnitude smaller as comparing to Ni(111), are observed. Possible index to 39 deg are NiO(110) or h.c.p Ni(100), while 52 deg is c.c.p. Ni(200). Characterizations based on changing growth rate, substrate temperature, and film thicknesses were fully conducted. Atomic force microscopy reveals reproducible surface morphology according to various growth conditions, indicates the its potential applying to surface costing as well as grapheme substrate. Detail orientation relationship between grown film and substrate is yet to be explored.

致謝 i

中文摘要 ii

英文摘要 iv

圖目錄 vi

表目錄 viii

第一章 導論 1
1.1 研究動機 1
1.2 過度金屬氧化物電子結構 2
1.3 氧化物常見缺陷型態 5
1.4 晶格匹配度 8
1.5 X光繞射原理 10
1.6 X光反射技術 15
第二章 國立屏東大學分子束磊晶系統建構 18
2.1 國立屏東大學分子束磊晶系統建構計畫 18
2.2 真空腔體系統總成 19
2.3 系統元件解構與更換 20
第三章 薄膜成長與量測分析 30
3.1 Ni薄膜成於Al2O3(0001) 30
3.2 實驗設計 32
3.3 AFM表面結構量測 36
3.4 Cu K-alpha X光量測 41
3.5 同步輻射BL07光束線繞射實驗 47
第四章 實驗結果與討論 49
4.1 磊晶鍍率特性曲線 49
4.2 不同成長厚度於薄膜結構特性化 51
4.3 不同成長速率於薄膜結構特性化 54
4.4 不同基板溫度於薄膜結構特性化 56
4.5 晶格取向 60
4.6 磁滯曲線 62
第五章 結果與討論 65
第六章 參考資料 67
第七章 附錄 69
7.1 屏東大學與國家同步輻射中心合作備忘錄 69
7.2 PL操作程序 72
7.3 K-cell拆裝程序 73
7.4 分子束磊晶系統開機S.O.P 75
7.5 分子束磊晶系統關機S.O.P 76

1.Wu, X.L., et al., Photoluminescence and cathodoluminescence studies of stoichiometric and oxygen-deficient ZnO films. Applied Physics Letters, 2001. 78(16): p. 2285.
2.Jeong, S.-H., et al., Photoluminescence dependence of ZnO films grown on Si(100) by radio-frequency magnetron sputtering on the growth ambient. Applied Physics Letters, 2003. 82(16): p. 2625-2627.
3.Janotti, A., et al., Native point defects in ZnO. Physical Review B, 2007. 76(16).
4.Ai, L., et al., Influence of substrate temperature on electrical and optical properties of p-type semitransparent conductive nickel oxide thin films deposited by radio frequency sputtering. Applied Surface Science, 2008. 254(8): p. 2401-2405.
5.Bagnall, D.M., et al., Optically pumped lasing of ZnO at room temperature. Applied Physics Letters, 1997. 70(17): p. 2230-2232.
6.Ohtomo, A., et al., Structure and optical properties of ZnO/Mg sub 0.2 Zn sub 0.8 O superlattices. Applied Physics Letters, 1999. 75(7): p. 980.
7.Powell, R.A., et al., Location of the States in ZnO. Physical Review Letters, 1971. 27(2): p. 97-100.
8.A. F. Kohan, G.C., et al., First-principles study of native point defects in ZnO. Physical Reveiw B, 2000. 61: p. 15019.
9.Alkauskas, A., et al.,Band-edge problem in the theoretical determination of defect energy levels: The O vacancy in ZnO as a benchmark case. Physical Review B, 2011. 84(12).
10.Anisimov, V.I., et al., Density-functional theory and NiO photoemission spectra. Physical Review B, 1993. 48(23): p. 16929-16934.
11.Anisimov, V.I., et al., Band theory and Mott insulators: Hubbard U instead of Stoner I. Physical Review B, 1991. 44(3): p. 943-954.
12.I.A. Nekrasov, M.A.K., et al.,Coulomb interaction in oxygen p-shell in LDA+U method and its influence on calculated spectral and magnetic properties of transition metal oxides. arXiv:cond-mat/0009107v1, 2008.
13.Choi, J.-M., et al., Ultraviolet enhanced Si-photodetector using p-NiO films. Applied Surface Science, 2005. 244(1-4): p. 435-438.
14.陳駿, 分子束磊晶實驗室建構計劃暨執行報告. 2012.
15.C. Tannous , J.G., The Stoner-Wohlfarth model of Ferromagnetism- Static properties.pdf. arXiv:physics/0607117v3, 2008.
16.Anderson, P.W., New Approach to the Theory of Superexchange Interactions. Physical Review, 1959. 115(1): p. 2-13.
17.Nishiyama, T., et al., Growth of Ni Thin Films on Al2O3 Single-Crystal Substrates. Japanese Journal of Applied Physics, 2009. 48(1R): p. 013003.