本論文研究工作係利用原子沉積系統(Atomic Layer Deposition, ALD) 於c-面藍寶石( Al2O3) 基板上成長AlO/ZnO 超晶格，繼之藉X 射線光電子能譜法（X-ray photoelectron spectroscopy, XPS）測其電子結構。樣品製備條件採氧化鋅的循環數固定在30 次，讓氧化鋁的循環次數n 為變數，其中n = 0, 1, 3, 10,20 。一個30 次循環的氧化鋅對上某個循環次數為n 的氧化鋁被定義為一個週期單位，以這樣的週期成長6 次作成一個AlO/ZnO 超晶格薄膜樣品。經過XRD 分析之後，發現當n=0 或3 的時後，薄膜得以磊晶長成，而且n=3 時Al與O 原子會順著ZnO 依原纖鋅礦晶體結構繼續堆疊。XPS 量測中可針對內層電子或價電子進行量測。由於影響軌道電子能階的絕對位置的因素甚多− 包括光電子發射對不同樣品造成不同靜電效應對費米能階位置的影響。因此，本研究擬訂了一套校正方法，使用不易受環境汙染的純金(Au) 鍍在樣品邊緣作為校正標準，能夠經過兩步驟校正，將費米能階歸零，藉此可以得到有一樣參考點的內層軌道或價鍵帶能階或能帶的相關量。本文對元素的內層電子Zn2p, Zn3d,Al2p, O1s 的束縛能做分析，從中可以得到AlO 的加入後ZnO 的化學結構或物相改變。在價鍵帶電子結構的量測中發現，加入AlO 層會致使ZnO 的極化面消失，從而導致ZnO 的費米能階遠離導帶，且在ZnO 能隙間植入了一些在純氧化鋅中不存在的能階或能帶。因此推測，在ZnO 的費米能階遠離導帶情況下，由XPS 所發現的能隙間態，應該是出自於超晶格之AlO 層的貢獻。此外，本論文最後部分有提到超晶格的電性量測，其之呈半導體特性與由XPS 所得之價鍵帶結構相符合，然與霍爾量測中所得極高的載子濃度相左，這其中與載子濃度的差異可能是源自電流路境，因對變溫電導及霍爾特性的分析均將超晶格視為一均勻連續體，忽略了超薄層的二維效應與層間耦合對電子傳輸的影響。

This thesis work uses atomic layer deposition (ALD) method to grow AlO/ZnO superlattices on c-oriented sapphire (Al2O3) substrates and then tested their electronic structures by X-ray photoelectron spectroscopy (XPS). The samples were made of alternating ZnO and AlO bilayers with numbers of the ZnO cycles held fixed at 30 while letting the AlO cycles n vary from n = 0, 1, 3, 10, to n = 20. Such a bilayer is repeated for 6 times to make a superlattice. X-ray diffraction analysis indicates that the samples grows epitaxially as a whole for n = 0 and n = 3, and, when epitaxial, the AlO layers also assumes the Wurzite structure. As many factors could all affect the absolute position of an energy level, a meticulous calibration procedure was followed using gold as a standard to which the electron binding energies are referenced. Aanalysis of the core levels of Zn2p, Zn3d, Al2p, O 1s in context of any chemical shits found that introduction of the AlO layer could change the overall nature of chemical bonding within ZnO and AlO. Meanwhile, based on the valence band spectra, presence of the AlO in superlattice forms would also diminished the intrinsic electric polarity of the c-oriented ZnO and force the Fermi level to drift away from the conduction band while also bring into the band gap new energy levels or energy bands. Furthermore, magneto-transport measurements put the carrier concentrations on order of 1020 cm-3 for all samples, contradicting with their semiconducting nature judged from the negative slope of the R(T) curves and the distribution of mid-gap states determined by the XPS measurement of the valence band.

1 前言+1
1.1 材料介紹+ 2
1.1.1 氧化鋅+2
1.1.2 氧化鋁+3
1.2 樣品介紹+4
1.2.1 樣品檢測方法+ 4
1.2.2 樣品結構討論+6
2 實驗儀器與理論基礎+8
2.1 原子沉積系統(ALD)+8
2.2 X 光光電子發射能譜儀(X-ray photoelectron spectroscpot, XPS)+11
3 實驗設計與細節+15
3.1 實驗設計+15
3.2 XPS 的校正方法+16
3.2.1 core level-校正方法+16
3.2.2 Valence Band-校正方法+18
4 結果與討論+20
4.1 Core level+20
4.1.1 Au Binding Energy+21
4.1.2 Zn Binding Energy+24
4.1.3 Al Binding Energy+30
4.1.4 O Binding Energy +33
4.2 Valence band +38
4.3 電性量測+45
4.3.1 溫度對電阻變化+46
4.3.2 霍爾效應+50
5 總結+51
Reference +52

[1] Zh.I.Alferov and A.F.loffe, ”Quantum wells and superlattices come of age” ,Physico-Technical Institute, Vol.10 No.7,PP.26-31 (1997)
[2] L. V. Keldysh, ”Effect of ultrasonics on the electron spectrum of crystals” ,Soviet Physics Journal, Vol.4, P.265 (1962)
[3] L. Esaki and R. Tsu, ”Superlattice and negative differential conductivity in Semiconductors” ,IBM Journal of Research and Development, Vol.14, P.63-65 (1970)
[4] R. Dingle, W. Wiegmann, and C. H. Henry, ”Quantum States of Confined Carriers in Very Thin AlxGa1−xAs-GaAs-AlxGa1−xAs Heterostructures” ,Physical Review Letters, Vol.33, p.827-830 (1974)
[5] Marian A. Herman, ”Semiconductor superlattices: physics, crystallization, and applications” ,Liquid and Solid State Crystals: Physics, Vol.1845, P.29-50 (1993)
[6] G. Z. Xing, B. Yao, C. X. Cong, T. Yang, Y. P. Xie, B. H. Li, et al., ”Effect of annealing on conductivity behavior of undoped zinc oxide prepared by rf magnetron sputtering,” Journal of Alloys and Compounds, Vol.457, PP.36-41, (2008)
[7] Shang-Di Mo and W. Y. Ching, ”Eletronic and optical properties of θ-Al2O3
and comparison to α-Al2O3” The American Phiscal Society, Vol.57, P.219-228 (1998)
[8] Prof. Dr. Hadis Morkoç andÜmit Özgür, ”Zinc Oxide: Fundamentals, Materials and Device Technology” ,WILET-VCH ,PP.1-3 (2009)
[9] Michael H. Huang,”Room-Temperature Ultraviolet Nanowire Nanolasers” ,SCIENCE, Vol.292, PP.1897-189 (2001)
[10] Yefan Chen, ”Plasma assisted molecular beam epitaxy of ZnO on c -plane sapphire: Growth and characterization” ,American Institute of Physics, Vol.84, PP.3912-3918 (1998)
[11] T. Hanada, ”Basic Properties of ZnO, GaN, and Related Materials” , Springer Berlin Heidelberg, Vol.292, PP.3 (2009)
[12] Jie Ren, ”Initial growth mechanism of atomic layer deposition of ZnO on the hydroxylated Si(1 0 0)-2×1: A density functional theory study” ,Applied Surface Science, Vol.255, PP.5742–5745 (2009)
[13] E. Guziewicz, M. Godlewski, ”ALD grown zinc oxide with controllable electrical properties” ,Semiconductor Science and Technology, PP.4-7 (2012)
[14] Professor Dr. Stefan Hiifner, ”Photoelectron Spectroscopy Principles and Applications” ,Springer
[15] Thermo scientific, ”K-Alpha: A New Concept in XPS” ,Application Note:31094
[16] Alexander V. Naumkin, Anna Kraut-Vass, Stephen W. Gaarenstroom, Cedric J. Powell, ”NIST X-ray Photoelectron Spectroscopy Database 20, Version 4.1” ,U.S. Secretary of Commerce on behalf of the United States of America (2012)
[17] G. Dingemans, W. M. M. Kesselsa, ”Status and prospects of Al2O3-based surface passivation schemes for silicon solar cells” ,J.Vac.Sci.Technol.A, Vol.30, PP.040802 (2012)
[18] K. H. Tam, C. K. Cheung, Y. H. Leung, A. B. Djurisˇic´, C. C. Ling, C. D. Beling,S. Fung, W. M. Kwok, W. K. Chan, D. L. Phillips, L. Ding, and W. K. Ge ”Defects in ZnO Nanorods Prepared by a Hydrothermal Method” ,J.Phys.Chem.B, Vol.110, PP.20865-20871 (2006)
[19] Parag Banerjee, Won-Jae Lee, Ki-Ryeol Bae, Sang Bok Lee, and Gary W. Rubloff ”MOCVD growth and properties of ZnO films using dimethylzinc and oxygen”, Appl.Phys.A, Vol.81, PP.809–812 (2005)
[20] Parag Banerjee, Won-Jae Lee, ”Structural, electrical, and optical properties of atomic layer deposition Al-doped ZnO films”, Journal Of Applied Physics, Vol.108, PP.043504 (2010)
[21] P. D. C. King„* T. D. Veal, A. Schleife, J. Zúñiga-Pérez, B. Martel, P. H. Jefferson, F. Fuchs, V. Muñoz-Sanjosé, F. Bechstedt, and C. F. McConville ”Valence-band electronic structure of CdO, ZnO, and MgO from x-ray photoemission spectroscopy and quasi-particle-corrected density-functional theory calculations” ,Physical Review B, Vol.79, PP.205205 (2009)
[22] Henry Hung-Chun Lai, Tahseen Basheer, Vladimir L. Kuznetsov, Russell G. Egdell, Robert M. J. Jacobs, Michael Pepper, and Peter P. Edwards ”Dopantinduced bandgap shift in Al-doped ZnO thin films prepared by spray pyrolysis” ,Journal Of Applied Physics ,Vol.112, PP.083708 (2012)
[23] G. Heiland and P. Kunstmann ”Polar surface of zinc oxlde cryscals” ,North-Holland Publishing Co.„ Vol.13, PP.72-84 (1969)
[24] Monu Mishra, T.C. Shibin Krishna, Neha Aggarwal and Govind Gupta ”Surface chemistry and electronic structure of nonpolar and polar GaN films”,Applied Surface Science, Vol.345, PP.440-447 (2015).
[25] Y.Q. Fua, J.K. Luo, X.Y. Du, A.J. Flewitt, Y. Li, G.H. Markx, A.J. Walton,W.I. Milne, ”Recent developments on ZnO films for acoustic wave based biosensing and microfluidic applications: a review”, Sensors and Actuators B:Chemical, Vol.143, pp. 606-619 (2010).