論文題目以氧化鋅/氧化鋁的超晶格結構為主，搭配第一原理的計算，成長之樣品必須為全磊晶的超晶格，以原子層沉積去製備樣品，藉著固定每層氧化鋅的厚度，改變氧化鋁的厚度，製程共六個週期，首先以x光反射率搭配GenX軟體的擬合了解每塊樣品的膜厚、密度及粗糙度，並確認樣品皆為超晶格結構後，再以x光繞射及穿透式電子顯微鏡做結構上的分析並討論樣品的磊晶關係，經過量測後夾三層氧化鋁的樣品因在x光繞射中確認為磊晶，在穿透式電子顯微鏡的繞射點再次確認，全系列的樣品中得到此樣品為磊晶超晶格。接著搭配光致螢光光譜以及第一原理計算，發現磊晶超晶格樣品會在氧化鋅的能隙間形成連續中間能帶，將每條中間能帶搭配光致螢光擬合結果，顯示躍遷所釋放的螢光能量是在相同顏色的波長下，在混合各波長的螢光中得到白光的結果，白光為應用價值極高的成果，可進一步搭配LED進行研發步驟進而取代螢光粉。在陰極射線螢光中，得到超晶格樣品的能隙皆在3.7 eV，遠大於單純氧化鋅薄膜的3.2 eV，藉著改變結構從薄膜至超晶格結構，而得到較大的能隙，若能有效藉著兩者比例去控制能隙將提高材料的應用性。從x光電子能譜量測中得到氧和鋁原子容易與大氣中的水氣結合，隨著氧化鋁層的增厚，與大氣中水氣結的比例有明顯的下降，Al 2p的鍵結能也因氧化鋁層的結構從AlO到Al2O3而從較低能量位移到高鍵結能。在價帶量測中，無論從PL或CL所量測的能隙得到導帶與費米能帶間能量，超晶格結構的能量均高於純氧化鋅薄膜，此為氧化鋅的極性所造成的結果，因氧化鋁的加入破壞原先的極性，使能隙變寬，導帶到費米能階的能量自然就變大許多。
關鍵字：氧化鋅、氧化鋁、超晶格、原子層沉積、x光反射率、光致螢光、陰極射線螢光、中間能隙

This dissertation studies the material properties of ZnO/AlO epitaxial superlattice structures with new energy bands, largely contributed by the AlO layers, emerging within the bandgap of ZnO. All the samples were grown by atomic layer deposition (ALD) with ZnO fixed at ~5 nm while the number of AlO atomic layers varies. Excellent conformal epitaxy was found in samples with only a few atomic layers of AlO, which takes the same Wurtzite crystal structure of neighboring ZnO layers. Cathodoluminescence (CL) and photoluminescence (PL) spectroscopy data are consistent with those from the first-principles calculations, as all the mid-gap bands are able to properly account for the observed spectra of photoluminescence. The whitish colors that are pleasant to human eye may be produced as a result for practical lighting applications. Quantized energy bands in the AlO and ZnO multiple quantum-wells structures are analyzed according to the calculated band diagrams and luminescence spectra. Correlations of the findings with the basic material structures as characterizes by X-Ray diffraction and transmission electron microscopy are investigated.

論文審定書 i
Acknowledgment ii
摘要 iii
Abstract iv
Figures viii
Tables xvii
Chapter 1 Introduction 1
1.1 Background 1
1.1.1 Introduction of Superlattices 1
1.1.2 Introduction to ZnO 7
1.1.3 Introduction to Al2O3 10
1.1.4 Introduction to Conformal Epitaxy 14
1.2 ZnO/Al2O3 Multiple layers 18
1.3 Motivation 22
Chapter 2. Experimental Setup 24
2.1 Introduction 24
2.2 Sample Growth 24
2.2.1 Atomic Layer Deposition (ALD) 24
2.3 Structural Measurements 27
2.3.1 X-ray Reflectivity 29
2.3.2 X-ray Diffraction (2θ-ω scan) 34
2.3.3 Phi-Scan (φ-scan) 36
2.3.4 Grazing-angle X-ray Diffraction (GIXRD) 37
2.3.5 Transmission Electron Microscope 38
2.4 Optical Measurement 39
2.4.1 Photoluminescence (PL) 39
2.4.2 Cathodoluminescence (CL) 42
2.4.3 X-ray photoelectron spectroscopy (XPS) 43
Chapter 3 Results and Discussion 44
3.1 Substrates effects on ZnO and Al2O3 thin films 44
3.2 Growth of ZnO/AlOx superlattices 48
3.3 Structural characteristics 50
3.4 Photoluminescence 59
3.5 First-principles calculation 63
3.6 Cathodoluminescence 68
3.7 X-ray Photoelectron Spectroscopy 72
3.7.1 Core Level Analysis 75
3.7.2 Valence Band 83
Chapter 4. Band Structure Analysis 85
4.1 Band Structure of AlO 85
4.2 Electronic Band Structure Analysis of ZnO/AlO Superlattices 86
Chapter 5 Conclusion 93
Reference 95
Appendix 99
A1. X-ray Reflectivity (XRR) Fitting Parameters Comparison 99
A2. X-ray Reflectivity (XRR) Fitting Model Comparison 103
A3. XPS Core Level Fitting Results 105
A4. XPS Valence Band Fitting Results 108
Publications a
Conference Contributions b

[1] L. L.Chang, L.Esaki, W. E.Howard, R.Ludeke, and G.Schul, “Structures Grown by Molecular Beam Epitaxy,” J. Vac. Sci. Technol., vol. 10, pp. 655–662, 1973.
[2] L.Esaki andR. Tsu, “Superlattice and Negative Differential Conductivity in Semiconductors,” IBM J. RES. Dev., pp. 61–65, 1970.
[3] R.Dingle, A. C.Gossard, and W.Wiegmann, “Direct Observation of Superlattice Formation in a Semiconductor Heterostructure,” Phys. Rev. Lett., vol. 34, pp. 1327–1330, 1979.
[4] G. A.Saihalasz, R.Tsu, and L.Esaki, “A new semiconductor superlattice,” Appl. Phys. Lett., vol. 30, p. 651, 1977.
[5] M.Marcinkowski, N.Brown, and R.Fisher, “Dislocation configurations in AuCu3 and AuCu type superlattices,” Acta Metall., vol. 9, no. 2, pp. 129–137, 1961.
[6] R.Dingle, W.Wiegmann, and C. H.Henry, “Quantum States of Confined Carriers in Very Thin AlxGa1-x, As-GaAs-AlxGa1-xAs Heterostructures,” Phys. Rev. Lett., vol. 33, pp. 827–830, 1974.
[7] R.Merlin, K.Bajema, R.Clarke, F. Y.Juang, and P. K.Bhattacharya, “Quasiperiodic GaAs-AlAs Heterostructures,” Phys. Rev. Lett., vol. 55, pp. 1768–1770, 1985.
[8] H.Sakaki, T.Noda, K.Hirakawa, M.Tanaka, and T.Matsusue, “Interface roughness scattering in GaAs/AlAs quantum wells,” Appl. Phys. Lett., vol. 51, p. 1934, 1987.
[9] S.Adachi, “GaAs, AlAs, and AlxGa1-xAs: Material parameters for use in research and device applications,” J. Appl. Phys., vol. 58, 1985.
[10] J. N.Schulman and Yia-Chung Chang, “Band Structure of a Semimetallic HgTe-CdTe Superlattice,” Surf. Sci., vol. 174, pp. 536–540, 1986.
[11] Yia-Chung Chang, J. N. Schulman, G. Bastard, and Y. G. and M.Voos, “Effects of quasi-interface states in HgTe-CdTe superlattices,” Phys. Rev. B, vol. 31, pp. 2557–2560, 1985.
[12] J. N. Schulman and T. C. Mcgill, “Ideal CdTe / HgTe superlattices,” J. Vac. Sci. Techno!., vol. 16, no. 5, pp. 1513–1516, 1979.
[13] J.Reno, I. K.Sou, J. P.Faurie, J. M.Berroir, Y.Guldner, J. P.Vieren, J.Reno, I. K.Sou, and J. P.Faurie, “HgTe layer thickness HgTe-CdTe superlaUices : Experimental and theoretical curves of band gap versus HgTe layer thickness,” Appl. Phys. Lett., vol. 49, pp. 106–108, 1986.
[14] S.Fujita, H.Tanaka, and S.Fujita, “MBE growth of wide band gap wurtzite MgZnO quasi-alloys with MgO / ZnO superlattices for deep ultraviolet optical functions,” J. Cryst. Growth, vol. 278, pp. 264–267, 2005.
[15] S.Fujita, T.Takagi, H.Tanaka, and S.Fujita, “Molecular beam epitaxy of Mg x Zn 1-x O layers without wurzite-rocksalt phase mixing from x=0 to 1 as an effect of ZnO buffer layer,” phys. stat. sol., vol. 241, no. 3, pp. 599–602, 2004.
[16] M. N.Baibich, J. M.Broto, A.Fert, F. N.VanDau, F.Petroff, P.Eitenne, G.Creuzet, A.Friederich, and J.Chazelas, “Giant magnetoresistance of (001)Fe/(001)Cr magnetic superlattices,” Phys. Rev. Lett., vol. 61, no. 21, pp. 2472–2475, 1988.
[17] A.Cebollada, J. L.Martinez, J. M.Gallego, J. J.deMiguel, R.Miranda, S.Ferrer, F.Batallan, G.Fillion, and J. P.Rebouillat, “Antiferromagnetic ordering in Co-Cu single-crystal superlattices,” Phys. Rev. B, vol. 39, no. 13, pp. 9726–9729, 1989.
[18] A.Yamada, B.Sang, and M.Konagai, “Atomic layer deposition of ZnO transparent conducting oxides,” Appl. Surf. Sci., vol. 112, pp. 216–222, 1997.
[19] D. C.Look, “Recent advances in ZnO materials and devices,” Mater. Sci. Eng. B Solid-State Mater. Adv. Technol., vol. 80, no. 1–3, pp. 383–387, 2001.
[20] Z. K.Tang, G. K. L.Wong, P.Yu, M.Kawasaki, A.Ohtomo, H.Koinuma, and Y.Segawa, “Room-temperature ultraviolet laser emission from self-assembled ZnO microcrystallite thin films,” Appl. Phys. Lett., vol. 72, no. 25, pp. 3270–3272, 1998.
[21] P.Erhart, K.Albe, and A.Klein, “First-principles study of intrinsic point defects in ZnO: Role of band structure, volume relaxation, and finite-size effects,” Phys. Rev. B - Condens. Matter Mater. Phys., vol. 73, no. 20, pp. 1–9, 2006.
[22] V.Craciun, J.Elders, J. G. E.Gardeniers, and I. W.Boyd, “Characteristics of high quality ZnO thin films deposited by pulsed laser deposition,” Appl. Phys. Lett., vol. 65, no. 23, pp. 2963–2965, 1994.
[23] Ü.Özgür, Y. I.Alivov, C.Liu, A.Teke, M. A.Reshchikov, S.Doğan, V.Avrutin, S.-J.Cho, and H.Morkoç, “A comprehensive review of ZnO materials and devices,” J. Appl. Phys., vol. 98, no. 4, pp. 1–103, 2005.
[24] J.Lim and C.Lee, “Effects of substrate temperature on the microstructure and photoluminescence properties of ZnO thin films prepared by atomic layer deposition,” Thin Solid Films, vol. 515, no. 7–8, pp. 3335–3338, 2007.
[25] P.V.Chinta, O.Lozano, P.V.Wadekar, W. C.Hsieh, H. W.Seo, S. W.Yeh, C. H.Liao, L. W.Tu, N. J.Ho, Y. S.Zhang, W. Y.Pang, I.Lo, Q. Y.Chen, and W. K.Chu, “Evolution of Metallic Conductivity in Epitaxial ZnO Thin Films on Systematic Al Doping,” J. Electron. Mater., vol. 46, no. 4, pp. 2030–2039, 2017.
[26] L.Qiao, H. Y.Xiao, W. J.Weber, and M. D.Biegalski, “Coexistence of epitaxial lattice rotation and twinning tilt induced by surface symmetry mismatch,” Appl. Phys. Lett., vol. 104, no. 22, pp. 1–6, 2014.
[27] M. D.Groner, F. H.Fabreguette, J. W.Elam, and S. M.George, “Low-Temperature Al 2 O 3 Atomic Layer Deposition,” Chem. Mater., no. 16, pp. 639–645, 2004.
[28] G.Dingemans and W. M. M.Kesselsa, “Status and prospects of Al2O3-based surface passivation schemes for silicon solar cells,” J. Vac. Sci. Technol. A, vol. 30, 2012.
[29] Y.Kim, S. M.Lee, C. S.Park, S. I.Lee, and M. Y.Lee, “Substrate dependence on the optical properties of Al2O3 films grown by atomic layer deposition Substrate dependence on the optical properties of Al2O3 films grown by atomic layer deposition,” Appl. Phys. Lett., vol. 71, pp. 3604–3606, 1997.
[30] A. W.Ott, J. W.Klaus, J. M.Johnson, and S. M.George, “Al3O3 thin film growth on Si(100) using binary reaction sequence chemistry,” Thin Solid Films, vol. 292, no. 1–2, pp. 135–144, 1997.
[31] M. D.Groner, J. W.Elam, F. H.Fabreguette, and S. M.George, “Electrical characterization of thin Al2O3 films grown by atomic layer deposition on silicon and various metal substrates,” Thin Solid Films, vol. 413, no. 1–2, pp. 186–197, 2002.
[32] A. W.Ott, K. C.McCarley, J. W.Klaus, J. D.Way, and S. M.George, “Atomic layer controlled deposition of Al2O3 films using binary reaction sequence chemistry,” Appl. Surf. Sci., vol. 107, pp. 128–136, 1996.
[33] B.Gerard and D.Pribat, “Conformal growth of III-Vs on Si: from low defect density materials to advanced devices,” in Compound Semiconductors 1999, 1999, p. 23.
[34] Z.Hiroi, N.Nakayama, Y.Bando, N.Nakayama, and Y.Sando, “Preparation and structural analysis of a PbSeSnSe strainedlayer superlattice Preparation and structural analysis of a PbSe-SnSe strained-layer superlattice,” J. Appl. Phys., vol. 61, pp. 206–214, 1987.
[35] Y. S.Kim and W. P.Tai, “Electrical and optical properties of Al-doped ZnO thin films by sol-gel process,” Appl. Surf. Sci., vol. 253, no. 11, pp. 4911–4916, 2007.
[36] H.Agura, A.Suzuki, T.Matsushita, T.Aoki, and M.Okuda, “Low resistivity transparent conducting Al-doped ZnO films prepared by pulsed laser deposition,” Thin Solid Films, vol. 445, no. 2, pp. 263–267, 2003.
[37] M. a.Martínez, J.Herrero, and M. T.Gutiérrez, “Deposition of transparent and conductive Al-doped ZnO thin films for photovoltaic solar cells,” Sol. Energy Mater. Sol. Cells, vol. 45, no. 1, pp. 75–86, 1997.
[38] A.Suzuki, T.Masushita, N.Wada, Y.Sakamoto, and M.Okuda, “Transparent Conducting Al-Doped ZnO Thin Films Prepared by Pulsed Laser Deposition,” Jpn. J. Appl. Phys., vol. 35, pp. L56–L59, 1996.
[39] J. M.Jensen, a. B.Oelkers, R.Toivola, D. C.Johnson, J. W.Elam, and S. M.George, “X-ray Reflectivity Characterization of ZnO/Al2O3 Multilayers Prepared by Atomic Layer Deposition,” Chem. Mater., vol. 14, no. 5, pp. 2276–2282, 2002.
[40] J. W.Elam, Z. A.Sechrist, and S. M.George, “ZnO/Al2O3 nanolaminates fabricated by atomic layer deposition: growth and surface roughness measurements,” Thin Solid Films, vol. 414, no. 1, pp. 43–55, 2002.
[41] A. A.Chaaya, R.Viter, I.Baleviciute, M.Bechelany, A.Ramanavicius, Z.Gertnere, D.Erts, V.Smyntyna, and P.Miele, “Tuning Optical Properties of Al2O3/ZnO Nanolaminates Synthesized by Atomic Layer Deposition,” J. Phys. Chem. C, vol. 118, no. 7, pp. 3811–3819, 2014.
[42] R.Viter, I.Iatsunskyi, V.Fedorenko, S.Tumenas, Z.Balevicius, A.Ramanavicius, S.Balme, M.Kempi#ski, G.Nowaczyk, S.Jurga, and M.Bechelany, “Enhancement of Electronic and Optical Properties of ZnO/Al2O3 Nanolaminate Coated Electrospun Nanofibers,” J. Phys. Chem. C, 2016.
[43] M.Leskelä and M.Ritala, “Atomic layer deposition (ALD): From precursors to thin film structures,” Thin Solid Films, vol. 409, no. 1, pp. 138–146, 2002.
[44] S. M.George, “Atomic layer deposition: An overview,” Chem. Rev., vol. 110, no. 1, pp. 111–131, 2010.
[45] M.Knez, K.Nielsch, and L.Niinistö, “Synthesis and surface engineering of complex nanostructures by atomic layer deposition,” Adv. Mater., vol. 19, no. 21, pp. 3425–3438, 2007.
[46] T.Tynell and M.Karppinen, “Atomic layer deposition of ZnO: a review,” Semicond. Sci. Technol., vol. 29, no. 4, p. 43001, 2014.
[47] R. L.Puurunen, “Surface chemistry of atomic layer deposition: A case study for the trimethylaluminum/water process,” J. Appl. Phys., vol. 97, no. 12, 2005.
[48] M.Yasaka, “X-ray thin-film measurement techniques,” Rigaku J., vol. 26, no. 2, 2010.
[49] M.Bjorck and G.Andersson, “GenX: An extensible X-ray reflectivity refinement program utilizing differential evolution,” J. Appl. Crystallogr., vol. 40, no. 6, pp. 1174–1178, 2007.
[50] Hazel Rossotti, Colour: Why the World isn’t Grey. 1985.
[51] M.Wojdyr, “Fityk: a general-purpose peak fitting program,” J. Appl. Cryst., vol. 43, pp. 1126–1128, 2010.
[52] G.Coli and K. K.Bajaj, “Excitonic transitions in ZnO/MgZnO quantum well heterostructures,” Appl. Phys. Lett., vol. 78, no. 19, pp. 2861–2863, 2001.
[53] T.Yan, C.Y. J.Lu, L.Chang, M. M. C.Chou, K. H.Ploog, C.M.Chiang, and N.Ye, “Epitaxial growth of nonpolar m-plane ZnO epilayers and ZnO/Zn0.55Mg0.45O multiple quantum wells on a LiGaO2 (100) substrate,” RSC Adv., vol. 5, no. 127, pp. 104798–104805, 2015.
[54] S.Hüfner, Photoelectron Spectroscopy: Principles and Applications. 2013.
[55] H.Hung-Chun Lai, T.Basheer, V. L.Kuznetsov, R. G.Egdell, R. M. J.Jacobs, M.Pepper, and P. P.Edwards, “Dopant-induced bandgap shift in Al-doped ZnO thin films prepared by spray pyrolysis,” J. Appl. Phys., vol. 112, no. 8, 2012.
[56] A.V.Naumkin, A.Kraut-Vass, S. W.Gaarenstroom, Cedric, and J.Powell, “NIST X-ray Photoelectron Spectroscopy Database 20, Version 4.1,” U.S. Secr. Commer. behalf United States Am., 2012.
[57] G.Dingemans and W. M. M.Kessels, “Status and prospects of Al2O3-based surface passivation schemes for silicon solar cells,” J. Vac. Sci. Technol. A, vol. 30, no. 4, pp. 1–27, 2012.