CHEMICAL VAPOR DEPOSITION OF THIN FILM MATERIALS FOR ...

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Fig. 19. Unit cell of perovskite BaTiO3 crystal. Due to its ferroelectric property and high dielectric constant, barium titanate has been recognized as a very useful material for certain cutting edge technologies, such as thin film capacitors, magnetoelectric heterostructures, and non-volatile ferroelectric random access memory (FeRAM) devices.[114] Besides, the desirable nonlinear optical properties of BaTiO3 make it attractive for a variety of electro-optic and optical storage device applications.[115] 2.3.2 Review of thin film growth methods Thin film deposition of BaTiO3 has been investigated using different methods, such as RF sputtering,[116-119] evaporation,[120,121] pulsed laser deposition,[122-125] molecular beam epitaxy,[126] sol-gel[127] and chemical vapor deposition.[128-140] The achievement of single crystal, high quality, and good surface morphology has always been the goal for most deposition methods in order to fulfill the requirement of practical devices. Epitaxial growth of BaTiO3 thin films has been found in both physical and chemical vapor deposition methods on different substrates, such as MgO,[117,122,130,135,136,138] TiO2,[123] SrTiO3,[116,136] LaAlO3,[115,131,136] and NdGaO3.[131] Chemical vapor deposition, as mentioned previously, has several advantages over physical vapor deposition. Studies on CVD of BaTiO3 thin films have been reported since early 1990s. Its development has been based on the progress of 45
precursor vaporization process, e.g., better precursors or vaporization techniques. For conventional CVD processes using a heated bubbler or crucible to vaporize liquid or solid precursors (metalorganic, inorganic, alkoxide, etc.), it’s difficult to realize controlled introduction of relatively involatile precursors and the repeatability of thin film growth is poor. The first step towards improvement is to search for or synthesize more volatile and thermal and chemical stable precursors. As for deposition of BaTiO3, titanium tetraisopropoxide (Ti(OC3H7)4, m.p. 20˚C) is used as the Ti source in most CVD processes due to its high volatility, however, the use of the Ba precursor β-diketonate chelate such as Ba(tmhd)2 (thd=2,2,6,6-tetramethyl-3,5- heptandionate) has been limited by its low volatility (m.p.>200˚C) and run-to-run property changes (sintering effect).[115,131,135,138,139] Fluorination and introduction of neutral donator ligands have been found helpful to improve its volatility and reduce the tendency of oligomerization. For instance, Ba(hfa)2(tetraglyme) (hfa=hexafluoroacetylacetonate) and Ba(hfa)2(PEB) (PEB=pentaethyleneglycol ethyl butyl ether), which have melting points of 151˚C and 71˚C, have been synthesized and successfully applied to CVD of BaTiO3 thin films.[115,138] A schematic of barium β-diketonate precursor is showed in Fig.20. Ba Fig. 20. Schematic of a β-diketonate precursor. R' and R'' represent the same or different alkyl groups. 46
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CHEMICAL VAPOR DEPOSITION OF THIN F
Page 3 and 4:
ABSTRACT Chemical vapor deposition
Page 5 and 6:
DEDICATION This dissertation is ded
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φ In-plane tilt angle of X-ray dif
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ACKNOWLEDGMENTS It is my pleasure t
Page 11 and 12:
CONTENTS ABSTRACT .................
Page 13 and 14: 3.2.1 Introduction ................
Page 15 and 16: LIST OF TABLES Table 1. Hafnium ami
Page 17 and 18: indicated by the complex FMR curve.
Page 19 and 20: Fig. 49. Ferromagnetic resonance cu
Page 21 and 22: growth rate, good step coverage and
Page 23 and 24: growth of thin film oxides due to t
Page 25 and 26: one can uniformly deliver precursor
Page 27 and 28: for the next reaction step as shown
Page 29 and 30: Fig. 3. Schematic of a typical dire
Page 31 and 32: is predominantly dependent on syste
Page 33 and 34: J r J A -D n b-n 0 δ n or for the
Page 35 and 36: surface passivation with certain in
Page 37 and 38: ay spectroscopy (EDS), Wavelength d
Page 39 and 40: incidence angle is larger than cert
Page 41 and 42: epresenting those characteristic ph
Page 43 and 44: 1.2.3.3 X-ray Diffraction (XRD) X-r
Page 45 and 46: exhibit diffraction peaks in the no
Page 47 and 48: (nanometers to tens of nanometers),
Page 49 and 50: strongest absorption of microwave s
Page 51 and 52: pinch-off to indicate the lack of a
Page 53 and 54: coupling is from unbound ferrite-fe
Page 55 and 56: diffusion barrier material in micro
Page 57 and 58: Fig. 14. A cross sectional scanning
Page 59 and 60: In spite of the same spinel structu
Page 61 and 62: ferrites has been investigated exte
Page 63: systems is showed in Fig.18.[83] As
Page 67 and 68: CHAPTER 3. PLASMA ENHANCED ATOMIC L
Page 69 and 70: the initial surface chemistry for t
Page 71 and 72: delay time of 2 seconds between spe
Page 73 and 74: Kcal/mol respectively. The stronger
Page 75 and 76: negative slope) behavior in the pum
Page 77 and 78: the existence of both physisorbed a
Page 79 and 80: decomposition products (Hf-H) and g
Page 81 and 82: dried by ultra high purity N2 gas.
Page 83 and 84: pressure for XPS analysis is around
Page 85 and 86: Hf and N elements, incorporation of
Page 87 and 88: [150,151] This is a unique feature
Page 89 and 90: software. The thickness results are
Page 91 and 92: CHAPTER 4. DIRECT LIQUID INJECTION
Page 93 and 94: film growth region. The properties
Page 95 and 96: solution was accurately controlled
Page 97 and 98: size). For the rocking curve analys
Page 99 and 100: oxygen does not participate in the
Page 101 and 102: ecause vapor velocity cannot be cha
Page 103 and 104: Fig. 40. Cross-sectional view by fi
Page 105 and 106: the MgAl2O4 substrate confirms cube
Page 107 and 108: pattern. Fig.44(b) has diffraction
Page 109 and 110: We have used an AGM (Alternating Gr
Page 111 and 112: as derived equations for different
Page 113 and 114: deposited at 600˚C is the lowest.
Page 115 and 116:
wave states degenerate with the FMR
Page 117 and 118:
Fig. 53. ϕ-scan of nickel ferrite
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Surface roughness characterized by
Page 121 and 122:
Fig. 56. X-ray diffraction θ-2θ c
Page 123 and 124:
4.4 Conclusion In summary, we have
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CHAPTER 5. DIRECT LIQUID INJECTION
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eaction zone of the tube furnace is
Page 129 and 130:
Fig. 58. X-ray diffraction characte
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interface. This phenomenon probably
Page 133 and 134:
6.1 Conclusion CHAPTER 6. CONCLUSIO
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the temperature range of 600˚C to
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such as PMN-PT and PZN-PT. CVD proc
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[18]. L. S.-J. Peng, X. X. Xi, B. H
Page 141 and 142:
[54]. B. O. Johansson, J. -E. Sundg
Page 143 and 144:
[96]. J. D. Adam, S. V. Krishnaswam
Page 145 and 146:
[136]. J. Zhao, V. Fuflyigin, F. Wa
Page 147 and 148:
APPENDIX A: LabVIEW PROGRAM FOR PEA
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APPENDIX B: TDMAH MOLECULAR STRUCTU
Page 151 and 152:
H 18 B19 2 A18 1 D17 H 18 B20 2 A19
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