CHEMICAL VAPOR DEPOSITION OF THIN FILM MATERIALS FOR ...

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MgAl2O4, the Ms value decrease with increasing deposition temperature, which might result from interface diffusion of Mg elements at high temperatures. The in plane FMR line width of these films range from 900 to 1100 Oe showing decreasing trend with increasing temperature. The improved surface roughness at high temperatures might contribute to the smaller FMR line width. Annealing of these as deposited films at 1000˚C in air for certain time range (2 and 4 hrs) has also been carried out to monitor the FMR line width change. All the films after annealing show increased FMR line width, which is different from those reported results of PLD deposited nickel ferrite films on MgO(111) substrate.[101] Fig. 55. Epitaxial growth of nickel ferrite films on SrTiO3 (100), PMN-PT (100) and PZN-PT(100) substrates at 600˚C measured by XRD θ-2θ scan. Peaks with * are from (h00) reflections of the underlying substrates. Nickel ferrite thin film growth on piezoelectric (ferroelectric) substrates SrTiO3 (100), PMN-PT (100) and PZN-PT (100) are also investigated. All of these materials have a perovskite structure with lattice constants of 3.905, 4.023, and 4.06 (for ideal cubic phase). The corresponding lattice mismatch of nickel ferrite to these substrates are 6.4%, 3.5% and 2.5%, respectively. DLICVD of nickel ferrite on these substrates have been carried out at 600˚C. Epitaxial growth of nickel ferrite films has been observed, as shown in Fig.55. Film growth rate around 700 nm/hr is achieved by using the same vaporizer conditions as deposition on MgAl2O4. 99
Surface roughness characterized by AFM showed much smoother growth on SrTiO3 (~1 nm) than those on PMN-PT and PZNPT (~20 nm). Considering the similar atomic flat substrate surface and film thickness, these difference of film surface roughness should be attributed to different thin film growth mode due to different substrate surface energies. In-plane FMR measurement (9.5 GHz) of nickel ferrite films deposited on these piezoelectric substrates show FMR line width in the range of 800 to 1000 Oe. While the out-of-plane FMR curves are greatly distorted, which indicates more defects/inhomogeneities in the as deposited thin films. 4.3 DLI-CVD Growth of LiFe5O8 Films Lithium ferrite has the same inverse spinel structure as nickel ferrite, but it possesses a much narrower FMR line width, which indicates very small microwave loss behavior. So far, most of the reported lithium ferrite thin film deposition are based on physical vapor deposition methods or liquid phase epitaxy.[89,93] No reports has been found by using metal organic chemical vapor deposition technique. Our research on DLI-CVD of lithium ferrite films is novel and can contribute to the understanding of thin film growth mechanism and proper processing conditions. In our research, Li(acac) and Fe(acac)3 are used as the metal organic precursors, both of which are dissolved in DMF solvent in a molar ratio of 1:5. Typical vaporization and processing conditions are listed in table 7. Most of the conditions are the same as those used for deposition of nickel ferrite except for the concentration of the precursor solution. Thin film deposition on MgAl2O4 (100) and MgO (100) are investigated in the temperature range of 500˚C to 800˚C. The results of XRD characterization of as deposited films are showed in Fig.56. The results indicate that epitaxial growth of lithium ferrite on MgO (100) can be obtained at all of the four temperatures. Only (h00) reflections from lithium ferrite have been observed. As showed in 100
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CHEMICAL VAPOR DEPOSITION OF THIN F
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ABSTRACT Chemical vapor deposition
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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
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CONTENTS ABSTRACT .................
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3.2.1 Introduction ................
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LIST OF TABLES Table 1. Hafnium ami
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indicated by the complex FMR curve.
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Fig. 49. Ferromagnetic resonance cu
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growth rate, good step coverage and
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growth of thin film oxides due to t
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one can uniformly deliver precursor
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for the next reaction step as shown
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Fig. 3. Schematic of a typical dire
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is predominantly dependent on syste
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J r J A -D n b-n 0 δ n or for the
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surface passivation with certain in
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ay spectroscopy (EDS), Wavelength d
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incidence angle is larger than cert
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epresenting those characteristic ph
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1.2.3.3 X-ray Diffraction (XRD) X-r
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exhibit diffraction peaks in the no
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(nanometers to tens of nanometers),
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strongest absorption of microwave s
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pinch-off to indicate the lack of a
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coupling is from unbound ferrite-fe
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diffusion barrier material in micro
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Fig. 14. A cross sectional scanning
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In spite of the same spinel structu
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ferrites has been investigated exte
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systems is showed in Fig.18.[83] As
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precursor vaporization process, e.g
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: Fig. 53. ϕ-scan of nickel ferrite
Page 121 and 122: Fig. 56. X-ray diffraction θ-2θ c
Page 123 and 124: 4.4 Conclusion In summary, we have
Page 125 and 126: CHAPTER 5. DIRECT LIQUID INJECTION
Page 127 and 128: eaction zone of the tube furnace is
Page 129 and 130: Fig. 58. X-ray diffraction characte
Page 131 and 132: interface. This phenomenon probably
Page 133 and 134: 6.1 Conclusion CHAPTER 6. CONCLUSIO
Page 135 and 136: the temperature range of 600˚C to
Page 137 and 138: such as PMN-PT and PZN-PT. CVD proc
Page 139 and 140: [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
Page 149 and 150: 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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