CHEMICAL VAPOR DEPOSITION OF THIN FILM MATERIALS FOR ...

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tetragonal shape, which indicates the existence of large tensile stress thin the film. This apparent strain phenomenon will affect the internal magnetic field and thus change the resonance field. The much smaller T1 term of 800 ˚C than those of other temperatures coincides with this strain effect very well. Another behavior is the increasing magnetocrystalline anisotropy field ( with increasing deposition temperature, which might be attributed to the increased single crystal quality of the as deposited thin films. The as listed spectroscopic splitting g factor (also known as Landé g factor) has a relationship with the gyromagnetic ratio: 93 , in which and are Bohr magneton and reduced Planck constant, respectively. The values of as calculated g factor are slightly greater than 2, which has been also reported for experimental measurement of other ferrite materials.[168] Table 6. Structural and magnetic properties of nickel ferrite films deposited at different temperatures. Structural and magnetic parameters Growth temperature (˚C) 500 600 700 800 In-plane lattice parameter a (Å) 8.354±0.002 8.346±0.002 8.348±0.003 8.366±0.001 Out-of-plane lattice parameter c (Å) 8.338±0.001 8.343±0.001 8.342±0.001 8.318±0.001 Saturation magnetization 4 MS (G) 3230 3280 3569 3757 g factor 2.24±0.003 2.27±0.01 2.28±0.009 2.28±0.03 2K1/MS (G) -75±15 -228±46 -272±38 -328±111 4 Meff (G) 2348±14 2560±46 2883±38 889±108 The line width of FMR resonance curve represents the degree of microwave loss which is an important concern for practical microwave device application. Nickel ferrite films deposited on MgAl2O4 at different temperatures were characterized by in plane FMR (static magnetic field pointing at [100] direction) at microwave frequency of 9.5 GHz. The as measured thin film thickness is in the range of (650~780 nm). As one can see in Fig.49, the FMR line width of film )
deposited at 600˚C is the lowest. One important factor contributing to single crystal thin film FMR line width is the surface roughness. This is probably the reason why films deposited at higher temperatures show larger FMR linewidth. Another possible reason is interface diffusion of Mg element from the substrate to the film at higher temperatures. Effect of chemical impurities on FMR line width of ferrite materials has been widely investigated.[169,170] It's noteworthy that the increased single crystal quality at higher temperatures is compromised by the decreased FMR performance. Thin film deposited at 500˚C also shows larger FMR line width than that of 600˚C. This might be attributed to the low single crystal quality and different ion distribution in nickel ferrite lattice structure resulted from limited surface diffusion behavior at low temperatures. Fig. 49. Ferromagnetic resonance curve of nickel ferrite films deposited on MgAl2O4 substrate at different growth temperatures. (Sample size 5 mm × 5 mm, thickness 650~780 nm) The inset shows the profile of FMR line width with thin film growth temperature. Due to the smallest FMR line width of films deposited at 600˚C, angle and frequency dependence FMR behavior of film deposited at this temperature is characterized. The angle dependence of in plane FMR line width measured at 9.5 GHz shows four-fold symmetry (Fig.50), which coincides with the cubic structure of nickel ferrite as measured by XRD ϕ scan. In this 94
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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
Page 61 and 62: ferrites has been investigated exte
Page 63 and 64: systems is showed in Fig.18.[83] As
Page 65 and 66: 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: as derived equations for different
Page 115 and 116: wave states degenerate with the FMR
Page 117 and 118: Fig. 53. ϕ-scan of nickel ferrite
Page 119 and 120: 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
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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