CHEMICAL VAPOR DEPOSITION OF THIN FILM MATERIALS FOR ...

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parameters close to that of the bulk (0.834 nm). This is not surprising considering that the films are relatively thick (> 0.5 μm) and completely relaxed, despite the lattice mismatch with the substrate (~3%). However, the out-of-plane lattice parameter of the film grown at 800˚C is lower than that in the bulk, which indicates the presence of a tensile stress. A stress model for heteroepitaxial magnetic oxide films has been proposed by Besser et al.[160] Depending on the film thickness, the lattice mismatch between the overgrowing film and substrate at the growth temperature cannot withstand the elastic deformation and the stress will be relieved by formation of misfit dislocations at the interface. In this case, assuming elastic behavior for the film, the residual stress after cooling the sample to room temperature is proportional to the difference in the thermal expansion coefficient between the film and substrate and is not related to the bulk lattice parameters. The residual tensile stress of films deposited at 800˚C can be explained well by this model considering that NiFe2O4 has a larger thermal expansion coefficient than MgAl2O4(αMgAl2O4 = 9.5×10 -6 K -1 ). Rocking curve (ω-scan) analysis of NiFe2O4 (400) diffraction is used to characterize the degree of film texture (Fig.42(a)). The measured FWHM (Full Width at Half Maximum) decreases from 0.47˚ to 0.23˚ with increasing growth temperature (FWHM value of MgAl2O4 substrate is ~ 0.02˚). A similar trend in the FWHM has been observed in PLD grown NiFe2O4 films on MgAl2O4 substrates.[102] For films grown on MgO substrates, the FWHM is significantly lower (e.g., 0.03° for film grown at 600°C), likely because of the closer lattice match than MgAl2O4. We have examined the in-plane texture from φ scans of the NiFe2O4 {220} planes. Fig. 42(b) shows the φ scan results of both the NiFe2O4 film and MgAl2O4 substrate (deposited at 600˚C). The four 90˚ spaced diffraction peaks clearly illustrate the four-fold symmetry of the spinel structure. The coincidence of these four peaks with the {220} peaks from 85
the MgAl2O4 substrate confirms cube-on-cube epitaxial growth. The φ scan FWHM values are 0.99˚ and 0.06˚ for the NiFe2O4 film and the MgAl2O4 substrate, respectively. Fig. 41. XRD patterns for NiFe2O4 films deposited on MgAl2O4 (100) at 500, 600, 700 and 800˚C. Peaks with (*) symbol are from MgAl2O4 (h00). Fig. 42. (a) Rocking curves of NiFe2O4 (400) diffraction from films deposited at different temperatures. The FWHM are 0.47, 0.46, 0.36 and 0.23 for the 500, 600, 700 and 800ºC deposited samples, respectively. (b) φ scan for the {220} diffractions of both NiFe2O4 film and MgAl2O4 (100) substrate (deposited at 600ºC). Epitaxial film growth has been further confirmed using polarized Raman spectroscopy measurements. The comparison of the polarized Raman spectra of NiFe2O4 films growth at three different temperatures on MgAl2O4 substrate with those of a bulk NiFe2O4 single crystal is shown in Fig.43. The first and second letters in the notations XX, XY, X’X’, and X’Y’ indicate the polarization of the incident and scattered light, respectively, along the pseudo cubic X||[100], 86
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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
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 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: Fig. 40. Cross-sectional view by fi
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
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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