Analysis of the extended defects in 3C-SiC.pdf - Nelson Mandela ...

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72 Table 7.1. The values used in calculating the camera length. Rm is the measured values in arbitrary units using measuring software and R is the actual values in meters obtained by using the scaling factor. A value of 5.43Å was used for the lattice parameter of Si. Index Rm R (in m) λL (in m 2 ) 93.49 0.007805 2.45E-12 93.49 0.007805 2.45E-12 91.39 0.00763 2.39E-12 91.39 0.00763 2.39E-12 107.27 0.008956 2.43E-12 107.27 0.008956 2.43E-12 Average 2.42E-12 Table 7.2. The values used in calculating the lattice parameter of SiC. Rm is the measured values in arbitrary units using measuring software and R is the actual values in meters obtained by using the scaling factor. Index Rm R (in m) dhkl (in m) Lattice parameter (in m) 116.37 0.009715 2.49E-10 4.32E-10 115.86 0.009673 2.51E-10 4.34E-10 115.90 0.009676 2.50E-10 4.34E-10 114.67 0.009573 2.53E-10 4.38E-10 133.69 0.011161 2.17E-10 4.34E-10 132.43 0.011056 2.19E-10 4.38E-10 Average 4.35E-10 ± 0.02E-10 Using this procedure, the lattice parameter of the SiC was determined by taking an average of the parameters obtained using all the and diffraction spots present in the pattern. The lattice parameter was found to be 4.35Å ± 0.02Å. Furthermore from the orientation relationship between the two sets of diffractions spots it is clear that exact epitaxial orientation between the two materials were obtained during growth with the following orientation relationship {001}Si || {001}SiC and Si || SiC. Fig. 7.1 also shows evidence of planar defects originating at the interface and extending into the bulk of the SiC. This was confirmed by a high resolution TEM study of the interface shown in Fig. 7.3.
73 Fig. 7.3. A HRTEM image of the SiC/Si interface with FFTs taken of the Si and SiC (inserted) The inserts are the images obtained from fast Fourier transforms (FFT) taken of the areas indicated. These FFTs are essentially reconstructed images of diffraction patterns of the areas resulting from the fact that in a TEM the images in the diffraction plane are Fourier transforms of that in the image plane and vice versa. Thus these patterns may also be used to determine the lattice parameter of the SiC. Using the same technique as above and a value of 4.35Å± 0.01Å was found. Evidence of defects originating at the interface and propagating along {111} planes is seen. The origin of these defects has been ascribed by Powell et al. (Section 5.3.2) to the accommodation of the lattice and thermal mismatch between the SiC layer and Si substrate. This process takes place through the introduction of misfit dislocations and twins. Due to the high density of twins and stacking faults at the SiC/Si interface the misfit dislocations could not be resolved at the interface.
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Analysis of the Extended Defects in
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My sincere thanks to the following
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OPSOMMING Hierdie dissertasie hande
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4.2.5. Two-Beam Scattering Matrix 4
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Dedicated to my wife and parents
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SUMMARY The dissertation focuses on
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CONTENTS Chapter 1: INTRODUCTION 1
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1 CHAPTER ONE INTRODUCTION Silicon
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2.1. Introduction 3 CHAPTER TWO OVE
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2.2.2 The Zinc-Blende Structure 5 T
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2.3 Point Defects, Defect Migration
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v m Em vm0 exp( ) (2.2) kT 9 wher
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11 explained and the concept of par
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13 Straight dislocations furthermor
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2.5 Partial Dislocations and Slip 1
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17 Fig. 2.13. The geometrical setup
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19 extrinsic stacking faults are th
Page 35 and 36: 2.8 Twinning 21 Twinning is a proce
Page 37 and 38: 23 Fig. 2.20. The process of vacanc
Page 39 and 40: S n Td (3.2) 25 and is also referr
Page 41 and 42: 27 where a = a0(Z1 2/3 + Z2 2/3 ) -
Page 43 and 44: 29 Using this expression, curves of
Page 45 and 46: 31 As stated previously hard-sphere
Page 47 and 48: 33 where A is the atomic weight. Th
Page 49 and 50: 35 a vacancy dislocation loop if th
Page 51 and 52: 37 Fig. 4.1. (a) A wave incident on
Page 53 and 54: 39 Consider Fig. 4.2 which illustra
Page 55 and 56: 41 V0 is the mean inner potential o
Page 57 and 58: 43 beam left-hand side g' = 0 g' =
Page 59 and 60: 45 In addition another set of indep
Page 61 and 62: 47 When this is incorporated into t
Page 63 and 64: S ( s , z ) e T i Se ( / 0 )
Page 65 and 66: z0 z2 . xn cos and (4.47) D 1 proj
Page 67 and 68: 5.1 Introduction 53 CHAPTER FIVE LI
Page 69 and 70: 55 different orientations. The inte
Page 71 and 72: 57 Furthermore Pirouz et al. (1987)
Page 73 and 74: 59 intersection of the fault, the f
Page 75 and 76: 61 each nuclei because of the low s
Page 77 and 78: 63 (2000) found that subsequent ann
Page 79 and 80: 6.3.1 Ion Range and Defect Producti
Page 81 and 82: 67 Fig. 6.3. Total number of displa
Page 83 and 84: 7.1 Introduction 69 CHAPTER SEVEN R
Page 85: Fig. 7.2. Simulated diffraction pat
Page 89 and 90: 75 Fig. 7.5. The stacking fault sel
Page 91 and 92: (Si/ni) 2 0.000018 0.000016 0.00001
Page 93 and 94: 79 may be concluded that the initia
Page 95 and 96: 81 Fig. 7.11. Bright field TEM micr
Page 97 and 98: 83 Fig. 7.12 which was obtained by
Page 99 and 100: 85 Fig. 7.13. Bright-field TEM micr
Page 101 and 102: 87 (a) (b) Fig. 7.15. The (a) exper
Page 103 and 104: 89 In the following paragraphs the
Page 105 and 106: Fig. 7.18. CBED pattern taken of th
Page 107 and 108: 93 Table 7.5. The measured paramete
Page 109 and 110: 7.4.2 Results 95 Fig. 7.22. Bright-
Page 111 and 112: 97 Twin platelets on {111} planes
Page 113 and 114: 99 REFERENCES Blumenau, A.T., Jones
Page 115 and 116: 101 Hull, D., Bacon, D.J. : (1984)
Page 117: 103 Smith, D.J., Jepps, N.W. and Pa
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