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

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CBED 76 Fig. 7.6. shows an annotated micrograph of a CBED pattern recorded using a 400 reflection at the area containing the stacking fault. Fig. 7.6. An annotated CBED micrograph used in the determination of the foil thickness The distances measured on the original negative are indicated on the figure. The values calculated according to the technique outlined in De Graef (2003) are given in Table 7.3 with corresponding plotted values and the associated linear trend line given in Fig. 7.7. Table 7.3. The measured parameters with calculated variables used in obtaining Fig. 7.7. ni Δθi Si (nm -2 ) 1/ni 2 (Si/ni) 2 (nm -2 ) 2 0.36 0.0050 0.250 6.31667E-06 3 0.80 0.0111 0.111 1.38637E-05 4 1.13 0.0157 0.063 1.55589E-05 5 1.47 0.0205 0.040 1.68515E-05
(Si/ni) 2 0.000018 0.000016 0.000014 0.000012 0.00001 0.000008 0.000006 0.000004 0.000002 0 77 y = -4.99E-05x + 1.89E-05 R 2 = 9.95E-01 0 0.05 0.1 0.15 0.2 0.25 0.3 (1/ni) 2 Fig. 7.7. The plotted values of Table 7.1 with the linear trend line used to determine the foil thickness and extinction distance From the trend line the values of extinction distance and foil thickness can be determined from the slope and y-intercept of the graph respectively by taking the square root of the inverse of the associated value. The extinction distance was found to be 142 nm and foil thickness 230 nm. Electron Diffraction (2003) calculates the extinction distance of the 400 reflection in 3C-SiC to be 138 nm and is thus in good agreement with the obtained value. The value found for foil thickness using the thickness fringe method agrees well with that of the CBED technique but the value found by the latter should be taken as the more accurate one. Following this the anomalous absorption ratio of the material was chosen. This ratio affects the image contrast characteristics in the bright and dark-field image and may lead to incorrect conclusions if the wrong value is used for the image simulations. A value between that of diamond and silicon was assumed since no theoretical value could be found in literature. A value of 0.055 was used. The values of diamond and silicon are ~ 0.01 and ~ 0.1 respectively and can be calculated by finding the ratio of the absorption length to that of the extinction distance which in turn could be found by various software packages such as JEMS - Electron Microscopy Software.
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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
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2.8 Twinning 21 Twinning is a proce
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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 and 86: Fig. 7.2. Simulated diffraction pat
Page 87 and 88: 73 Fig. 7.3. A HRTEM image of the S
Page 89: 75 Fig. 7.5. The stacking fault sel
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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