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

More documents

Recommendations

Info

18 The polarity of the broken bonds in both situations differ and thus the α dislocation is positive and the β negative. Accordingly they will have different mobilities and activation energies. The dotted lines in the figure indicate the extra (double) half- planes of Ga-As atoms which generate the edge component of the two types of dislocations. 2.7 Stacking Faults A stacking fault is a planar defect in which the regular stacking sequence of a local region within the crystal has been disrupted. These faults are mainly introduced due to plastic deformation through mechanical or thermal strain but may also be introduced into a crystal during a CVD growth process. Stacking faults are not expected in an ABABAB… type stacking sequence since no alternative configuration for an A layer resting on a B exists. However stacking faults are possible in the ABCABC… type stacking sequence since alternate stacking configurations do exist. This is frequently seen in the close-packed {111} planes for the fcc and zinc-blende structures. Fig. 2.15. The (a) intrinsic and (b) extrinsic stacking faults in an fcc lattice (from Hull et al. (1984)) (a) (b) Two types of stacking faults are possible, termed intrinsic and extrinsic. Intrinsic stacking faults are formed as a result of the removal of a layer in the stacking sequence, as shown in Fig. 2.15(a) where part of a C layer has been removed, and
19 extrinsic stacking faults are the inverse of intrinsic and relates to the insertion of an extra layer between two existing layers as in Fig. 2.15(b) where an A layer has been inserted between a C and B. Fig. 2.16. A description of the modification of the stacking sequence in a lattice due to the presence of intrinsic and extrinsic stacking faults (from Käckell et al. (1998)) Furthermore if an intrinsic stacking fault is introduced by the removal of a B layer for example, it creates a stacking sequence ABCA/CABC which correlates to only one modified layer (Fig. 2.16.). When a C layer for example is inserted between an A and B such as in the case of an extrinsic stacking fault it creates a stacking sequence ABCA/C/BCABC which implies the modification of two layers.
Page 1 and 2: Analysis of the Extended Defects in
Page 3 and 4: My sincere thanks to the following
Page 5 and 6: OPSOMMING Hierdie dissertasie hande
Page 7 and 8: 4.2.5. Two-Beam Scattering Matrix 4
Page 9 and 10: Dedicated to my wife and parents
Page 11 and 12: SUMMARY The dissertation focuses on
Page 13 and 14: CONTENTS Chapter 1: INTRODUCTION 1
Page 15 and 16: 1 CHAPTER ONE INTRODUCTION Silicon
Page 17 and 18: 2.1. Introduction 3 CHAPTER TWO OVE
Page 19 and 20: 2.2.2 The Zinc-Blende Structure 5 T
Page 21 and 22: 2.3 Point Defects, Defect Migration
Page 23 and 24: v m Em vm0 exp( ) (2.2) kT 9 wher
Page 25 and 26: 11 explained and the concept of par
Page 27 and 28: 13 Straight dislocations furthermor
Page 29 and 30: 2.5 Partial Dislocations and Slip 1
Page 31: 17 Fig. 2.13. The geometrical setup
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 and 86:
Fig. 7.2. Simulated diffraction pat
Page 87 and 88:
73 Fig. 7.3. A HRTEM image of the S
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
show all

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

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?