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

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4M 1M 2 2 2 T E sin T sin 2 m (3.6) ( M M ) 2 2 1 2 26 From this the differential cross-section d 2pdp may be obtained using the impact parameter p which in turn is determined by using equation 3.6. Following this the nuclear stopping power Sn(E) may be determined by solving equation 3.2 between the limits 0 to the maximum energy transferred 4M M E 1 2 Tm (3.7) 2 ( M 1 M 2 ) In finding Sn(E) the differential cross-section dσ is found which in turn depends heavily on the choice of the interatomic potential V(r) used. Also in most cases the scattering integral cannot be solved analytically and numerical methods should be employed which brings with it an added complexity. The most widely used theory in the prediction of ion ranges in a solid is the LSS theory developed by Linhard, Scharf and Schiott. In the following section the main results of this theory will be discussed but it is left to the reader to consult further references for a more detailed understanding. 3.2.3. The Linhard, Scharff and Schiott (LSS) Theory The LSS theory uses a Thomas-Fermi model of the interaction between heavy ions to derive a nuclear stropping power Sn and electronic stopping power Se. The electronic stopping power is proportional to the velocity of the moving atom since the process of energy loss is dependent on the kinetic energy of the moving atom and the nuclear stopping power is obtained through the procedure shown in the previous section. The interatomic potential used has the form, 2 Z1Z 2e r V ( r) (3.8) 4 r a 0
27 where a = a0(Z1 2/3 + Z2 2/3 ) -½ and is the Thomas-Fermi screening function which is tabulated numerically. An approximation to the function is also given by, r r a (3.9) 2 1 a r 2 2 [ c ] a with c 3 resulting in the best average fit to the potential. Using approximation methods in finding the solution the LSS theory predicts a nuclear stopping power Sn of the form shown in Fig. 3.1. Fig. 3.1. Nuclear and electronic stopping powers in reduced units. Full-drawn curve represents the Thomas-Fermi nuclear stopping power, the dot and dash lines the electronic stopping for k=0.15 and k=1.5. The dashed line gives the nuclear stopping power for the r -2 potential (from Carter et al. (1976)) The energies and distances are expressed in terms of dimensionless parameters ε and ρ given by, aM 2 E (3.10) 2 Z Z e M M ) 1 2 ( 1 2 M M RN4a (3.11) 2 1 2 and 2 ( M 1 M 2 )
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 and 32: 17 Fig. 2.13. The geometrical setup
Page 33 and 34: 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: S n Td (3.2) 25 and is also referr
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
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