Analysis of the extended defects in 3C-SiC.pdf - Nelson Mandela ...
Analysis of the extended defects in 3C-SiC.pdf - Nelson Mandela ...
Analysis of the extended defects in 3C-SiC.pdf - Nelson Mandela ...
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(Si/ni) 2<br />
0.000018<br />
0.000016<br />
0.000014<br />
0.000012<br />
0.00001<br />
0.000008<br />
0.000006<br />
0.000004<br />
0.000002<br />
0<br />
77<br />
y = -4.99E-05x + 1.89E-05<br />
R 2 = 9.95E-01<br />
0 0.05 0.1 0.15 0.2 0.25 0.3<br />
(1/ni) 2<br />
Fig. 7.7. The plotted values <strong>of</strong> Table 7.1 with <strong>the</strong> l<strong>in</strong>ear trend l<strong>in</strong>e used to determ<strong>in</strong>e<br />
<strong>the</strong> foil thickness and ext<strong>in</strong>ction distance<br />
From <strong>the</strong> trend l<strong>in</strong>e <strong>the</strong> values <strong>of</strong> ext<strong>in</strong>ction distance and foil thickness can be<br />
determ<strong>in</strong>ed from <strong>the</strong> slope and y-<strong>in</strong>tercept <strong>of</strong> <strong>the</strong> graph respectively by tak<strong>in</strong>g <strong>the</strong><br />
square root <strong>of</strong> <strong>the</strong> <strong>in</strong>verse <strong>of</strong> <strong>the</strong> associated value. The ext<strong>in</strong>ction distance was found<br />
to be 142 nm and foil thickness 230 nm. Electron Diffraction (2003) calculates <strong>the</strong><br />
ext<strong>in</strong>ction distance <strong>of</strong> <strong>the</strong> 400 reflection <strong>in</strong> <strong>3C</strong>-<strong>SiC</strong> to be 138 nm and is thus <strong>in</strong> good<br />
agreement with <strong>the</strong> obta<strong>in</strong>ed value. The value found for foil thickness us<strong>in</strong>g <strong>the</strong><br />
thickness fr<strong>in</strong>ge method agrees well with that <strong>of</strong> <strong>the</strong> CBED technique but <strong>the</strong> value<br />
found by <strong>the</strong> latter should be taken as <strong>the</strong> more accurate one.<br />
Follow<strong>in</strong>g this <strong>the</strong> anomalous absorption ratio <strong>of</strong> <strong>the</strong> material was chosen. This ratio<br />
affects <strong>the</strong> image contrast characteristics <strong>in</strong> <strong>the</strong> bright and dark-field image and may<br />
lead to <strong>in</strong>correct conclusions if <strong>the</strong> wrong value is used for <strong>the</strong> image simulations. A<br />
value between that <strong>of</strong> diamond and silicon was assumed s<strong>in</strong>ce no <strong>the</strong>oretical value<br />
could be found <strong>in</strong> literature. A value <strong>of</strong> 0.055 was used. The values <strong>of</strong> diamond and<br />
silicon are ~ 0.01 and ~ 0.1 respectively and can be calculated by f<strong>in</strong>d<strong>in</strong>g <strong>the</strong> ratio <strong>of</strong><br />
<strong>the</strong> absorption length to that <strong>of</strong> <strong>the</strong> ext<strong>in</strong>ction distance which <strong>in</strong> turn could be found<br />
by various s<strong>of</strong>tware packages such as JEMS - Electron Microscopy S<strong>of</strong>tware.