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

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Fig. 5.2 A schematic diagram of the fault on the (111) planning assuming that it has
nucleated at point O. W1 and W2 are the widths of the fault on the top and bottom of
the foil respectively.
(e) The last possibility is that stacking faults arise during the growth of the film due to
incorrect deposition of some nuclei on the surface of the growing film. This could be
as a result of a rapid deposition rate, inhomogeneities in the film or impurities in the
carrier gas. Furthermore diffusion rates in SiC are very low at the temperature of
deposition and thus the nuclei would not have enough time to readjust themselves to
the correct position. Once a mismatch boundary has formed stacking faults will grow
on the {111} faces with further growth of the film. A schematic illustration of this is
given in Fig. 5.2. It is assumed the stacking fault nucleated at point O due to some
inhomogeneity and grow wider as the layer thickened in the [001] direction. Since the
directions are parallel to the Peierls valleys in crystals with sphalerite structure,
and the Peierls energy is expected to be very high in SiC, the growth occurs such that
the partials bounding the stacking fault lie along these directions. Measuring the width
of the fault at the top of the foil, W1 enables one to determine the depth below the
surface, h, at which the stacking fault nucleated,
h W1
/
2
Yun et al. (2006) explained that the stacking fault formation is a result of a large
number of twins forming on {111} planes during the early stages of growth prior to
the coalescence of nuclei. The atomic stacking errors may form on {111} planes of