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4 Structural Defects
(a)
(b)
(c)
(d)
Fig. 4.14 a High-resolution transmission electron microscopy image (HRTEM) in the 110 projection of a network of
misfit dislocations at a GaAs/CdTe/ZnTe interface. Substrate: GaAs (001), 2 ◦ off 110, ZnTe buffer layer is 2 monolayers
thick. b Fourier transform with round mask around the (111) Bragg reflection. (c) Phase and d amplitude images for the
mask from (b). From [321]
Since the energy of a dislocation is proportional to b
2 , only dislocations with the shortest Burger’s
vector are stable. The plane spanned by L and b is called the glide plane. In Fig. 4.14 a high-resolution
image of the atoms around a dislocation and the phase and amplitude of the (111) reflection are shown.
The phase corresponds to the atomic columns, the amplitude to the displacement of the atoms at the
dislocation core (see also Fig. 4.14).
4.3.1 Dislocation Types
4.3.1.1 Edge Dislocations
For an edge dislocation (Fig. 4.15a) b and L are perpendicular to each other. An extra half-plane
spanned by L and b × L is inserted.