90
4 Structural Defects
Fig. 4.28 Cross-sectional
TEM image showing
stacking faults in
heteroepitaxial GaAs on Si.
Adapted from [346]
Fig. 4.29 High resolution
TEM image of ZnS
nanowire exhibiting
periodical twin structures.
Adapted from [347]
Fig. 4.30 Reduced
stacking fault energy
(stacking fault energy per
bond) γ for various
compound semiconductors
plotted as a function of the
s-parameter. Dashed line is
guide to the eye. Data
from [185]
4.4.3 Grain Boundaries
The boundaries of crystal grains are called grain boundaries. They are defined by five parameters,
three rotation angles (e.g. Euler angles) to describe how the orientation of grain II results from grain I
and two parameters to define the boundary plane of the two grains in the coordinate system of reference
grain I.
Such defects can have a large impact on the electric properties. They can collect point defects and
impurities, act as barriers for transport (Sect. 8.3.8) or as carrier sinks due to (nonradiative) recombination. Details of their structure and properties can be found in [355, 356]. The two crystal grains
meet each other with a relative tilt and/or twist. The situation is shown schematically in Fig. 4.31a for
a small angle between the two crystals. A periodic pattern of dislocations forms at the interface that
is called a small-angle grain boundary (SAGB) (Fig. 4.31b). In Fig. 4.32, experimental results for pure
4 Structural Defects
Fig. 4.28 Cross-sectional
TEM image showing
stacking faults in
heteroepitaxial GaAs on Si.
Adapted from [346]
Fig. 4.29 High resolution
TEM image of ZnS
nanowire exhibiting
periodical twin structures.
Adapted from [347]
Fig. 4.30 Reduced
stacking fault energy
(stacking fault energy per
bond) γ for various
compound semiconductors
plotted as a function of the
s-parameter. Dashed line is
guide to the eye. Data
from [185]
4.4.3 Grain Boundaries
The boundaries of crystal grains are called grain boundaries. They are defined by five parameters,
three rotation angles (e.g. Euler angles) to describe how the orientation of grain II results from grain I
and two parameters to define the boundary plane of the two grains in the coordinate system of reference
grain I.
Such defects can have a large impact on the electric properties. They can collect point defects and
impurities, act as barriers for transport (Sect. 8.3.8) or as carrier sinks due to (nonradiative) recombination. Details of their structure and properties can be found in [355, 356]. The two crystal grains
meet each other with a relative tilt and/or twist. The situation is shown schematically in Fig. 4.31a for
a small angle between the two crystals. A periodic pattern of dislocations forms at the interface that
is called a small-angle grain boundary (SAGB) (Fig. 4.31b). In Fig. 4.32, experimental results for pure