84
4 Structural Defects
L
(b)
(c)
(a)
[110]
=60°
=90°
=0°
(d)
b
L
Fig. 4.17 Dislocations in the zincblende structure. The line vector is along [100]. The Burger’s vector a/2 110 can
create an a edge dislocation, a b screw dislocation, and c a 60 ◦ dislocation. d Atomistic structure of a 60 ◦ dislocation
(a)
(b)
Fig. 4.18 a Plan-view transmission electron microscopy image of a network of 110 dislocation lines in (In,Ga)As
on InP (001) with a lattice mismatch of about 0.1%. The TEM diffraction vector is g = [2 ¯
20]. Adapted from [323]. b
Panchromatic cathodoluminescence image of partially relaxed Al 0.13 Ga 0.87 N on (30 ¯
31) GaN heterostructure with inplane directions indicated. Adapted from [324], reprinted under a Creative Commons Attribution (CC BY 3.0) unported
licence
4.3.1.4 Misfit Dislocations
When materials with different lattice constants are grown on top of each other, the strain can plastically
relax via the formation of misfit dislocations. A typical network of such dislocations is shown in
Fig. 4.18a for (In,Ga)As on InP (001). Another example is given in Fig. 4.18b for the (Al,Ga)N/GaN
system on a semipolar (30 ¯
31) lattice plane tilted to the c-axis. This leads to non-rectangular dislocation
directions which are universal for dislocations from glide on a- and m-planes in heterostructures of
trigonal and hexagonal materials [325] (Fig. 4.19).
4.3.1.5 Partial Dislocations
Partial dislocations, i.e. the Burger’s vector is not a lattice vector, must necessarily border a twodimensional defect, usually a stacking fault (Sect. 4.4.2). A typical partial dislocation in diamond or
zincblende material is the Shockley partial dislocation (or just Shockley partial) with Burger’s vector
b = (a 0 /6) 112. Another important partial is the Frank partial with b = (a 0 /3) 111. A perfect
4 Structural Defects
L
(b)
(c)
(a)
[110]
=60°
=90°
=0°
(d)
b
L
Fig. 4.17 Dislocations in the zincblende structure. The line vector is along [100]. The Burger’s vector a/2 110 can
create an a edge dislocation, a b screw dislocation, and c a 60 ◦ dislocation. d Atomistic structure of a 60 ◦ dislocation
(a)
(b)
Fig. 4.18 a Plan-view transmission electron microscopy image of a network of 110 dislocation lines in (In,Ga)As
on InP (001) with a lattice mismatch of about 0.1%. The TEM diffraction vector is g = [2 ¯
20]. Adapted from [323]. b
Panchromatic cathodoluminescence image of partially relaxed Al 0.13 Ga 0.87 N on (30 ¯
31) GaN heterostructure with inplane directions indicated. Adapted from [324], reprinted under a Creative Commons Attribution (CC BY 3.0) unported
licence
4.3.1.4 Misfit Dislocations
When materials with different lattice constants are grown on top of each other, the strain can plastically
relax via the formation of misfit dislocations. A typical network of such dislocations is shown in
Fig. 4.18a for (In,Ga)As on InP (001). Another example is given in Fig. 4.18b for the (Al,Ga)N/GaN
system on a semipolar (30 ¯
31) lattice plane tilted to the c-axis. This leads to non-rectangular dislocation
directions which are universal for dislocations from glide on a- and m-planes in heterostructures of
trigonal and hexagonal materials [325] (Fig. 4.19).
4.3.1.5 Partial Dislocations
Partial dislocations, i.e. the Burger’s vector is not a lattice vector, must necessarily border a twodimensional defect, usually a stacking fault (Sect. 4.4.2). A typical partial dislocation in diamond or
zincblende material is the Shockley partial dislocation (or just Shockley partial) with Burger’s vector
b = (a 0 /6) 112. Another important partial is the Frank partial with b = (a 0 /3) 111. A perfect