Geoscience Reference
In-Depth Information
Table 5.2 Dislocation Density in Different Seeds
Seed
Mineralizer
Etch Channel Density
Z
Hydroxide
253
Z
Carbonate
247
X
1
Hydroxide
1
X
1
(reused)
Hydroxide
14
Figure 5.6 Dislocation density
in quartz
[34]
.
Figure 5.7 Dislocation density
in quartz
[34]
.
that, when a seed perpendicular to the Z-axis (but from the X-growth region) is used,
the dislocation density can be reduced to below 10, and sometimes to 0 dislocations
per square centimeter (
Table 5.2
;
Figures 5.6 and 5.7
). Although the reasons for this
are not entirely understood, it may be related to the fact that, unlike dislocations in
the Z-region where they form at the seed and grow close to the Z-axis, most disloca-
tions in the X-region grow at an angle of at least 45
and are usually close to 90
from the Z-axis. Studies have shown that aluminum in the seed does not migrate into
the growth regions. Thus, the purity of the crystals produced using seeds cut from
the X-region is as good as crystals produced from the usual Z-seed.
