Biomedical Engineering Reference
In-Depth Information
FIGURE 15.3
Cross-sectional SEM of a distributed Bragg reflector
[17]
, consisting of alternate layers of very different
CTFs, which have different porosities and different effective permittivity tensors.
comprise upright nanocolumns, whereas the
CTFs grown with a highly oblique vapor flux
are highly porous and comprise tilted
nanocolumns. As a result, their effective
permittivity tensors are very different, and the
periodic stacking of the two types of CTFs leads
to the exhibition of the Bragg phenomenon.
15.2.6 Conformal-Evaporated-Film-by-
Rotation Technique
The
conformal-evaporated-film-by-rotation
(CEFR)
technique allows fabrication of high-fidelity rep-
licas of biotemplates with micro- and nanoscale
features distributed over planar and curved
surfaces
[18, 19]
. In the CEFR technique, the
template is mounted on a substrate holder that
is rotated rapidly about its central normal axis
while the OAD technique is being implemented
to coat the exposed surface of the template with
a thin film. The vapor flux angle
χ
v
is fixed in the
neighborhood of 5°, as shown schematically in
Figure 15.4
. After the coating of thickness about
FIGURE 15.4
Schematic of the CEFR technique.
