Biomedical Engineering Reference
In-Depth Information
Fig. 1.15
10], (
b
)
[010], and (
c
) [1 1 0] crystallographic directions. The results after the deposition of 1.5 ML of
InAs at a substrate temperature of 500
◦
C without GaAs buffer layer growth are reported in (
d
-
f
).
The profiles on the AFM images for (
d1
), (
e
)and(
f
)areshownin(
g
-
i
), respectively. Adapted from
[
22
]. Copyright 2009 Institute of Physics
AFM topography images of initial oxide lines fabricated closely along (
a
)[1
−
crystallographic directions as shown in Fig.
1.15
a(1), b, c. The results obtained
after the deposition of 1.5 ML of InAs on samples without a GaAs buffer layer
show that a chain of 3D InAs nuclei is formed in the stripes closely aligned
along the [1 1 0] direction (see Fig.
1.15
f). In contrast, no clear evidence of InAs
nucleation is observed inside stripes aligned closely along the [1
10], and [010]
directions [Fig.
1.15
d(1), e, g, h]. Interestingly, only when the width of the pattern
stripealigned along the [1
−
1 0] direction is increased [from 120 to 160 nm, see
Fig.
1.15
a(2)], do isolated 3D nuclei appear leaning on their [1 1 0] sides [see
Fig.
1.15
d(2)]. The extension of B-type facets is clearly directly related with the
length of [1 1 0] sides in the nanoholes. These experimental results can be explained
if the In atom incorporation, under the growth conditions used, is clearly higher on
B-type facets (As-terminated) inside the patterned stripes. Therefore, by increasing
−
