Biomedical Engineering Reference
In-Depth Information
g
a
d
9
6
3
0
200
400
600
Distance (nm)
b
e
h
9
6
3
0
200
400
600
Distance (nm)
c
f
i
9
6
3
0
150 nm
200
400
600
Distance (nm)
Fig. 1.17
AFM topography images of initial oxide dots with lateral dimensions 160 nm
×
160 nm
(
a
)
and
oxide
lines
fabricated
closely
along
[1 1 0]
direction
with
lateral
dimensions
160 nm
270 nm (
c
). The obtained results after deposition of 1.5 ML
of InAs on samples with a 7-nm-thick GaAs buffer layer growth are shown in (
d
-
f
). The profiles
along the lateral arrangement of QDs are depicted in (
g
-
i
). Adapted from [
22
]. Copyright 2009
Institute of Physics
×
230 nm (
b
) and 160 nm
×
samples (after oxide etching) without a GaAs buffer layer growth demonstrate that,
simply by varying the oxide size along the [1 1 0] direction from 160 to 270 nm,
an isolated QD (Fig.
1.16
d) or QDMs with two and three QDs in close proximity
(Fig.
1.16
e, f) can be obtained. These results are reproduced when a 7-nm-thick
GaAs buffer layer is grown. An isolated single QD (Fig.
1.17
d) is obtained for
the initial round shaped oxide dot (Fig.
1.17
a) and QDMs with two and three
QDs in close proximity (Fig.
1.17
e, f) for the initial oxide lines with lengths of
230 nm (Fig.
1.17
b) and 270 nm (Fig.
1.17
c) closely along the [1 1 0] direction. The
average peak-to-peak QDs distance in these QDMs is 54
3 nm, as measured on
the AFM profiles shown in Fig.
1.17
h, i. This separation is short enough to ensure
charge carrier interaction between the adjacent QDs as previously reported [
71
].
±
