Chemistry Reference
In-Depth Information
(a)
(b)
20 nm
4
00 nm
Fig. 10.16
(
a
) STM image of the GaSb nanodots grown at the substrate temperature of 200
◦
C.
(
b
) STM image of the sample after Ga and Sb with
∼
23 nm thickness were subsequently code-
posited at 200
◦
C and then, Ga and Sb with
71 nm thickness were codeposited at 450
◦
C
∼
this surface. Then, Ga and Sb with
71 nm thickness were further codeposited at
450
◦
C. Figure
10.16
b shows an STM image of the sample surface. The root mean
square roughness (
h
rms
)
∼
of the surface is about 4 nm, that is, very small compared
with that of the films grown by other methods [
39
-
41
]. RHEED patterns from this
surface revealed that the GaSb film epitaxially grew with the same crystallographic
orientations as those of the Si substrate.
Figure
10.17
shows a cross-sectional TEM images near the interface between
the grown GaSb film and Si(001) substrate. The white horizontal line in the image
indicates that the ultrathin SiO
2
film still remains at the interface. The inset is a
high-magnification TEM image of the square area. The lattice image reveals that
the strains caused by the lattice mismatch (
∼
.
2 %) are almost relaxed just at
the interface due to the ultrathin SiO
2
film. This result demonstrates a new tech-
nique to grow thin films on Si substrates even when the lattice mismatches are
large.
12
GaSb(001)
Si(001)
10 nm
Fig. 10.17
Cross-sectional TEM images near the interface between the GaSb film and Si(001)
substrate of the sample in Fig.
10.16
b. The
inset
is a high-magnification TEM lattice image of the
square area
