Chemistry Reference
In-Depth Information
10.3.2 Structures and Optical Properties of Ge Nanodots
in Si Films
Figure
10.3
shows scanning transmission electron microscope (STEM) dark-field
images of cross sections of Ge nanodots embedded in Si films on Si(001) substrates,
(a) as grown and (b) after annealing at 900
◦
C for 30min [
19
]. Ge nanodots have
bright contrast against Si films due to larger atomic number of Ge than that of Si.
Ge nanodots were formed in the Si(001) films for as-grown case, but decayed after
the annealing, forming thin film-like structures (Fig.
10.3
b).
Figure
10.4
shows annealing temperature dependence of photoluminescence
(PL) intensities at 4 K after 30-min annealing. The PL intensities became higher
in the energy region of
m wavelength) with the increase of the
annealing temperatures. This PL energy region is of practical importance for optical
fiber communication systems.
∼
0
.
8eV (
∼
1
.
5
μ
(a)
Si(001)
Si(001)
10 nm
(b)
Si(001)
Fig. 10.3
STEM images of
Ge nanodots embedded in Si
films: (
a
)Asgrownand
(
b
) after 900
◦
C-30min
annealing
50 nm
Si(001)
Fig. 10.4
Annealing temperature dependence of PL intensities at 4 K after 30-min annealing
