Films minces à base de Si nanostructuré pour des cellules ...

4.6.1 T A =400°C:
Figure 4.28 shows the PL spectra of SRSO/SRSN MLs annealed at 400 °C and their
peak positions with respect to various time steps of annealing.
sample peak 1
(eV)
peak 2
(eV)
peak 3
(eV)
as grown 1.41 1.62 1.88
1min 1.46 1.62 1.95
16min 1.41 1.62 1.91
31min 1.40 1.62 1.86
61min 1.38 1.62 1.87
tel-00916300, version 1 - 10 Dec 2013
Figure 4.28: PL spectra of 100(3.5/5) ML annealed at 400°C. The peak positions obtained
after gaussian tting are indicated in the table.
The three peaks obtained after gaussian tting are indicated as peak (1), (2) and
(3) in the gure and the table. It can be seen from the spectra that the emission
intensity of all the three peaks increase with t A . About twofold increase in the
emission intensity is observed from the sample annealed at highest t A as compared
to the as-grown sample while the position of peak (2) is always centered at 1.6 eV.
The shifts in the peak positions of (1) and (3) are not signicant since their maxima
are not well dened.
The increase in all the three peak intensities with annealing time may indicate a
beginning of reorganization of the matrix and a decrease of the non-radiative defects.
The xed position of peak (2) indicates that there is no modication of Si-np size
with increasing t A due to the low annealing temperature applied here.
4.6.2 T A =700°C:
Figure 4.29 shows the PL spectra and the peak positions of 100(3.5/5) ML annealed
at 700°C.
The presence of three peaks is witnessed at all t A at this temperature also.
Contrary to the previous case, the PL intensity increases only till 16min and then
starts to decrease with longer t A . The previous comment on the shifted peak is
still valid for peaks (1) and (3). Concerning the peak (2), its maximum being well
dened, the shift is signicant as a function of the annealing time. It can be seen
that peak (2) is redshifted after 16min of annealing as compared to the as-grown
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