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

and the intensity is gradually decreased for all other t A . It has to be noticed that
for annealing time longer than 1min, the three peak structure disappears. As in
the previous case, the shift of the peak (2) with respect to the as-grown sample can
be ascribed to the growth of Si-np. The observed decrease of PL intensity for time
higher than 1min can be explained in the same way as that in the case of 700 °C.
4.6.4 T A =1000°C:
Figure 4.31 shows the PL spectra and the peak positions of 100(3.5/5) MLs annealed
at 1000°C.
tel-00916300, version 1 - 10 Dec 2013
sample peak 1
(eV)
peak 2
(eV)
peak 3
(eV)
as grown 1.41 1.62 1.88
1min 1.50 1.53 1.85
Figure 4.31: PL spectra of 100(3.5/5) ML annealed at 1000°C. The peak positions obtained
after gaussian tting are indicated in the table.
The behaviour at 1000°C follows a similar trend as the previous case but is more
pronounced, with 1min-1000°C (STA) showing the highest intensity followed by a
quenching of PL when t A is long. This behaviour is already explained in the section
above.
4.6.5 Inuence of short time and long time annealing on emission
It can be noticed from previous discussions that the emission intensities from samples
annealed during 1min-1000°C (STA) and 16min-700°C are similar. Considering the
thermal budget and the maximum emission intensities, STA can be considered as
the best annealing treatment from the analyses done above. In order to witness a
possible enhancement of the emission intensity in these MLs with thermal budget,
higher temperatures were employed for t A = 1min. Figure 4.32a consolidates the
PL intensities obtained from all the samples subjected to 1min annealing between
400°-1100°C.
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