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

tion but within a dierence of one order of magnitude. It can also be seen that at
high energies, the level of absorption in SRSO/SRSN ML approaches that of Si. This
shows that the replacement of SiO 2 by SRSN sublayers in ML favours absorption.
Despite a higher pump absorption in CA SRSO/SRSN ML, in comparison to
SRSO/SiO 2 ML, there is a quenching of PL from the former. This implies that CA
SRSO/SRSN ML favours absorption but has a detrimental eect on emission.
4.6 Eect of annealing treatment under N 2 ow
tel-00916300, version 1 - 10 Dec 2013
It was seen in the previous sections that the SRSO/SRSN samples contain nanocrystals
as SRSO/SiO 2 MLs, but the presence of SRSN sublayers create a detrimental
eect on the PL emission after CA. However, both the as grown (not shown) and
CA SRSO/SRSN MLs have high α values. These results indicate the possibility of
intermediate annealing treatments that might favour PL emission. A detailed investigation
on the eect of annealing treatments (temperature and time) was made
to optimize the PL emission.
Annealing steps
1min
1+15min
1+15+15min
1+15+15+30min
1h continuous annealing
Denoted as
1min (1min
1000°C-STA)
16min
31min
61min
LTA
(1h-1100°C-CA)
Figure 4.27: Pictorial representation of step by step annealing under N 2 ow. (Table)
Details of annealing time used for investigation and their notations.
The 100(3.5/5) ML was annealed at various temperatures (T A ) between 400°-
1100°C while the time of annealing (t A ) was varied between 1 minute to 61 minutes
in steps as can be seen in the pictorial representation of gure 4.27. Continuous
Long Time Annealing (LTA) of 1 hour at various temperatures were also performed.
The emission obtained from LTA MLs were compared with MLs annealed for 61
minutes in steps. Table of gure 4.27 details the various annealing steps employed
for these investigations and the way they are denoted in the forthcoming parts. The
eect of T A and t A on the emission intensities of SRSO/SRSN ML are discussed
below. (All the graphs in the discussions that follow in this section are comparable).
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