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

tel-00916300, version 1 - 10 Dec 2013
Figure 3.16: Summary of r d (nm/s) and n 1.95eV obtained with the three SRSO sputtering
growth methods.
ˆ FTIR spectra reveals the presence of a peak around 1107 cm −1 in samples
with high Si excess. This is suggested to be he formation of interstitial oxygen
within Si core during reorganization.
ˆ An annealing at 1100°C during 1h is considered as the best condition for the
formation of nanocrystals as conrmed by Raman and XRD spectra.
ˆ Absence of visible emission from higher refractive index SRSO samples is related
to the high Si excess.
ˆ High absorption coecient curves are obtained even with as-grown SRSO samples
grown by reactive co-sputtering.
ˆ To avoid the formation of bigger nanocrystals due to a very high Si excess
within SRSO sublayer, a middle value of P Si =2.22 W/cm 2 is chosen to be
used for multilayer structures.
3.6 Role of the Hydrogen plasma
As seen from all the discussions above, there is a competition between etching and
deposition due to hydrogen in the plasma. Therefore, before proceeding with investigations
on multilayers, it becomes interesting to see the role of hydrogen plasma
towards deposition. In order to compare its role during the deposition and after the
deposition processes, a sample was merely placed in the hydrogen plasma by closing
the shutter on the targets to avoid sputtering.
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