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

The trends of Si excess with r H from FTIR is not well dened, but from results
deduced from ellipsometry one can notice an increase in the formation of Si-np.
3.3 Co-Sputtering- Method 2
tel-00916300, version 1 - 10 Dec 2013
In order to improve r d and n 1.95eV obtained by reactive sputtering, another method
of incorporating Si excess into the SiO 2 matrix was adopted. This method involves
co-sputtering of the Si and SiO 2 targets in a pure Ar plasma at T d =500°C.
The power density applied on the Si cathode was varied to see the inuence on
deposition rates, refractive index and structural changes. The power density of Si
can be altered by changing the percentage of the power applied on the Si target
with regard to the total power (= 300 W) in the experimental set-up. As before,
the power density of SiO 2 was xed at 7.4 W/cm 2 while power densities of Si were
varied between 1.62 to 2.96 W/cm 2 .
3.3.1 Deposition rate (r d ) and Refractive Index (n 1.95eV )
All the SRSO samples were grown with a xed deposition time of 3600s. The
inuence of increasing P Si on r d and n 1.95eV is represented in gures 3.7a and 3.7b.
The inset shows the thickness variations with increasing P Si .
(a) Deposition rate.
(b) Refractive index.
Figure 3.7: Eect of P Si on (a) Deposition rate (r d nm/s); (inset) the thicknesses, and
(b) Refractive index (n 1.95eV ).
The thickness, deposition rate as well as the refractive index increase with increasing
P Si . Since there is no etching mechanisms due to the absence of hydrogen
in this approach, there is an increase of the deposition rate and thickness with P Si .
Besides, the increase of Si power density favours the incorporation of Si excess in
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