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

structural rearrangement of the matrix, while the xed TO Si−N position indicates
the quality of the stochiometric layer desposited, within the sensitivity of the instrument.
In SRSN sample, annealing leads to an increase in the LO Si−N and TO Si−N
peak intensities accompanied with a shift towards higher wavenumbers. This could
be explained by the phase separation process in Si-rich material with annealing.
From the FTIR analysis, it can be seen that the structural properties of SRSN samples
depend only upon the composition (refractive index) and not on the deposition
approach.
(c) Raman spectroscopy
tel-00916300, version 1 - 10 Dec 2013
The Raman spectroscopy was performed on Si 3 N 4 and SRSN samples after annealing:
STA (1min-1000°C) and CA (1h-1100°C). The Raman spectra obtained on
these samples at dierent laser power densities ranging between 0.14-0.7 MW/cm 2
are shown in gures 4.12 and 4.13. The PL intensity of both the layers after STA
and CA annealing were also recorded in the Raman set-up at a higher laser power
density (1.4 MW/cm 2 ) and are shown in the inset. As mentioned in chapter 2, the
excitation wavelength is 532 nm (2.33 eV) corresponding to the green laser and Raman
shift of 0 cm −1 corresponds to 2.33 eV. The Stokes shift in eV is calculated from
the relative Raman shifts recorded, and is given in the upper scale of the gure.
Figure 4.12: Raman spectra obtained with dierent laser power densities from 1min-
1000°C and 1h-1100°C annealed Si 3 N 4 layers. The inset contains the corresponding PL
spectra [laser power density = 1.4 MW/cm 2 and λ excitation =532 nm (2.33 eV)] in the
Raman set-up.
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