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

Figure 2.12: Raman spectrometer-Schematic representation.
tel-00916300, version 1 - 10 Dec 2013
laser was used for measurements on some of the ML samples deposited on a quartz
substrate, in order to avoid the confusions between Si contribution from the sample
and the Si substrate that has a peak around 521 cm −1 . The laser beam at 532 nm
was incident on the sample, and most of the measurements were performed with a
low power density of 0.14 MW/cm 2 in order to avoid any inuence of laser heating.
Few measurements were also performed by varying the power densities between 0.14-
1.4 MW/cm 2 to see if there were any laser induced annealing on the microstructure
of the sample. Figure 2.13 shows a typical Raman spectra obtained from Si and
fused silica substrates.
(a) Si monocrystalline substrate
(b) Fused silica substrate.
Figure 2.13: Typical Raman spectra of the substrates used in this thesis.
Informations extracted in this thesis
ˆ The peak intensity gives information on the volume of crystalline phase of Si.
ˆ The shift of the baseline at higher wavenumbers in the Raman spectra is
indicative of photoluminescence.
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