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

Ray Diraction, X-Ray Reectivity, Electron Microscopy, Raman spectroscopy, ellipsometry,
photoluminescence spectroscopy. An insight on the structural and compositional
details of the as-deposited and the annealed lms can be extracted from
microscopic images, characteristic vibrational frequencies of specic elements in the
lm, refractive indices, the material's absorption and emission behaviours etc., resulting
from the above mentioned characterization techniques.
2.2.1 Fourier Transform Infrared Spectroscopy (FTIR)
Principle
tel-00916300, version 1 - 10 Dec 2013
FTIR spectroscopy is a powerful tool to investigate the chemical bonds present in a
molecule. Molecular bonds vibrate at specic frequencies depending on the elements
and the types of bond they possess. When the incident IR light interacts with the
molecules, they absorb light at these specic frequencies that are characteristic of
their structure. The molecules can vibrate in any of the following ways: symmetrical
and asymmetrical stretching, scissoring, rocking, wagging and twisting as indicated
in gure 2.3. The resulting absorption spectrum yields both qualitative as well
as quantitative information on the chemical bonds and their concentration in the
material, respectively.
Figure 2.3: Dierent types of molecular vibrations.
Experimental set-up and working
FTIR measurements were performed using Thermo Nicolet Nexus 750-II. The spectra
were recorded in wavelength ranging between 400 to 4000 cm −1 with a resolution
of 2 cm −1 at room temperature. The apparatus has two light sources: He-Ne
monochromator (633 nm) and a lamp with tungsten lament that generates light
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