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

the penetration of X-rays into the substrate is minimized and a large volume of the
thin lm can be investigated by increasing the X-ray path. Hence, Bragg's peaks
arise only from the surface structure. The Cu X-rays generated by the X-ray tube
are collimated and directed on the sample. The intensity of the diracted X-rays
are recorded. The grazing angle of incidence is xed at ω = θ= 0.5° and the angle
between the incident beam and the detector varies between from 2θ =10°-90°.
Informations extracted in this thesis
ˆ The amorphous or crystalline natures of the thin lms are investigated from
the absence/presence of the diraction peaks.
tel-00916300, version 1 - 10 Dec 2013
ˆ An estimation of crystalline volume in the material can be obtained. Figure
2.8 shows a typical spectrum obtained from a Si-based multilayer with the
diraction peaks (hkl) corresponding to (111), (220) and (311) planes of Si
nanocrystals.
Figure 2.8: A typical example of XRD spectrum taken from Si-based multilayer containing
Si nanocrystals.
ˆ In some cases, the grain size of crystalline volume from the diraction peak
corresponding to Si (111) plane was estimated using the Scherrer's formula,
Grain size = (Kλ)/(βcosθ) Eqn (2.5)
where K (= 0.9) is a constant known as the shape factor, λ (=1.5406 angström)
is the wavelength of X-ray, θ is the Bragg's diraction angle converted to
radians and β is the full width at half maximum of the diraction peak under
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