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

(a) σ emis.max. = 8.78 x 10 −18 m 2 (b) σ emis.max. = 8.78 x 10 −17 m 2
Figure 5.21: Simulating the width and intensity of PL spectra similar to experimental
curve using single emitter and higher emission cross-sections.
tel-00916300, version 1 - 10 Dec 2013
by increasing the emission cross-section or by decreasing the input widths. However
in all these cases, the width of the theoretical spectra is lower than the experimental
one, and all the curves can be tted with a single peak. These results suggest that
the presence of another peak (peak 1) is not from interference or any other optical
eects.
(c) Photoluminescence from double kind of emitters in multilayer conguration
In order to conrm the presence of two peaks to be a contribution from two kinds
of emitters, simulations were performed using two emitters leading to two peaks
at 1.4 and 1.5 eV in the input. Several trials were made by varying the emission
cross-section parameters (see Eqn. 5.36), few of which are shown in gure 5.22a.
The details of the six trials represented in this gure are given in Appendix 2. It
can be seen that the intensity and width of the theoretically obtained spectra from
few of the trials appear to match well with the experimental one. The PL spectra
from trial 3, was chosen for further analysis (Fig. 5.22b).
The inset of gure 5.22b shows a lorentzian curve t performed on the trial 3
simulated curve (obtained with σ em.max = 8.78 x 10 −17 m 2 for both kinds of emitters,
emission peak centers for the two emitters at 1.55 eV and 1.38 eV, with widths 0.29 eV
and 0.14 eV respectively). The results indicate that the broad peak of the simulated
PL curve can be tted with two peaks with positions and width similar to that
of the experimentally obtained one. This tting operation is not straight-forward,
since the thin lm acts as an optical cavity that lters the spectral distribution of
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