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

emission intensity.
ˆ It is found that signicant PL intensities can be obtained by annealing under
forming gas at temperatures as low as 380-500°C during 0.5h.
4.12 Conclusion
tel-00916300, version 1 - 10 Dec 2013
A thorough investigation of SiN x materials indicated that the refractive index of
the layer is the most important indicator of the material properties. It is possible
to obtain similar structural and optical properties with the two kinds of deposition
approaches for silicon nitride layers investigated here (reactive sputtering and
co-sputtering). Signicant emission intensities were obtained by using SRSN in a
multilayer structure. A short time annealing treatment under nitrogen ow (STA,
1min-1000°C) on SRSO/SRSN MLs results in the highest emission intensities which
is attributed the high density Si-np. The presence of Si-np and therefore emission
after STA in SRSO/SRSN MLs contrary to SRSO/SiO 2 MLs reect the advantages
of SRSN in favouring the Si-np formation in SRSO sublayers with a faster kinetics.
Similarly, it is shown in this chapter that annealing under forming gas even at
low temperatures enhances emission intensity of the ML. Enhancing the emission
intensity of the SRSO/SRSN MLs either by STA or by FG annealing reects the
advantages of this material over SRSO/SiO 2 which requires 1h-900-1100°C for Si-np
formation leading to emission, with regard to thermal budget for photovoltaics or
even photonic applications. The density of Si-np after STA in SRSO/SRSN ML (almost
10 20 np/cm 3 ) is higher than the Si-np density achieved after CA in SRSO/SiO 2
ML.
Hence, a preliminary experiment to test these two samples for electrical conductivity
was made. Figure 4.46 compares the dark current curves of (3.5 nm SRSO/5
nm SRSN) with our (3.5 nm SRSO/3.5 nm SiO 2 ) MLs.
The resistivity was calculated to be 2.15 and 214 MW·cm in the SRSO/SRSN and
SRSO/SiO 2 MLs, respectively at 7.5 V. Since the thickness of the SRSO sublayer is
the same in both cases (3.5 nm), this decrease in the resistivity of the SRSO/SRSN
MLs can be ascribed to the substitution of SiO 2 by SRSN sublayers. This two-fold
enhanced conductivity paves the way for further improvement of the SRSO/SRSN
MLs' conductivity, for example, by decreasing the thickness of this SRSN sublayer.
Thus, this chapter successfully demonstrates the advantages of SRSO/SRSN over
SRSO/SiO 2 MLs with a control over thermal budget for device applications.
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