Résumé:
The proposed topic in the context of this thesis focuses on the study, elaboration and characterization of pure zinc oxide (ZnO) thin films deposited on glass substrates by pyrolytic spraying technique mostly called SPRAY PYROLYSIS.
It's the effect of temperature and molarities on the physicochemical properties of ZnO thin films obtained by the spray process that interest us in this study.
Note that these deposits were developed at various temperatures (300 to 450°C) and molarities (0.05 to 0.4 M), using Zn (C2 H3 O2)2 • 2H2O an organometallic precursor.
The structural characterization by X-ray diffraction and Raman spectroscopy showed that the deposited films have a hexagonal polycrystalline wurtzite type structure whose
preferential crystallographic orientation is obtained according to the (100) plane.
Thus, we found an average crystallite size between 18 and 30 nm.
The optical characterization of the films was carried out using the UV-Visible spectroscopy in the spectral range from 200 to 800 nm. The results shows, that the transparence films are around 15 to 95%. The transmittance spectra analysis allowed us to determine the gap (3.16 to 3.3 eV) and the disorder of our estimated films (65.8 meV). These results are consistent with those obtained in the literature. We also conducted an electrical characterization of our samples by the four-point method. The deducted values of the pure zinc oxide electric conductivity are ranging from 8.15 to 80 (Ω.cm)
-1 at various temperatures and molarities. Thus, the deposited films have more conductive character for the deposit of ZnO in M=0.2 M and at 350°C.
In conclusion, the results show that films with low molarities (≤0,2 M) can be used as buffer layers in photovoltaic cells, while those with high molarities (˃0.2 M) are more promoters candidates for applications as gas sensors.
