Abstract:
The aim of this thesis work consists in the improvement of ZnO’s structural, electrical and optical properties for humidity
analysis. The preparation of undoped ZnO thin films doped ZnO with Aluminium and Mercury and codoped ZnO with Aluminium/
Mercury on glass and silicon substrates was performed by sol gel method (dip coating). The obtained ZnO thin films were
characterized by various characterization techniques.
The structural characterization RX diffraction performed on our samples shows that all these films have a hexagonal structure
(wurtzite). The changing of the solvent, the variation of the concentration and the withdrawal speed, have an important influence
on the undoped ZnO thin films structural (SEM and AFM) and optical (UV-visible and Photoluminescence) properties. The results
indicate that a better sensitivity and a fast response time were obtained by using the 2-Methoxyethanol as a solvent. The Aluminium
doping at 800°C heat treatment allowed us first to ameliorate the structural, electrical and optical properties and second to have a
better sensitivity for humidity sensing.
The mercury doping participates in the appearance of the cubic shapes which has immense influence on the surface roughness.
The obtained thin films have a good transparency in the visible range whereas the energy band gap depends on the doping rate, the
resistivity vary in proportion to the doping rate. The codoping of aluminium to mercury allowed us also to improve the structural,
electrical and optical properties especially the electrical conductivity.
