Abstract:
This work is devoted to the development of the tin oxide thin films by the sol-gel
method. The effect of the annealing temperature, the number of layers and the doping on the
structural and optical properties of the films obtained were investigated. The obtained films
are characterized by X-ray diffraction (DRX), RAMAN spectroscopy, atomic force
microscopy (AFM), UV-Visible spectroscopy and ellipsometry spectroscopic.
Raman spectroscopy results show that the SnO2 thin films are crystallizes in rutile
phase. A good crystallization is observed after 3 coats. The results of optical characterization
show that all the films are transparent (75 to 85% optical transmittance) in the visible and The
energy band gap of all the samples lies in the range of 3.63eV– 3.89eV
With regard to doping, undoped and doped tin oxide thin films (SnO2:Cd, SnO2:Al)
were deposited by Sol Gel Dip Coating method on glass and silicon Si(100) substrates. The
DRX shows that all the films deposited on glass substrates have an amorphous structure. On
the other hand, the films deposited on Si (100) substrate crystallize in the rutile phase, with a
preferential orientation along the axis (310). AFM observations of the surface show that the
doping rate affects the roughness. The grain size and the roughness of the samples decrease
with the increase of the doping concentration. The SnO2, SnO2:Cd and SnO2:Al thin films are
transparent in the visible region and opaque in the ultraviolet region. The band gap,
determined from the transmission spectra for the deposited films, also decreases with the
increase in the doping rate (from 06 to 10% Cd, and from 04 to 06% Al). In addition, the
increase of the cadmium and aluminum doping concentration causes a slight increase in the
refractive index.
