Transparent  and semi transparent conductive Al-doped ZnO (AZO) thin films were electrodeposited on indium doped tin oxide(ITO)coated glass substrates from aqueous mixed bath of zinc nitrate and potassium chloride with  2%,4%,6%,8% of Al(NO₃)₃ as doping  at 70°C using chronoamperometry technique. Thin and adherent films were obtained after same deposited time of 60min and under different applied potentials (-1V/ Ag/AgCl)  chosen. The structural properties have been performed using X ray diffraction which showed that all obtained AZO thin films present wurtzite phase with highly c-axis preferred orientation. AZO films with 4%, 6% and 8% exhibit other weak peaks with other orientations (101) and (100) suggesting that those later AZO films are polycrystalline. Generally crystallites sizes calculated using Deby Sherrer formulae decreased with the enhancement of doping concentration.

The presence of compression stress plays critical role in determining the crystalline structure of AZO films, which tends to stretch the lattice constant c and enlarge the (002) diffraction angle. Sample obtained with large amount of doping 8% of Al³⁺ exhibit a compressive stress (ε < 0) parallel to the growth plane (002).

The morphological characterization of the pure and doped deposits was carried out by MEB whereas the optical characterization was realized by UV-visible spectroscopy.

Indeed, it was noted that the increase in the concentration of the doping agent supports promotes growth in transmitance of deposits and a variation of the gap. In parallel one observed by MEB a specific growth of structure in the form of nanorods which differs from the morphology of pure ZnO. It is also alternative with the concentration of the doping agent.

References

[1] H. Chettah, D. Abdi, Thin Solid Films 537 (2013) 119.

[2] T. Frade, M.E. Melo Jorge, A. Gomes, Mater. Lett. 82 (2012) 13.

[3] H. Chettah, D. Abdi, H. Amardjia, H. Haffar, Ionics 15 (2) (2009) 169.