M. Rouchdi

SYNTHESIS AND MAGNETIC PROPERTIES OF Ni-DOPED ZnO THIN FILMS: EXPERIMENTAL AND AB INITIO STUDY

Structural and magnetic properties of Zn1−xNixO thin films and diluted magnetic semiconductors have been investigated. This sample has been synthesized using a spray pyrolysis technique with a stoechiometric mixture of zinc acetate (C4H6O4Zn⋅2H2O) and Nickel acetate (C4H6O4Ni⋅ 2H2O) on a heated glass substrate at 450∘C. The films were characterized by X-ray diffraction (XRD), UV–Vis spectrophotometry and Hall Effect measurements. These films of ZnO crystallized in the hexagonal Wurtzite structure. The optical study showed that the band-gap energy was increased, from 3.3eV to 3.5eV, with increasing the Ni concentration. The film resistivity was affected by Ni-doping, and the best resistivity value 1.15×10−2 (Ω cm) was obtained for the film doped with 2 at.% Ni. The electronic structure and optical properties of the Wurtzite structure Zn1−xNixO were obtained by first-principles calculations using the Korringa–Kohn–Rostoker method combined with the coherent potential approximation (CPA), as well as CPA confirm our results.

Effects of sulfur concentration on structural, optical and electrical properties of Tin Oxide thin films deposited by spray pyrolysis technique

Thin films of Tin oxide doped with deferent concentration of Sulfur were prepared on glass substrates at 400 °C by spray pyrolysis technique. The thin films were characterized to study their physical properties. Effects of Sulfur concentration on structural, optical and electrical properties of transparent Tin Oxide thin films were investigated in the Sulfur content range (0–10) at%. It was observed from X-ray diffraction patterns (XRD) that the films have a polycrystalline structure and the intensity of the peaks depends on the doping content. No diffraction peak related to dopants in XRD patterns along with a shift in peaks angles to SnO<inf>2</inf> proved that S ions were doped into SnO<inf>2</inf> thin films and the size of the grains has been changed from 3.7 to 4.1 nm. The optical gap of Sn<inf>1−x</inf>S<inf>x</inf>O<inf>2</inf> thin films was determined to be about 2.58 to 3.63 eV. From the Hall Effect measurements, the minimum resistivity 6.34×10⁻² (Ω.cm) was obtained from S-doped SnO<inf>2</inf> (5 at. %).

Effect of Gd doping and (Gd, Li) co-doping ZnO thin films on optical properties: Experimental and ab-initio study

The ZnO thin films were deposited by spray pyrolysis technique on glass substrate heated at 450° C, using as source zinc acetate with a molar concentration of 0.05 mol/l. Our interest is to study in some details the effect of doping Gd:ZnO (GZO) and co-doping Gd,Li:ZnO (GLZO) on optical properties. For this, we have used the optical UV-Visible spectroscopy to determine the band gap energy of the samples. Optical analysis revealed that the band gap energy increases, from 3.20 to 3.23 eV, with increasing the Gd concentration and increases for co-doped ZnO (Gd,2% Li) as compared to Gd doped ZnO from 3.23 to 3.25 eV. The electronic structure and optical properties of the Wurtzite structure Zn1−x−yGdxLiyO were obtained by ab-initio calculations using the Korringa-Kohn-Rostoker method (KKR) combined with the Coherent Potential Approximation (CPA), as well as Coherent Potential Approximation (CPA) confirms our results.