The effect of annealing in nitrogen atmosphere on the structure, photoluminescence and electrical properties of Li and Cu doped sol-gel ZnO films

The effect of annealing in air and in nitrogen atmosphere on the structure, luminescence emission and electrical properties of ZnO, Li:ZnO and Cu:ZnO doped thin films prepared by sol-gel method was investigated by scanning electron microscopy, X-ray diffraction, photoluminescence and resistivity measurements. The films annealed in nitrogen demonstrate smoother surfaces, improved crystallinity and conductivity. The residual stress in doped films changes from tensile type, when annealed in air, to compressive type in the case of annealing in nitrogen atmosphere. The effect is associated with the density of lattice defects in the films annealed in nitrogen.