Study of post annealing influence on structural, chemical and electrical properties of ZTO thin films

Research highlights: → Structural, chemical and electrical properties of cost effective ZTO thin films with varying concentrations. → Effect of annealing of ZTO films. - Abstract: Zinc-Tin-Oxide (ZTO) thin films were deposited on glass substrate with varying concentrations (ZnO:SnO2; 100:0, 90:10, 70:30 and 50:50 wt.%) at room temperature by flash evaporation technique. These deposited ZTO films were annealed at 450 deg. C in vacuum. These films were characterized to study the effect of annealing and addition of SnO2 concentration on the structural, chemical and electrical properties. The XRD analysis indicates that crystallization of the ZTO films strongly depends on the concentration of SnO2 and post annealing where annealed films showed polycrystalline nature. Atomic force microscopy (AFM) images manifest the surface morphology of these ZTO thin films. The XPS core level spectra of Zn(2p), O(1s) and Sn(3d) have been deconvoluted into their Gaussian component to evaluate the chemical changes, while valence band spectra reveal the electronic structures of these films. A small shift in Zn(2p) and Sn(3d) core level towards higher binding energy and O(1s) core level towards lower binding energy have been observed. The minimum electrical resistivity (ρ ∼ 3.69 x 10-2 Ω-cm), maximum carrier concentration (n ∼ 3.26 x 1019 cm-3) and Hall mobility (μ ∼ 5.2 cm2 v-1 s-1) were obtained for as-prepared ZTO (50:50) film thereafter move towards lowest resistivity (ρ ∼ 1.12 x 10-3 Ω-cm), highest carrier concentration (n ∼ 2.96 x 1020 cm-3) and mobility (μ ∼ 18.8 cm2 v-1 s-1) for annealed ZTO (50:50) thin film.