Vacuum annealing effect on physical properties and electrical circuit model of ZnO:Sn/SnO2:F bilayer structure

Abstract

Tin doped Zinc oxide/Fluorine doped tin dioxide bilayer films (ZnO:Sn/SnO2:F) were deposited on glass substrates using spray pyrolysis technique. The effect of vacuum annealing at different temperatures was investigated. Both structural and morphological analysis have shown that there is a significant modification in the bilayer film structure and surface following the vacuum annealing process at 450 °C. Electrical properties have been investigated using the Hall Effect measurements as well as the impedance spectroscopy at room temperature. The circuit parameters were determined using an equivalent circuit model fitted from the impedance spectra and suggesting the presence of grain and grain boundary conductions in the bilayer structure. It was found that the film annealed in vacuum for 1 h at 350 °C is optimal in all respects, as it possesses all the desirable characteristics including the lowest resistivity, high porosity and better grain boundary conductivity