Defect structure and conductivity mechanisms in nanostructured oxide films obtained by spray pyrolysis method

Abstract

The defect structure and electronic conductivity mechanisms in nanostructured films of transparent conducting oxides ZnO and SnO₂ obtained by spray pyrolysis were investigated. Using electron paramagnetic resonance (EPR), photoluminescence (PL) spectroscopy, and temperature-dependent electrical conductivity measurements, the main types of defects were identified, and their influence on transport properties was analyzed. It has been established that the film conductivity is determined by a combination of processes: intragrain electron transport through the conduction band, tunneling through potential barriers at grain boundaries, and thermally activated conductivity through defect states. The paper proposes a new conductivity model that takes into account the morphological features of nanostructured films and the energy distribution of defect states. It is shown that oxygen vacancies VO and interstitial zinc atoms Zni are the main donor centers in ZnO, while oxygen vacancies and impurity atoms dominate in SnO₂. The developed model allows predicting the electrical properties of oxide films depending on synthesis conditions and can be used to optimize technological parameters for obtaining transparent conducting coatings.