Cathodoluminescence emission study of nanocrystalline indium oxide films deposited by spray pyrolysis

The results of analysis of In2O3 film cathodoluminescence (CL) spectra are presented in this paper. In2O3 films, aimed for gas sensor application, were deposited by spray pyrolysis from 0.2 M InCl3–water solutions. The influence of grain size (10–60 nm), film thickness (20–400 nm), pyrolysis temperature (Tpyr = 400–520 °C), and annealing in the air or nitrogen atmospheres (Tan = 600–1100 °C) on CL emission of In2O3 is discussed.CL spectra of as-deposited In2O3 films were characterized by a broad band centered at λ ∼ 570–600 nm. The annealing of studied films leads to a considerable increase of CL intensity. High annealing temperature of In2O3 films (Tan > 850 °C) is being accompanied by the appearance of additional bands centered at λ ∼ 400, 550, and 650 nm, which are peculiar to single-crystalline In2O3 nanobelts, or nanowires with perfect crystal structure. It was concluded that the improvement of crystal structure and the decrease of the concentration of oxygen vacancies are the main factors determining the change of CL spectra of In2O3 films and the appearance of edge luminescence.