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

Abstract The results of analysis of In 2 O 3 film cathodoluminescence (CL) spectra are presented in this paper. In 2 O 3 films, aimed for gas sensor application, were deposited by spray pyrolysis from 0.2 M InCl 3 –water solutions. The influence of grain size (10–60 nm), film thickness (20–400 nm), pyrolysis temperature ( T pyr  = 400–520 °C), and annealing in the air or nitrogen atmospheres ( T an  = 600–1100 °C) on CL emission of In 2 O 3 is discussed. CL spectra of as-deposited In 2 O 3 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 In 2 O 3 films ( T an > 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 In 2 O 3 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 In 2 O 3 films and the appearance of edge luminescence.