Cathodoluminescence studies of un-doped and (Cu, Fe, and Co)-doped tin dioxide films deposited by spray pyrolysis

Un-doped and (Cu, Fe, and Co)-doped SnO2 were studied using films deposited by spray pyrolysis. Room temperature cathodoluminescence (CL) was measured. Differences in CL spectra were observed as a function of deposition parameters (Tsub-350–550 °C), the nature and concentration of dopants (0–16 at.%), and the resulting high annealing temperature (Tan = 700–950 °C). A possible luminescence mechanism has been discussed. It was established that changes taking place in CL spectra were caused by the change of both the grain size and crystallinity (stoichiometry) of the surface layer. It was concluded that radiative recombination occurs through shallow donor levels associated with O-vacancies and trapped centers. It was assumed that in SnO2 there are apparently three types of defects forming deep levels located at 0.8–0.9, 1.3–1.4, and ∼1.6 eV from the top of the valence band.