Morphology, Structure, and Optical Properties of SnO ( x ) Films

The paper presents the morphological, structural, and optical properties of nanostructured SnO (x) films obtained by molecular beam epitaxy using deposition of tin in an oxygen flux on an oxidized silicon substrate as a function of the annealing temperature of the synthesized structure. The effect of annealing temperature on the structural and phase state of the films is established. The orthorhombic phase of SnO 2 was observed after annealing in air at 500°C. An increase in the annealing temperature up to 800°C leads to the appearance of small fraction of the tetragonal phase of SnO 2 . The effect of the crystal structure on the optical properties of tin oxide films is shown. Ellipsometry revealed a sharp change in the optical constants of the film near the annealing temperature of 500°C. The observed wide absorption band in the range 1.9–3.4 eV is apparently associated with small (approximately 1%) amount of unoxidized metal Sn clusters. Photoluminescence in a wide range of 450–850 nm with a maximum at ~600 nm is observed. An increase in the annealing temperature from 500 to 800°С leads to an increase in the PL intensity by almost a factor of 6.