Insights into microstructural evolution from nanocrystalline SnO₂ thin films prepared by pulsed laser deposition

Low-dimensional nanostructures of SnO₂ thin films with the interesting features of the tetragonal rutile structure have been prepared by pulsed laser deposition. The microstructural evolution of nanocrystalline SnO₂ thin films has been investigated using x-ray diffraction, transmission electron microscopy, high-resolution transmission electron microscopy, and Raman spectroscopy. Experimental results indicate that the as-prepared SnO₂ thin films appear to be of polycrystalline state, have a large amount of defects, such as oxygen vacancies, vacancy clusters, and local lattice disorder at the interface and surface, and the appearance of a new Raman peak. It suggests that this new Raman peak is closely related to a surface layer of nonstoichiometic SnO_x with different symmetries than SnO₂, or in other words, the new peak marks an additional characteristic of space symmetry of the grain agglomeration of nanocrystalline SnO₂. The study of the microstructural evolution of nanocrystalline SnO₂ is significant for the understanding of the whole structure feature of nanomaterials and for the fabrication of new nanomaterials with favorable properties.