Sintering SnO2 powder in air or under an oxygen atmosphere at different temperatures, leads to polycrystalline samples with nanostructured surface as revealed by atomic force microscopy (AFM). The thermal treatments are also responsible for the variation of the surface electrical properties, as studied by scanning spreading resistance microscopy (SSRM) and scanning tunnelling microscopy and spectroscopy (STM-STS). The surface presents a p-conductance, contrary to the n-type characteristic of the bulk, and a band gap lower than the bulk band gap (3.6 eV). The electrical behaviour at the grain boundaries and the role of oxygen are discussed. X-ray photoelectron spectroscopy (XPS) results show a higher presence of oxygen at the boundaries, which generates a shift of the Fermi level position (EF–EV) towards lower energies.
Journal for Nanoscience and Nanotechnology (JNN) is an international and multidisciplinary peer-reviewed journal with a wide-ranging coverage, consolidating research activities in all areas of nanoscience and nanotechnology into a single and unique reference source. JNN is the first cross-disciplinary journal to publish original full research articles, rapid communications of important new scientific and technological findings, timely state-of-the-art reviews with author's photo and short biography, and current research news encompassing the fundamental and applied research in all disciplines of science, engineering and medicine.