Radiation-induced densification of sol–gel SnO 2:Sb films

Abstract

Thin films of tin oxide doped with antimony (25 at.% nominal) were deposited on either silicon wafers or pyrex plates using the sol–gel dip coating technique. The samples processed on Si consist of a single layer of SnO 2:Sb dried at low temperature (150 °C) for 40 min. Three successive layers, subsequently dried and annealed at 500 °C for 1 h, were coated on pyrex substrates. Single and multilayered samples were then implanted at room temperature with Xe + ions in the 10 14–10 16 cm −2 fluence range. The incident energy (300 keV) was chosen so that the main part of collisional processes occured within the film. The atomic composition and density of the irradiated targets were determined using Rutherford backscattering spectrometry in conjunction with profilometry measurements. Structural informations were obtained from transmission electron microscopy performed on cross-sectional specimen. The results show that ion beam processing is a promising route to densify sol–gel SnO 2:Sb films without overheating the underlying substrate. As an example, the density of a single layer sample irradiated at the highest fluences exceeds 80% of bulk SnO 2 density, whereas only 45% of bulk density could be achieved by means of conventional annealing at 500 °C. A radiation-induced densification is also evidenced in the annealed multideposits. In this case, the whole film is polycrystalline before implantation and becomes amorphous in its densified part.