Growth of ultrathin Ti films deposited on SnO2 by magnetron sputtering

Low-e multilayers, such as dielectric/Ag/dielectric/glass, are systems extensively used in the field of architectural glass for thermal insulation. However, the physical and chemical phenomena that occur at interfaces are still not fully understood, in particular the function of the sacrificial layer deposited between the dielectric and the silver layers. Most of the time, the sacrificial layer is made of a very thin film of titanium. In order to understand the growth modes of Ti film on SnO2 substrate, as well as the chemical mechanisms taking place at the interface, we have studied by X-ray photoelectron spectroscopy (XPS) the growth of successive amounts of titanium (additions of 0.5 nm) deposited by DC magnetron sputtering on SnO2, substrate. The Ti deposition rate was varied between 0.05 and 0.02 nm/s by varying the current target between 100 and 40 mA in order to determine its influence on the growth mechanism of Ti films. The Ti deposition on SnO2 layers induces the reduction of Sn and partial oxidation of Ti. The Ti films deposited at high deposition rate reach a surface metallic state more rapidly. The XPS results and the fitting of the Sn attenuation signal by a Ti overlayer show that the Ti deposition rate influences the titanium growth mode. We found that the growth mode changes from a Volmer Weber mode for low deposition rate (0.02 nm/s) to a pseudo Frank van der Merwe mode when the deposition rate is enhanced (0.05 nm/s). (C) 2003 Elsevier Science B.V. All rights reserved.