PROCEEDINGS ARTICLE | November 13, 2002
Proc. SPIE. 4936, Nano- and Microtechnology: Materials, Processes, Packaging, and Systems
KEYWORDS: Semiconductors, Oxides, Nanostructuring, Sputter deposition, Annealing, Tungsten, Gases, Bioalcohols, Molybdenum, Carbon monoxide
Nanocomposite materials have attracted considerable research effort in recent years both because of their potential technological applications and because of their relevance to the study of basic physical properties in this range of sizes. On decreasing the dimensions of a material to the nanometre scale, many new effects appear, such as quantum size effects, which can result in new physical properties so that nanostructured materials can show novel optical, electrical, magnetic and catalytic properties that are different from those of bulk materials. The electrical conductivity is also related to the grain size and separation and the gas sensing properties. Many techniques can be employed to fabricate nanocomposite films, such as sol-gel, sputtering and ion implantation. In this work we have deposited mixed oxide of Mo-W, Ti-W and Mo-Ti by sputtering. The production of chemoresistive semiconducting films through selective sublimation processing Ti-W-O, Mo-W-O has been obtained and furthermore the manipulation of a metal-oxide properties by doping Mo:TiO<sub>2</sub> and Ti:MoO<sub>3</sub>. This technique consists of deposition of a mixed-oxide layer, the annealing of the film leads to depletion of the phase with lowest sublimation temperature. The method allows the achievement of films ideal for gas sensing via chemoresistive effect: grain-coalescence inhibition, i.e., nanostructured materials, porous films and modifiable composition. The gas sensing properties of these materials toward gases like CO, NO<sub>2</sub> and ethanol have been studied.
