Analysis of tin oxide thin films fabricated via sol-gel and delayed ignition of combustion processes

Abstract

Metal oxide semiconductor (MOS) gas sensors based on thin film technology offer the potential of higher sensitivity and faster response and recovery than their thick film counterparts. Solution-based approaches are facile and inexpensive routes to prepare thin films. They also provide the means to control and tune the final MOS morphology. Here we present an analysis of tin oxide-based MOS films tens of nanometers thick prepared using two methodologies: a sol-gel process which makes use of tin (II) precursors and, alternatively, via Delayed Ignition of Combustion (DICO). The latter process offers a route to the thin film oxides at lower cure temperatures using ionic oxidizers and organic ignition fuels. We analyze and compare the morphological and compositional properties of the films by means of SEM, TEM, RBS and XRR. For films of comparable thickness, we evaluate the response to acetone down to the sub-ppm level and establish structure-property relationships.