Sol-gel prepared In/sub 2/O/sub 3/ thin films for ozone sensing

Novel ozone sensors based on In/sub 2/O/sub 3/ thin films on sapphire substrates with interdigitated comb structures have been prepared from indium isopropoxide solutions by the sol-gel process. Highly sensitive films have been obtained by using aged solutions. The annealing temperature was 500/spl deg/C. Compared with earlier thin film devices, the advantages of these sensors include significantly higher ozone sensitivity (as large as 6 at 45 ppb), lower working temperature (below 200/spl deg/C) and low production cost.