Control of resistance to enhance the sensitivity of nanocrystalline tin oxide gas sensitive thick film

The sensitivity of a nanocrystalline tin oxide gas sensitive thick film was successfully enhanced by controlling its resistance. For the precise control of the resistance, low temperature catalyst doping (LTCD) method was applied below 300/spl deg/C to dope a Pt catalyst onto nanocrystalline tin oxide particles. Also, a gas sensitive thick film was fabricated using the nanocrystalline tin oxide particles having a size smaller than 10 nm, and it led to an enhanced sensitivity with respect to methane gas. That is, a good and stable sensitivity (R/sub 3500//R/sub 1000/) of 0.64 was achieved after aging for 5 hours at 400/spl deg/C by doping with 5wt% of Pt catalyst onto the tin oxide particle.