Effect of Ni doping on thick film SnO₂ gas sensor

Ni- and/or Al-doped and undoped SnO₂ thick film gas sensors were prepared using screen printing technique and tested for their LPG gas sensitivity. Tin oxide powder was prepared using a chemical precipitation technique. The sensitivity, optimum working temperature and response time were investigated in relation to dopants as well as preparation route. The results show that the gas sensitivity is affected not only by the additive but the way it is added into the sensor material. The results indicated a reduction in grain size on Al and Ni doping. The results on resistance, response and recovery time were explained in terms of n-p junction formation between SnO₂ and NiO, which increases the depletion barrier height.