Effect of Co doping on chemosorbed oxygen accumulation and gas response of SnO2 under dynamic program cooling

During the process of metal oxide semiconductors (MOS) gas sensing, the chemisorbed oxygen on the surface plays a significant important role, which determines the surface reactivity and controls the film conductivity. Therefore, it is necessary to improve the amount of chemisorbed oxygen on MOS surface. In this paper, the effect of doping on the accumulation of chemosorbed oxygen on SnO2 surface was studied. SnO2, Co-SnO2 and Nb-SnO2 were successfully synthesized via nonaqueous sol-gel method to study the effect of acceptor doping and donor doping on accumulation of chemosorbed oxygen and gas response. And dynamic program cooling (DPC) was also carried out in different concentrations of acetone and different gases respectively to obtain the R-T curve and gas response. The results showed that the Co doped SnO2 obviously improved the accumulation of chemosorbed oxygen and dynamic gas response, while the Nb doping has little improvement. The reason of these results was also analyzed by band theory in this paper.