Effect of Foreign Metal Doping on the Gas Sensing Behaviors of SnO2-Based Gas Sensor
Recently, we have proposed some theoretical models, power laws and effect of particle shape and size, for semiconductor gas sensors. The models show that a depletion theory of semiconductor can be combined with the dynamics of adsorption and/or reactions of gases on the surface. In the case of SnO2, the relative resistance (R/R0) is proportional to PO 2 n, where n is a constant value (n=1/2) on oxygen partial pressure. In addition, carrier concentration in SnO2 influences depth of the depletion. In this study, to experimentally reveal such effects, we tried to control the carrier concentration in SnO2 by foreign doping and examined their electrical resistance and sensor response. Correlations between doping concentration, crystalline size, and partial pressures of oxygen and H2 on the electric resistance are discussed to reveal the material design for semiconductor gas sensors.
Alan K.T. Lau, J. Lu, Vijay K. Varadan, F.K. Chang, J.P. Tu and P.M. Lam
K. Suematsu et al., "Effect of Foreign Metal Doping on the Gas Sensing Behaviors of SnO2-Based Gas Sensor ", Advanced Materials Research, Vols. 47-50, pp. 1502-1505, 2008