A theoretical investigation of the power-law response of metal oxide semiconductor gas sensors II: Size and shape effects

The power-law response of nanosized metal oxide semiconductor gas sensors were theoretically investigated using the previously proposed concept of reduced transducer and receptor functions in our previous paper. The size and shape effects on the power-law response are theoretically revealed through derivations of the power-law exponents for gas sensors consisting of large and nanosized grains, respectively. It is found that the ratio of grain size to depletion width modulates the transducing mechanism and in turn the power-law response of gas sensors. At grain sizes equal to or less than the depletion width, the power-law exponent is inversely proportional with the grain size and linearly proportional with the surface to volume ratio of the grain. The power-law response is also experimentally characterized and found to be well consistent with our theoretical results. (C) 2017 Elsevier B.V. All rights reserved.