Theory of gas sensitivity of nano-structured MOX layers. Selection rules for gas sensitive materials

We elaborated a logically closed theory of the conductivity of nano-structured semiconductor material (NSSM) valid in a large range of grain sizes a. It is shown that high sensitivity to electronegative gases (O2, F2, etc.) is observed, when the grain size lies in a range of aSH < a < aCR, where aCR – is a critical size of a grain, below this size charge carrier self-exhaustion regime takes place; aSH – is a grain size, below which the mechanism of superficial hopping conductivity predominates. This hopping mechanism excludes gas sensitivity of the material. Theorem of gas sensitivity of NSSM and the rules of the selection of nano-structures prospective for the fabrication of sensing MOXlayers are formulated.