Trapping during hopping conduction of electronic defects: A conductivity model for doped transition metal oxides

Abstract

Trapping of electronic defects by dopants, B, and the implications for the electronic conductivity of doped, p-type transition metal oxides, AO, with prevailing hopping conduction of electron holes are analyzed. It is shown that free electron holes as well as electron holes which are trapped by the dopant ions, B, contribute to the electronic conductivity. We derive analytical expressions for the partial conductivities of free and trapped electron holes by translating results from the five-frequency model of impurity diffusion to the conductivity problem. The partial conductivity of trapped electron holes is proportional to the fraction of pairs between electron holes and dopants and the inverse lifetime of the pairs. Our results are applied to acceptor doped oxides and to homovalently doped oxides as well.