Electrical and Thermal Transport Properties in Layer-Structured (ZnO)_<i>m</i>In₂O₃(<i>m</i>=5 and 9) Ceramics

Abstract

The electrical and thermal transport properties are characterized for layer-structured (ZnO)mIn2O3 (m=5 and 9) (ZmIO) ceramics of near theoretical densities. The results of the low temperature Hall effect study suggested that the InO2- layers, which have oxygen defects, determine the carrier scattering mechanism of the material, and explain the previously demonstrated two-dimensional character of the carrier transport behavior. From an adaptation of the Wiedemann–Franz law, the lattice thermal conductivity (κL) of ZmIOs at 300 K is estimated to be ∼2.6 W/mK; this value is nearly one fifteenth of that for Al-doped ZnO ceramics (∼40 W/mK). These results suggest that the two-dimensional structure consisting of the InZnmOm+1+ and InO2- sub-lattices gives rise to the strong electrical anisotropy and the low κL which is attributed to the reduced mean free path of the phonon, similar to artificial super-lattice materials.