Single layer In-O atomic sheets as phonon and electron barriers in ZnO-In2O3 natural superlattices: Implications for thermoelectricity

Abstract

The phases in the ZnO half of the ZnO-In2O3 binary system are natural superlattices consisting of periodic stacking of single InO2 sheets separated by indium doped ZnO blocks with a spacing that depends on the composition according to the relationship In2O3(ZnO)k.Characterization by combined, atomic resolution, aberration-corrected scanning transmission electron microscopy (STEM) and electron energy loss spectroscopy (EELS) analysis, indicates that the atomic structure of each InO2 layer consists of a single continuous sheet of octahedrally-coordinated InO2. The sheets also are crystallographic inversion boundaries. Analysis of the electrical conductivity, thermal conductivity and Seebeck coefficient data at 800 o C indicates that the InO2 sheets not only decrease thermal conductivity by phonon scattering but also create potential barriers to electron transport. The origin of the potential barriers, the role of piezoelectric effects and their dependence on superlattice spacing is discussed qualitatively. It is also argued that the crystallographically-aligned InO2 sheets within individual grains are also transport barriers in randomly oriented polycrystalline materials.

Deposition, Characterization, and Performance of Spinel InGaZnO4

“…15 Enlarged orbital overlaps increase the delocalization of states at the bottom of the conduction band. 12,16,17 Therefore, electron mobility increases with increasing In concentration 18 shows different electrical properties like improved thermoelectric performance, 19,20 confinement of holes, 21 and enhancement of electrons conduction paths, 12,22 resulting in anisotropic mobility as is observed on grown monocrystals. 23 Those effects are all related to the layered arrangement of InO 2 segments, where the orbital overlap is maximal.…”

Design of Heusler alloys using Co-VB-Sn (VB = V, Nb, Ta) atoms within ab initio calculations for thermoelectric applications

“…ii) 2D materials based on NaxCoO2, In4Se3, SnSe, Bi-SnSe and Na-SnSe that can reach ZT ≈ 2 [30]. iii) superlattices that are formed by periodic arrangement of successive adjacent layers, which can scatter phonons and ultimately decreases thermal conductivity, and increases S coefficient by increasing the density of states at the Fermi level [31]. Bi2Te3/Sb2Te3, Bi2Te3/Bi2Se3 as well as PbSeTe/PbTe are among the structures studied [32].…”