Thermal (Kapitza) resistance of interfaces in compositional dependent ZnO-In2O3 superlattices

Abstract

Compositionally dependent superlattices, In2O3(ZnO)k, form in the ZnO-rich portion of the ZnO-In2O3 phase diagram, decreasing thermal conductivity and altering both the electron conductivity and Seebeck coefficient over a wide range of composition and temperature. With increasing indium concentration, isolated point defects first form in ZnO and then superlattice structures with decreasing interface spacing evolve. By fitting the temperature and indium concentration dependence of the thermal conductivity to the Klemens-Callaway model, incorporating interface scattering and accounting for conductivity anisotropy, the Kapitza resistance due to the superlattice interfaces is found to be 5.0 ± 0.6 × 10−10 m2K/W. This finding suggests that selecting oxides with a compositionally dependent superlattice structure can be a viable approach, unaffected by grain growth, to maintaining low thermal conductivity at high temperatures.

In2O3-Based Thermoelectric Materials: The State of the Art and the Role of Surface State in the Improvement of the Efficiency of Thermoelectric Conversion

“…Despite an increase in conductivity by almost two orders of magnitude to 1 S/cm and a decrease in thermal conductivity to 3.5 W/m·K, the figure of merit for the ZnO:Ga ceramics did not exceed 0.1 at 1000 K. In the case of ZnO:Ga (1%) films deposited by atomic layer deposition (ALD) [112], the conductivity can reach~2 × 10 3 S/cm. However, due to the low Seebeck coefficient, the maximum value of PF is only 0.85 mW/m·K 2 at 330 K. Approximately the same thermoelectric parameters were obtained for sintered ZnO ceramics doped with indium [113][114][115][116][117][118][119]. When the concentration of In 2 O 3 in ZnO was increased to 10 mol%, the thermal conductivity of ZnO:In decreased to~1.6-2.0 W/m·K, and the ZT in samples with optimal doping reached values of~0.1 at 1073 K. According to [109,116], the optimization of the thermoelectric parameters of metal oxides from the ZnO-In 2 O 3 and ZnO-Ga 2 O 3 systems is conditioned by the specificity of point defects [120][121][122], generated at low doping levels, and by the formation of Ga 2 O 3 (ZnO) m and In 2 O 3 (ZnO) m superlattice compounds in the Ga and In highly doped ZnO.…”

“…However, due to the low Seebeck coefficient, the maximum value of PF is only 0.85 mW/m·K 2 at 330 K. Approximately the same thermoelectric parameters were obtained for sintered ZnO ceramics doped with indium [113][114][115][116][117][118][119]. When the concentration of In 2 O 3 in ZnO was increased to 10 mol%, the thermal conductivity of ZnO:In decreased to~1.6-2.0 W/m·K, and the ZT in samples with optimal doping reached values of~0.1 at 1073 K. According to [109,116], the optimization of the thermoelectric parameters of metal oxides from the ZnO-In 2 O 3 and ZnO-Ga 2 O 3 systems is conditioned by the specificity of point defects [120][121][122], generated at low doping levels, and by the formation of Ga 2 O 3 (ZnO) m and In 2 O 3 (ZnO) m superlattice compounds in the Ga and In highly doped ZnO. Such superlattices belongs to the RMO 3 (ZnO) m type of homologous layered oxides [111,119,[121][122][123].…”

“…In these compounds m is an integral number basically denoting the number of Zn-O layers between Ga-O layers. Exactly these multiple complex defects and nanoscale interfaces provide additional strong phonon scattering, leading to a drastic reduction in thermal conductivity in these ZnO-based compounds [109,116,118].…”

Structural features and thermoelectric properties of Al‐doped (ZnO)5In2O3 homologous phases

“…30 On the other hand, basal plane and zig-zag IBs also induce a strong interfacial scattering of phonons, with virtually all possible wavelengths, resulting in a greatly decreased thermal conductivity. 30,31 The best overall ZT values of around 0. . According to other literature reports, Al ions with much smaller ionic radii should predominantly occupy only the trigonal bi-pyramidal sites in the Zn/In zig-zag defect, having less influence on the charge-carrier concentration and the electrical conductivity mechanisms.…”

Synthesis of ZnO nanoparticles with a novel combustion method and their C2H5OH gas sensing properties

“…In this regard, metal oxide semiconductor (MOS) based gas sensors, such as SnO 2 [3], ZnO [4], TiO 2 [5], WO 3 [6] and In 2 O 3 [7] have been extensively studied because of their great potential applications in toxic and flammable gas detection. As a gas sensing material, ZnO possesses some unique advantages: a bandgap of 3.37 eV, large exciton binding energy of 60 meV, resistivity control over the range 10 −3 ∼10 5 Ω·cm, high transparency in the visible range, excellent chemical and thermal stability under the operating condition, thus ZnO has been widely applied in the field of gas/chemical sensors [8][9], optoelectronics [10], laser diodes [11], piezotronics [12], and field emission devices [13].…”