Compensation Of Zn Substitution And Secondary Phase Controls Effective Mass And Weighted Mobility In In And Ga Co-Doped Zno Material

Conductivity s and thermal conductivity k are directly related to carrier concentration while Seebeck coefficient S is inversely proportional to carrier concentration. Therefore, improving thermoelectric (TE) performance is challenging. Here, the first-time analysis of secondary phase-controlled TE performance in terms of density-of-state effective mass m*d, weighted mobility mw and quality factor B is discussed in ZnO system. The results show that the secondary spinel phase Ga2O3(ZnO)(9) not only impacts on k but also on s and S at high temperature, while the effect of carrier concentration seem to be dominant at low temperature. For the high-spinel-segregation sample, a compensation of dopant atoms from the spinel to substitutional sites in the ZnO matrix at high temperature leads to a low decreased rate of temperature dependent m*d. The compensation process also induces a band sharpening, a small mw reduction, and a large B enhancement. As a result, In and Ga co-doped ZnO bulk with the highest spinel segregation achieves the greatest PF improvement by 112.8%, owing to enhanced Seebeck coefficient by 110% as compared to the good Zn-substitution sample. (C) 2021 The Chinese Ceramic Society. Production and hosting by Elsevier B.V.