First-principles analysis on Seebeck coefficient in zinc oxide nanowires for thermoelectric devices

Abstract

The Seebeck coefficient of ZnO0001 nanowires was simulated on the basis of first- principles calculation, to discuss the potential for future application to thermoelectric devices. Simulation procedure by means of the electronic band structure with one-dimensional periodic boundary condition was presented, and dependences of the Seebeck coefficient on temperature and carrier concentration have been investigated for many kinds of n- or p-doped ZnO0001 nanowire models with 1.00-2.65 nm diameter. For the direct band-gap semiconducting models, a magnitude of the Seebeck coefficient increases gradually as temperature rises in the p-doped state, and a significant effect of miniaturization to nanowire on the Seebeck coefficient has been brought out, such as about 1000 μV/K in the p-doped state and -820 μV/K in the n-doped state for the (ZnO)24 nanowire model with 1 × 1017 cm-3 carrier concentration at room temperature. Similar characteristics of the Seebeck coefficient were observed for some indirect band-gap semiconducting models. At the end of this paper, the simulation was extended to the no band-gap conducting models with some modification.