Effect of growth base pressure on the thermoelectric properties of indium antimonide nanowires

We report a study of the effect of the growth base pressure on the thermoelectric (TE) properties of indium antimonide (InSb) nanowires (NWs) synthesized using a vapour-liquid-solid method at different base pressures varying from ambient to high vacuum. A suspended device was used to characterize the TE properties of the NWs, which are zinc-blende structure with < 1 1 0 > growth direction based on transmission electron microscopy (TEM) characterization of the same NWs assembled on the suspended device. The obtained Seebeck coefficient is negative, with the magnitude being smaller than the literature bulk values and increasing with decreasing growth base pressure. These results are attributed to the loss of In from the source materials due to oxidation by residual oxygen in the growth environment and the consequent formation of Sb-doped NWs. The electron mobility and lattice thermal conductivity in the NWs are lower than the corresponding bulk values because of both surface scattering and stronger dopant scattering in the Sb-doped NWs. Based on these findings, it is suggested that growth from In-rich source materials can be used to achieve composition stoichiometry in the NWs so as to increase the Seebeck coefficient and TE figure of merit.