First-principles studies of the TE properties of [110]-Ge/Si core/shell nanowires with different surface structures

Abstract

Based on first-principle electronic structure calculations and Boltzmann transport theory, we investigate the composition-dependent thermoelectric properties of germanium/silicon core/shell [110]-oriented nanowires, as well as the surface passivation effects. The results demonstrate that the ZT values depend on the surface structure and the Ge/Si ratio. Significantly, for n-type [110]-Ge/Si core/shell NWs (about 2.6 nm in diameter) ZT = 0.65 at 300 K can be obtained, that is 65 times that of bulk Si, and 1.8 times that of SiNW without the core/shell structure at the same temperature.