Observation of Anisotropy in Thermal Conductivity of Individual Single-Crystalline Bismuth Nanowires

The thermal conductivity of individual single-crystalline Bi nanowires grown by the on-film formation of nanowires (ON-OFF) has been Investigated. We observed that the thermal conductivity of single-crystalline Bi nanowires Is highly anisotropic. Thermal conductivity of nanowires (diameter similar to 100 nm) in the off-axis [(1) over bar 02) and [110] directions exhibits a difference of similar to 7.0 W/m.K. The thermal conductivity in both growth directions is diameter-dependent, which indicates that thermal transport through the individual Bi nanowires is limited by boundary scattering of both electrons and phonons. This huge anisotropy in thermal conductivities of Bi nanowires suggests the importance of direction-dependent characterization of charge, thermal transport, and thermoelectric properties of Bi nanowires.