Thermal Conductivity of GaAs Nanowire Arrays Measured by the 3ω Method

Vertical nanowire (NW) arrays are the basis for a variety of nanoscale devices. Understanding heat transport in these devices is an important concern, especially for prospective thermoelectric applications. To facilitate thermal conductivity measurements on as-grown NW arrays, a common NW-composite device architecture was adapted for use with the 3 omega method. We describe the application of this technique to obtain thermal conductivity measurements on two GaAs NW arrays featuring similar to 130 nm diameter NWs with a twinning superlattice (TSL) and a polytypic (zincblende/wurtzite) crystal structure, respectively. Our results indicate NW thermal conductivities of 5.2 +/- 1.0 W/m-K and 8.4 +/- 1.6 W/m-K in the two samples, respectively, showing a significant reduction in the former, which is the first such measurements on TSL NWs. Nearly an order of magnitude difference from the bulk thermal conductivity (similar to 50 W/m-K) is observed for the TSL NW sample, one of the lowest values measured to date for GaAs NWs.

Automated summary

This study utilized the three omega method to measure the thermal conductivity of two GaAs nanowire arrays with different crystal structures. The results showed that the nanowires with a twinning superlattice structure had a thermal conductivity nearly an order of magnitude lower than that of the bulk material.