Measurement of thermoelectric properties of indium arsenide nanowires

Low-dimensional semi-conducting nano-structures are promising systems to achieve a high figure of merit (ZT) for thermoelectric devices. We report on the thermoelectric properties of indium arsenide (InAs) nanowires (NWs). High ZT values for thin InAs and other III-V NWs are predicted from simulations. We present temperature-dependent measurements of ZT - determining the electrical conductivity σ, the Seebeck coefficient S and the thermal conductivity κ using thermoelectric test structures for single NWs. NWs were grown by MOCVD and in-situ doped with sulfur. They were transferred to SiO2 or Polyimide coated substrates. A resistive heater and four contacts to the NW, each of them serving as resistive thermometer, were structured by electron beam lithography, deposition of a nickel/platinum bilayer and lift-off technique. S and σ were measured for different doping levels with σ ranging from 30 S/cm to 2000 S/cm. S ranges from 10 μV/K for the highest doped NWs up to 180 μV/K for undoped NWs. Using a self-heating technique, a thermal conductivity of κ = 1.8 W/mK was determined, being a factor of 30 lower than in bulk InAs.