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HL: Fachverband Halbleiterphysik

HL 46: III-V semiconductors: mainly wires and dots

HL 46.3: Vortrag

Dienstag, 12. März 2013, 15:30–15:45, H15

Measurement of Thermoelectric Properties of Indium Arsenide Nanowires — •Philipp Mensch¹, Siegfried Karg¹, Bernd Gotsmann¹, Heinz Schmid¹, Pratyush Das Kanungo¹, Volker Schmidt¹, Hesham Ghoneim¹, Mikael Björk², Valentina Troncale¹, and Heike Riel¹ — ¹IBM Research, Switzerland — ²QuNano AB, Sweden

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 [1]. 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 [2], a thermal conductivity of κ=1.8 W/mK was determined, being a factor of 30 lower than in bulk InAs.

[1] Mingo, Erratum APL 84, 2652 (2004)

[2] S. Karg, et al., J. Electron Mat. (2012) in press