Berlin 2015 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 13: Focus Session: Functional Semiconductor Nanowires I (organized by HL)
TT 13.12: Vortrag
Montag, 16. März 2015, 13:00–13:15, EW 201
Seebeck effect measurements on single InAs and GaAs nanowires — •Alexander Hirler1, Vanessa Schaller1, Jonathan Becker1, Bernhard Loitsch1, Stefanie Morkötter1, Julian Treu1, Gerhard Abstreiter1,2, Jonathan Finley1, and Gregor Koblmüller1 — 1Walter Schottky Institut and Physik Department, TU München, Garching, Germany — 2TUM Institute of Advanced Study, Garching, Germany
We present recent results on measurements of the Seebeck coefficient of intrinsic n-type InAs and carbon doped p-type GaAs nanowires (NWs) grown on Si(111) substrates via catalyst free molecular beam epitaxy. To measure the Seebeck effect on single NWs, a temperature gradient is applied via lithographically fabricated heating coils and measured by two resistance thermometers each in a four-point measurement geometry, which also act as electric contacts to the NW. Equipped with another heating resistor the temperature dependent Seebeck-coefficient can be measured as well. Compared to field effect transistor (FET) measurements, the carrier density can be conducted independent of the gate geometry. In addition, the carrier type can be determined from the sign of the Seebeck voltage. Seebeck measurements presented here, demonstrate successful p-type doping of GaAs NWs via carbon. P-type doping and the quantitative measurement of the doping concentration via Seebeck measurements are important steps towards future heterojunction NW devices.