Berlin 2015 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 4: Focus Session (with TT): Functional semiconductor nanowires I
HL 4.6: Talk
Monday, March 16, 2015, 11:00–11:15, EW 201
Modulation doped GaAs-AlGaAs core-shell nanowires — •Dominik Irber1, Stefanie Morkötter1, Jonathan Becker1, Nari Jeon2, Daniel Rudolph1, Bernhard Loitsch1, Markus Döblinger3, Max Bichler1, Jonathan J. Finley1, Lincoln J. Lauhon2, Gerhard Abstreiter1,4, and Gregor Koblmüller1 — 1Walter Schottky Institut and Physik Department, Technische Universität München, Garching, Germany — 2Department of Materials Science and Engineering, Northwestern University, Evanston, U.S.A. — 3Department of Chemistry, Ludwig-Maximilians-Universität München, Munich, Germany — 4Institute for Advanced Study, Technische Universität München, Garching, Germany
In this work we will present electrical and structural properties of GaAs-AlGaAs core-shell nanowire (NW) MODFETs. The GaAs core was grown on Si (111) substrates via [111]-oriented self-catalyzed growth using MBE, followed by a Si δ-doped radial <110>-oriented AlGaAs shell. Using HRTEM and atom probe tomography (APT), the structure and elemental composition of the NWs were analyzed. The APT analysis revealed the position of the δ-doped layer and the Si dopant concentration, allowing to calculate the expected 2DEG carrier density. Electrical measurements using a top gate geometry verified the expected 2DEG density and further showed very steep switching behavior (SS=70mV/dec) with on/off-ratios >104 at 300K. The device geometry allowed to measure mobility at different sites of the NW. In combination with the APT data the influence of structural parameters on mobility can be studied.