Berlin 2015 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 13: Focus Session: Functional Semiconductor Nanowires I (organized by HL)

TT 13.6: Vortrag

Montag, 16. März 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 Abstreiter^1,4, 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.