Berlin 2012 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 91: Poster Session: Spintronics / Magnetic Semiconductors / Transport

HL 91.19: Poster

Donnerstag, 29. März 2012, 16:00–19:00, Poster D

Shubnikov-de Haas oscillations and quantum Hall effect in Gd-implanted Al_xGa_1−xN/GaN heterostructures — •Stepan Shvarkov¹, Dirk Reuter¹, Yvon Cordier², and Andreas D. Wieck¹ — ¹Angewandte Festkörperphysik, Ruhr-Universität Bochum, D-44780 Bochum, Germany — ²CRHEA-CNRS, F-06560 Valbonne, France

We present a study of the magnetotransport properties of Al_xGa_1−xN/GaN heterostructurs. The samples were grown by molecular beam epitaxy on Si(111) substrates. The transport properties of the samples doped with Gd and undoped samples are compared. The Gd ions were introduced by focused ion beam implantation with fluences from 8×10¹⁰ cm⁻² to 1×10¹² cm⁻² . As-grown samples reveal quantum interference effects such as weak localization and electron-electron interactions in low magnetic fields. At high magnetic fields B > 6 T, Shubnikov-de Haas (SdH) oscillations and quantum Hall effect (QHE) were observed. In analyzing the measured data, elastic and inelastic scattering times, mobility, carrier concentration and effective mass of the electrons in unimplanted and implanted samples were determined. The implantation strongly affects the quality of the heterostructures, causing strong decrease in carrier mobility at low temperatures. Nevertheless, SdH-oscillations and the QHE are still well pronounced in samples implanted with a fluence of 1×10¹¹ cm⁻².