Regensburg 2022 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 25: Poster 1

HL 25.77: Poster

Wednesday, September 7, 2022, 18:00–20:00, P2

Building charge detection in indium antimonide nanowires for scanning tunneling microscopy using gate-defined quantum dots — •Kanji Furuta¹, Felix Jekat¹, Benjamin Pestka¹, Sasa Gazibegovic², Diana Car², Sebastian Heedt³, Marcus Liebmann¹, Thomas Schäpers³, Erik Bakkers², and Markus Morgenstern¹ — ¹II. Phys. Inst. B, RWTH Aachen Univ., Germany — ²Dept. of Appl. Phys., Eindhoven Univ., The Netherlands — ³PGI-9, FZ Jülich, Germany

InSb nanowires are investigated with respect to suitability as a charge detector to be combined with scanning tunneling microscopy. Mechanically exfoliated hexagonal boron nitride (h-BN) as a dielectric is placed onto bottom finger gates (50 nm wide, 30 nm spacing). The nanowires are then aligned and placed mechanically onto h-BN. We present transport measurements on gate-defined quantum dots at temperatures down to 300 mK. Due to the dielectric, the time stability of our device improved to around 5 µeV/h. The charge stability diagram shows Coulomb diamonds with a charging energy of 2.5 meV and an orbital energy of 0.3 meV. Depending on the gate and magnetic field, additional transport channels are occasionally observed, causing additional lines in the charge stability diagram and a shift of the Coulomb peak pattern around a magnetic field of ≈ 400 mT. This points to the presence of an unintentional second quantum dot in the gate region. Different configurations are discussed in terms of their coupling to the leads and the main dot, and their effects on charge detection.