Regensburg 2016 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 15: Quantum Dots and Wires: Fabrication and Devices
HL 15.2: Vortrag
Montag, 7. März 2016, 15:00–15:15, H16
Hybrid architecture for shallow accumulation mode AlGaAs/GaAs heterostructures with epitaxial gates — S. J. MacLeod1, A. M. See1, A. R. Hamilton1, I. Farrer2, D. A. Ritchie2, •J. Ritzmann3, A. Ludwig3, and A. D. Wieck3 — 1School of Physics, University of New South Wales, Sydney, Australia — 2Cavendish Laboratory, University of Cambridge, United Kingdom — 3Angewandte Festkörperphysik, Ruhr-Universität Bochum, Germany
In accumulation-mode GaAs based heterostructures, the charge carriers are induced by a gate. Usually the top-gate spans the entire transport region and slightly overlaps the ohmic contacts in order to effectively contact and induce a continuous two dimensional conducting region. The close proximity of the contacts to the top-gate can easily cause electrical shorts. The shorting of the top-gate to the contacts is particularly problematic in shallow SISFETs in which the top-gate is an in situ, degenerately doped GaAs cap. Here, we demonstrate a hybrid device where the transport region is a SISFET. The gate recess is realized by a two dimensional electron system induced with a metal gate, insulated from an ohmic contact and the SISFET gate by a dielectric layer. Samples with spacer thicknesses of 50 nm and 160 nm are grown and processed in hybrid devices. Ohmic contact resistance, density tunability, mobiltiy and quantum Hall effect measurements are performed. We observe no shift in the bias point for different cooldown cycles. Additionally devices from different MBE setups, show identical bias point operations and nearly identical mobility.