Print Email Facebook Twitter Integrated impedance bridge for absolute capacitance measurements at cryogenic temperatures and finite magnetic fields Title Integrated impedance bridge for absolute capacitance measurements at cryogenic temperatures and finite magnetic fields Author Verbiest, G.J. (JARA-FIT and 2nd Institute of Physics) Janssen, H. (JARA-FIT and 2nd Institute of Physics) Xu, D. (TU Delft QRD/Kouwenhoven Lab; TU Delft QuTech Advanced Research Centre; Kavli institute of nanoscience Delft) Ge, X. (JARA-FIT and 2nd Institute of Physics) Goldsche, M. (Forschungszentrum Jülich GmbH; JARA-FIT and 2nd Institute of Physics) Sonntag, J. (Forschungszentrum Jülich GmbH; JARA-FIT and 2nd Institute of Physics) Khodkov, T. (Forschungszentrum Jülich GmbH; JARA-FIT and 2nd Institute of Physics) Banszerus, L. (Forschungszentrum Jülich GmbH; JARA-FIT and 2nd Institute of Physics) Von Den Driesch, N. (Forschungszentrum Jülich GmbH) Date 2019 Abstract We developed an impedance bridge that operates at cryogenic temperatures (down to 60 mK) and in perpendicular magnetic fields up to at least 12 T. This is achieved by mounting a GaAs HEMT amplifier perpendicular to a printed circuit board containing the device under test and thereby parallel to the magnetic field. The measured amplitude and phase of the output signal allows for the separation of the total impedance into an absolute capacitance and a resistance. Through a detailed noise characterization, we find that the best resolution is obtained when operating the HEMT amplifier at the highest gain. We obtained a resolution in the absolute capacitance of 6.4 aF/Hz at 77 K on a comb-drive actuator while maintaining a small excitation amplitude of 15 kBT/e. We show the magnetic field functionality of our impedance bridge by measuring the quantum Hall plateaus of a top-gated hBN/graphene/hBN heterostructure at 60 mK with a probe signal of 12.8 kBT/e. To reference this document use: http://resolver.tudelft.nl/uuid:f26a9205-24ae-4d33-a569-565a19eb5109 DOI https://doi.org/10.1063/1.5089207 ISSN 0034-6748 Source Review of Scientific Instruments, 90 (8) Part of collection Institutional Repository Document type journal article Rights © 2019 G.J. Verbiest, H. Janssen, D. Xu, X. Ge, M. Goldsche, J. Sonntag, T. Khodkov, L. Banszerus, N. Von Den Driesch, More Authors Files PDF 1.5089207.pdf 2.88 MB Close viewer /islandora/object/uuid:f26a9205-24ae-4d33-a569-565a19eb5109/datastream/OBJ/view