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Publications (10 of 23) Show all publications
Mašláň, S., Šíra, M., Skalická, T. & Bergsten, T. (2019). Four Terminal Pair Digital Sampling Impedance Bridge up to 1 MHz. IEEE Transactions on Instrumentation and Measurement, 68(6), 1860-1869
Open this publication in new window or tab >>Four Terminal Pair Digital Sampling Impedance Bridge up to 1 MHz
2019 (English)In: IEEE Transactions on Instrumentation and Measurement, ISSN 0018-9456, E-ISSN 1557-9662, Vol. 68, no 6, p. 1860-1869Article in journal (Refereed) Published
Abstract [en]

This paper describes a new four terminal pair digital sampling impedance bridge designed for frequency range up to 1MHz and small impedances, such as shunts. The bridge is capable of comparing impedance standards of arbitrary ratios in a full complex plane from approximately 100 kΩ down to 50mΩ, limited by maximum achievable current 3 A. To keep low uncertainties a new multiplexer was designed and a very simple and fully automated linearity correction method based on the pair of calculable resistors was developed and validated. The paper describes the design and details of the bridge topology, basic uncertainty budget and first results of the validation. The expanded uncertainty of impedance module is about 50 μΩ/Ω at 1MHz for impedance ratios up to 1:16 and voltage drops above 10mV and the expanded uncertainty of a phase angle was about 360 μrad/MHz. Expanded uncertainty for frequency 100 kHz about 10 μΩ/Ω was reached. Typical expanded uncertainty for low impedance ratios below 1:1.1 is only 35 μΩ/Ω. Set of measurement of impedance standards of known values and a small international comparison of ac-dc and phase angle errors of current shunts were carried out to validate the bridge capabilities in wide range of impedances. The validation measurements showed the deviations of the bridge are below 35 μΩ/Ω and below 350 μrad at 1 MHz.

Keywords
Bridge circuits, Impedance, Topology, Uncertainty, Standards, Calibration, Multiplexing, impedance measurement, phase comparators, sampling methods, shunts (electrical)
National Category
Natural Sciences
Identifiers
urn:nbn:se:ri:diva-38293 (URN)10.1109/TIM.2019.2908649 (DOI)
Available from: 2019-04-02 Created: 2019-04-02 Last updated: 2019-06-28Bibliographically approved
He, H., Lara-Avila, S., Kim, K., Fletcher, N., Rozhko, S., Bergsten, T., . . . Kubatkin, S. (2019). Polymer-encapsulated molecular doped epigraphene for quantum resistance metrology. Metrologia, 56(4), Article ID 045004.
Open this publication in new window or tab >>Polymer-encapsulated molecular doped epigraphene for quantum resistance metrology
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2019 (English)In: Metrologia, ISSN 0026-1394, E-ISSN 1681-7575, Vol. 56, no 4, article id 045004Article in journal (Refereed) Published
Abstract [en]

One of the aspirations of quantum metrology is to deliver primary standards directly to end-users thereby significantly shortening the traceability chains and enabling more accurate products. Epitaxial graphene grown on silicon carbide (epigraphene) is known to be a viable candidate for a primary realisation of a quantum Hall resistance standard, surpassing conventional semiconductor two-dimensional electron gases, such as those based on GaAs, in terms of performance at higher temperatures and lower magnetic fields. The bottleneck in the realisation of a turn-key quantum resistance standard requiring minimum user intervention has so far been the need to fine-tune the carrier density in this material to fit the constraints imposed by a simple cryo-magnetic system. Previously demonstrated methods, such as via photo-chemistry or corona discharge, require application prior to every cool-down as well as specialist knowledge and equipment. To this end we perform metrological evaluation of epigraphene with carrier density tuned by a recently reported permanent molecular doping technique. Measurements at two National Metrology Institutes confirm accurate resistance quantisation below 5n-1. Furthermore, samples show no significant drift in carrier concentration and performance on multiple thermal cycles over three years. This development paves the way for dissemination of primary resistance standards based on epigraphene

Place, publisher, year, edition, pages
Institute of Physics Publishing, 2019
Keywords
grapheme, measurement standards, molecular doping, quantum Hall effect, Carrier concentration, Electric corona, Gallium arsenide, Graphene, III-V semiconductors, Semiconducting gallium arsenide, Semiconductor doping, Silicon carbide, Two dimensional electron gas, Epitaxial graphene, National metrology institutes, Quantum Hall resistance, Quantum resistance, Resistance standards
National Category
Natural Sciences
Identifiers
urn:nbn:se:ri:diva-39831 (URN)10.1088/1681-7575/ab2807 (DOI)2-s2.0-85070555097 (Scopus ID)
Available from: 2019-10-01 Created: 2019-10-01 Last updated: 2019-10-01Bibliographically approved
Bergsten, T. & Rydler, K. E. (2019). Realization of Absolute Phase and AC Resistance of Current Shunts by Ratio Measurements. IEEE Transactions on Instrumentation and Measurement, 68(6), 2041-2046
Open this publication in new window or tab >>Realization of Absolute Phase and AC Resistance of Current Shunts by Ratio Measurements
2019 (English)In: IEEE Transactions on Instrumentation and Measurement, ISSN 0018-9456, E-ISSN 1557-9662, Vol. 68, no 6, p. 2041-2046Article in journal (Refereed) Published
Abstract [en]

This paper presents a simplified method for realizing absolute phase and ac resistance for current shunts using only impedance ratio measurements. The method is based on three geometrically identical current shunts with different resistances, but with the same inductance, capacitance, and ac-dc resistance change of resistance at ac compared to dc). We demonstrate how the inductance, capacitance, and ac resistance can be calculated from the complex impedance ratio measurements, therefore realizing absolute current shunt impedance. The method gives competitive uncertainties of around 200 μΩ/Ω for amplitude and 400 μrad for phase at 1 MHz in the 1-Ω range.

Keywords
Impedance, Resistance, Current measurement, Impedance measurement, Electrical resistance measurement, Capacitance, Inductance, current shunt, measurement standards, phase measurement, resistance.
National Category
Natural Sciences
Identifiers
urn:nbn:se:ri:diva-38595 (URN)10.1109/TIM.2018.2882927 (DOI)
Available from: 2019-05-09 Created: 2019-05-09 Last updated: 2019-07-01Bibliographically approved
Rydler, K.-E., Bergsten, T. & Eklund, G. (2018). A Method for Realisation of Inductance and Quality Factor to 1 MHz. In: CPEM 2018 - Conference on Precision Electromagnetic Measurements: . Paper presented at 2018 Conference on Precision Electromagnetic Measurements, CPEM 2018, 8 July 2018 through 13 July 2018.
Open this publication in new window or tab >>A Method for Realisation of Inductance and Quality Factor to 1 MHz
2018 (English)In: CPEM 2018 - Conference on Precision Electromagnetic Measurements, 2018Conference paper, Published paper (Refereed)
Abstract [en]

This paper describes a method for realisation of inductance and quality factor to high frequencies by determining the frequency response of gain-and phase-error of an inductance meter using two coils made of a single copper wire. As a starting point a traceable calibration of inductance at 1 kHz is used

Keywords
Impedance measurement, inductance, measurement, measurement standards, measurement techniques, Q measurement, resistance, Electric resistance, Frequency response, Gain and phase error, High frequency HF, Q measurements, Quality factors, Traceable calibration
National Category
Natural Sciences
Identifiers
urn:nbn:se:ri:diva-36599 (URN)10.1109/CPEM.2018.8500813 (DOI)2-s2.0-85056995744 (Scopus ID)9781538609736 (ISBN)
Conference
2018 Conference on Precision Electromagnetic Measurements, CPEM 2018, 8 July 2018 through 13 July 2018
Available from: 2018-12-17 Created: 2018-12-17 Last updated: 2018-12-20Bibliographically approved
Andersson, B.-O., Eklund, G. & Bergsten, T. (2018). Calibration of Gain Ratios on nV-Meters with the Reference Step Method. In: CPEM 2018 - Conference on Precision Electromagnetic Measurements: . Paper presented at 2018 Conference on Precision Electromagnetic Measurements, CPEM 2018, 8 July 2018 through 13 July 2018.
Open this publication in new window or tab >>Calibration of Gain Ratios on nV-Meters with the Reference Step Method
2018 (English)In: CPEM 2018 - Conference on Precision Electromagnetic Measurements, 2018Conference paper, Published paper (Refereed)
Abstract [en]

The Reference Step Method for calibrators can be modified for calibration also of the gain ratios on a meter. The method has earlier been evaluated in the range 100 mV-1000 V on DMM HP 3458A1 and shows that an accuracy of typically < ± 0.2 μ V/V could be obtained. We have investigated the performance of the method when calibrating ratios in the range 1 mV-100 mV on two common nV-meters. In our comparisons with the Josephson Voltage Standard the differences are within ± ± 12μ V/V at the ratio 10m V:1mV and within ± ± 1.3μ V/V at 100mV:10mV.

Keywords
dc voltage build-up, DC voltage ratio, dc voltage scale, low voltage measurements, nanovoltmeter, Voltage measurement, Voltage scaling, DC voltage, Gain Ratio, Josephson voltage standards, Step method, Calibration
National Category
Natural Sciences
Identifiers
urn:nbn:se:ri:diva-36598 (URN)10.1109/CPEM.2018.8501161 (DOI)2-s2.0-85057061401 (Scopus ID)9781538609736 (ISBN)
Conference
2018 Conference on Precision Electromagnetic Measurements, CPEM 2018, 8 July 2018 through 13 July 2018
Available from: 2018-12-17 Created: 2018-12-17 Last updated: 2018-12-17Bibliographically approved
Bergsten, T. & Rydler, K.-E. (2018). Realisation of Absolute Phase and Ac Resistance of Current Shunts by Ratio Measurements. In: CPEM 2018 - Conference on Precision Electromagnetic Measurements: . Paper presented at 2018 Conference on Precision Electromagnetic Measurements, CPEM 2018, 8 July 2018 through 13 July 2018.
Open this publication in new window or tab >>Realisation of Absolute Phase and Ac Resistance of Current Shunts by Ratio Measurements
2018 (English)In: CPEM 2018 - Conference on Precision Electromagnetic Measurements, 2018Conference paper, Published paper (Refereed)
Abstract [en]

This article presents a method for realising absolute phase and ac resistance for current shunts using only impedance ratio measurements. The method is based on three geometrically identical current shunts with different resistances, but with the same inductance, capacitance and ac resistance (change of resistance at ac compared to dc), We demonstrate how the inductance, capacitance and ac resistance can be calculated from the complex impedance ratio measurements, thereby realising absolute current shunt impedance. This method simplifies the procedure of current shunt calibration, since the same impedance ratio setup which is used to compare a shunt to a reference shunt, is used to realise the impedance of the starting reference shunt.

Keywords
Capacitance, current shunt, impedance measurement, inductance, measurement standards, phase measurement, resistance, Electric resistance, Electric resistance measurement, Absolute phase, AC resistance, Complex impedance, Current shunts, Impedance ratios
National Category
Natural Sciences
Identifiers
urn:nbn:se:ri:diva-36601 (URN)10.1109/CPEM.2018.8500935 (DOI)2-s2.0-85057022638 (Scopus ID)9781538609736 (ISBN)
Conference
2018 Conference on Precision Electromagnetic Measurements, CPEM 2018, 8 July 2018 through 13 July 2018
Available from: 2018-12-17 Created: 2018-12-17 Last updated: 2018-12-17Bibliographically approved
He, H., Lara-Avila, S., Bergsten, T., Eklund, G., Kim, K., Yakimova, R., . . . Kubatkin, S. (2018). Stable and Tunable Charge Carrier Control of Graphene for Quantum Resistance Metrology. In: 2018 Conference on Precision Electromagnetic Measurements (CPEM 2018): . Paper presented at 2018 Conference on Precision Electromagnetic Measurements, CPEM 2018, 8 July 2018 through 13 July 2018.
Open this publication in new window or tab >>Stable and Tunable Charge Carrier Control of Graphene for Quantum Resistance Metrology
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2018 (English)In: 2018 Conference on Precision Electromagnetic Measurements (CPEM 2018), 2018Conference paper, Published paper (Refereed)
Abstract [en]

Here we demonstrate a stable and tunable method to alter the carrier concentration of epitaxial graphene grown on silicon carbide. This technique relies on chemical doping by an acceptor molecule. Through careful tuning one can produce chemically doped graphene quantum resistance devices which show long-term stability in ambient conditions and have performance comparable to that of GaAs quantum resistance standards. This development paves the way for controlled device fabrication of graphene quantum hall resistance standards, which can be reliably tailored to operate below 5 T and above 4 K out-of-the-box, without further adjustments from the end-user.

Keywords
chemical doping, graphene, measurement standards, quantum hall effect, Carrier concentration, Gallium arsenide, Graphene devices, III-V semiconductors, Silicon carbide, Acceptor molecules, Ambient conditions, Device fabrications, Long term stability, Quantum Hall resistance, Quantum resistance
National Category
Natural Sciences
Identifiers
urn:nbn:se:ri:diva-36603 (URN)10.1109/CPEM.2018.8501252 (DOI)2-s2.0-85057054632 (Scopus ID)9781538609736 (ISBN)
Conference
2018 Conference on Precision Electromagnetic Measurements, CPEM 2018, 8 July 2018 through 13 July 2018
Note

Funding details: National Research Foundation of Korea, NRF; Funding details: VINNOVA; Funding details: Vetenskapsrådet, VR; Funding details: Stiftelsen för Strategisk Forskning, SSF; Funding details: Nanoscience and Nanotechnology Area of Advance, Chalmers Tekniska Högskola; Funding details: Sjögren’s Syndrome Foundation, SSF, IS14-0053; Funding details: Knut och Alice Wallenbergs Stiftelse

Available from: 2018-12-17 Created: 2018-12-17 Last updated: 2018-12-17Bibliographically approved
Schurr, J., Kalmbach, C.-C. -., Ahlers, F. J., Hohls, F., Kruskopf, M., Müller, A., . . . Haug, R. J. (2017). Magnetocapacitance and dissipation factor of epitaxial graphene-based quantum Hall effect devices. Physical Review B, 96(15), Article ID 155443.
Open this publication in new window or tab >>Magnetocapacitance and dissipation factor of epitaxial graphene-based quantum Hall effect devices
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2017 (English)In: Physical Review B, ISSN 2469-9950, E-ISSN 2469-9969, Vol. 96, no 15, article id 155443Article in journal (Refereed) Published
Abstract [en]

We investigate the properties of the magnetocapacitance and dissipation factor of epitaxial graphene Hall bars with different electrode configurations to gain insight into the underlying physical mechanisms. The dependence of magnetocapacitance and dissipation factor on the magnetic field shows how the screening ability of the two-dimensional electron gas (2DEG) changes at the transition from the nonquantized to the quantized state. Both magnetocapacitance and dissipation factor exhibit a characteristic and correlated voltage dependence, which is attributed to the alternating contraction and expansion of the nonscreening 2DEG regions due to the alternating local electric field. Two regimes with seemingly different voltage dependencies are explained as the limiting cases of weak and strong electric fields of the same general voltage dependence. Electric fields in the plane of the 2DEG are found to cause about three orders of magnitude more ac dissipation than perpendicular electric fields. This strong directionality is attributed to the fact that the electrons are mobile in the plane of the 2DEG but are confined in the third dimension. In the quantized state, not only the screening edge of the 2DEG but also compressible puddles embedded in the bulk cause ac dissipation, as follows from the measured frequency dependence. Finally, characteristic parameters like the width of the screening edge, the threshold voltage, and the charging time of the compressible puddles are determined. .

National Category
Natural Sciences
Identifiers
urn:nbn:se:ri:diva-33172 (URN)10.1103/PhysRevB.96.155443 (DOI)2-s2.0-85037701831 (Scopus ID)
Available from: 2018-01-22 Created: 2018-01-22 Last updated: 2018-08-13Bibliographically approved
Eklund, G., Bergsten, T., Hagen, T., Palafox, L. & Behr, R. (2016). A comparison of the Josephson impedance bridges of PTB and SP. In: CPEM 2016 - Conference on Precision Electromagnetic Measurements, Conference Digest: . Paper presented at 2016 Conference on Precision Electromagnetic Measurements (CPEM 2016), July 10-15, 2016, Ottawa, Canada. , Article ID 7540584.
Open this publication in new window or tab >>A comparison of the Josephson impedance bridges of PTB and SP
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2016 (English)In: CPEM 2016 - Conference on Precision Electromagnetic Measurements, Conference Digest, 2016, article id 7540584Conference paper, Published paper (Refereed)
Abstract [en]

Josephson impedance comparison bridges have been developed at PTB and SP. The bridges are based on programmable Josephson voltage standards. We report the first ever comparison of Josephson impedance bridges performed with 1:1 and 1:10 capacitance ratio measurements up to 2 kHz.

Keywords
Impedance bridge, Josephson array, Josephson impedance bridge, Josephson voltage standard, Capacitance, Josephson junction devices, Voltage measurement, Capacitance ratio, Impedance bridges, Josephson, Josephson voltage standards, Programmable Josephson voltage standard, Electric measuring bridges
National Category
Natural Sciences
Identifiers
urn:nbn:se:ri:diva-27627 (URN)10.1109/CPEM.2016.7540584 (DOI)2-s2.0-84986265790 (Scopus ID)9781467391344 (ISBN)
Conference
2016 Conference on Precision Electromagnetic Measurements (CPEM 2016), July 10-15, 2016, Ottawa, Canada
Note

References: Awan, S., Kibble, B.P., Schurr, J., (2011) Coaxial Techniques for Interference-free Measurements, , London: IET publishing; Behr, R., Kieler, O., Kohlmann, J., Möller, F., Palafox, L., Devolopment and metrological applications of Josephson arrays at PTB (2012) Meas. Sci .Technol, 23 (12), p. 124002; Lee, J., Schurr, J., Nissilä, J., Palafox, L., Behr, R., The Josephson two-Terminal-pair impedance bridge (2010) Metrologia, 47, pp. 453-459; Palafox, L., Behr, R., Nissilä, J., Schurr, J., Kibble, B.P., Josephson impedance bridges as universal impedance comparator CPEM 2012 Conference Digest, , Washington, USA, July 2012; Eklund, G., Bergsten, T., Tarasso, V., Rydler, K.-E., Progress towards an impedance bridge using two programmable josephson Voltage Standards CPEM 2014 Conference Digest, Rio de Janeiro, , Brazil, August 2014; Palafox, L., Behr, R., Schurr, J., Kibble, B.P., Precision 10:1 Capacitance Ratio Measurement using a Josephson Impedance Bridge CPEM 2014 Conference Digest, Rio de Janeiro, Brazil, , August 2014; Eklund, G., Bergsten, T., Rydler, K.-E., A low frequency josephson impedance bridge CPEM 2016 Conference Digest; Hellisttö, P., Nissilä, J., Ojasalo, K., Penttilä, J.S., Seppä, H., AC voltage standard based on a programmable SIS array (2003) IEEE Trans. Instrum. Meas, 52, pp. 533-537. , Apr

Available from: 2016-12-22 Created: 2016-12-21 Last updated: 2019-06-12Bibliographically approved
Eklund, G., Bergsten, T. & Rydler, K.-E. -. (2016). A low frequency Josephson impedance bridge. In: CPEM 2016 - Conference on Precision Electromagnetic Measurements, Conference Digest: . Paper presented at 2016 Conference on Precision Electromagnetic Measurements, CPEM 2016, 10 July 2016 through 15 July 2016.
Open this publication in new window or tab >>A low frequency Josephson impedance bridge
2016 (English)In: CPEM 2016 - Conference on Precision Electromagnetic Measurements, Conference Digest, 2016Conference paper, Published paper (Refereed)
Abstract [en]

We describe a low frequency Josephson impedance bridge and the measurement methods. The bridge is useable below 400 Hz and is based on two programmable Josephson voltage standards. Measurements of 1:1, 1:2 and 1:10 capacitance ratio have been performed and compared with ratio measurements of an inductive voltage divider bridge. © 2016 IEEE.

Keywords
Impedance bridge, Josephson array, Josephson impedance bridge, Josephson voltage standard, Capacitance, Josephson junction devices, Voltage dividers, Voltage measurement, Capacitance ratio, Impedance bridges, Inductive voltage divider, Josephson voltage standards, Measurement methods, Measurements of, Programmable Josephson voltage standard, Electric measuring bridges
National Category
Natural Sciences
Identifiers
urn:nbn:se:ri:diva-27625 (URN)10.1109/CPEM.2016.7540509 (DOI)2-s2.0-84986272615 (Scopus ID)9781467391344 (ISBN)
Conference
2016 Conference on Precision Electromagnetic Measurements, CPEM 2016, 10 July 2016 through 15 July 2016
Note

References: Behr, R., Kieler, O., Kohlmann, J., Möller, F., Palafox, L., Devolopment and metrological applications of Josephson arrays at PTB (2012) Meas.Sci.Technol, 23 (12), p. 124002; Eklund, G., Bergsten, T., Tarasso, V., Rydler, K.-E., Determination of transition error corrections for low frequency stepwise-Approximated josephson sine waves (2011) IEEE Trans. Instrum. Meas, 60 (7), pp. 2399-2403; Lee, J., Schurr, J., Nissilä, J., Palafox, L., Behr, R., The Josephson two-Terminal-pair impedance bridge (2010) Metrologia, 47, pp. 453-459; Eklund, G., Bergsten, T., Tarasso, V., Rydler, K.-E., Progress towards an Impedance Bridge using two Programmable Josephson Voltage Standards (2014) CPEM 2014 Conference Digest, Rio de Janeiro, Brazil, , August; Palafox, L., Behr, R., Schurr, J., Kibble, B.P., Precision 10:1 capacitance ratio measurement using a josephson impedance bridge (2014) CPEM 2014 Conference Digest, Rio de Janeiro, Brazil, , August; Eklund, G., Bergsten, T., Hagen, T., Palafox, L., Behr, R., A comparison of the josephson impedance bridges of PTB and SP CPEM 2016 Conference Digest

Available from: 2016-12-22 Created: 2016-12-21 Last updated: 2018-08-13Bibliographically approved
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0003-2330-9898

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