A5047823808- Quantum and electron transport phenomena
- Advanced Electrical Measurement Techniques
- Graphene research and applications
- Magnetic Field Sensors Techniques
- Sensor Technology and Measurement Systems
- Electrical and Bioimpedance Tomography
- Advancements in PLL and VCO Technologies
- Physics of Superconductivity and Magnetism
- Analog and Mixed-Signal Circuit Design
- Surface and Thin Film Phenomena
- Scientific Measurement and Uncertainty Evaluation
- Atomic and Subatomic Physics Research
- Neural Networks and Applications
- Carbon Nanotubes in Composites
- 2D Materials and Applications
- Electrostatic Discharge in Electronics
- Magneto-Optical Properties and Applications
- Embedded Systems Design Techniques
- Mechanical and Optical Resonators
- Boron and Carbon Nanomaterials Research
- Formal Methods in Verification
- Numerical Methods and Algorithms
- Geophysical and Geoelectrical Methods
- Magnetic Properties and Applications
- Model-Driven Software Engineering Techniques
National Institute of Standards and Technology
2022-2024
Joint Quantum Institute
2022-2023
University of Maryland, College Park
2022-2023
Physical Measurement Laboratory
2022-2023
Istituto Nazionale di Ricerca Metrologica
2014-2022
Polytechnic University of Turin
2014-2022
National Institute of Advanced Industrial Science and Technology
2017
A two-channel AC voltage source based on digital synthesis is reported. We present measurement results of some the key properties at 1 kHz with applications like impedance bridges in mind. Measurements show that amplitude ratio channels has a stability (Allan standard deviation) one part 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">8</sup> for 30 min measurement. The phase difference between also stable within 0.1 μrad.
Abstract Interlaboratory comparisons of the quantized Hall resistance (QHR) are essential to verify international coherence primary impedance standards. Here, we report on investigation stability p-doped graphene-based QHR devices at direct and alternating currents CMI, KRISS, PTB. To improve electronic transport properties polymer-encapsulated devices, they were shipped in an over-pressurized chamber. The agreement with R K /2 current was order 1 nΩ Ω −1 between 3.5 7.5 T a temperature 4.2...
Fully digital impedance bridges are emerging as measuring instruments for primary electrical metrology and the realization of units scales. This article presents a comprehensive analysis electronic fully both generating (based on digital-to-analog converters) digitizing analog-to-digital bridges. The sources measurement error analyzed in detail expressed by explicit mathematical formulas ready to be applied specific bridge case interest. same can employed also basis optimize design operating...
Advances in the development of graphene-based technology have enabled improvements DC resistance metrology. Devices made from epitaxially grown graphene replaced GaAs-based counterparts, leading to an easier and more accessible realization ohm. By optimizing scale growth, it has become possible fabricate quantized Hall array standards (QHARS) with nominal values between 1 kΩ 1.29 MΩ. One these QHARS device designs accommodates a value about 1.01 MΩ, which ideal candidate pursue...
Abstract This paper addresses the calibration of lock-in amplifiers in low frequency range. A simple but effective setup implemented at INRIM is described. includes a stable low-voltage source, composed digital sine wave generator and cascade two voltage dividers, one inductive resistive. The magnitude error error, which can be determined with an uncertainty order 10 −4 or better, that is, orders lower than typical accuracy specification. system operate input from 0.1 µV to few hertz about 1...
Abstract This paper describes the calibration of a 10 nF capacitance standard traced to DC quantum Hall resistance primary using multi-purpose digital impedance bridge. The bridge can directly compare unlike impedances in fully (FD) mode, so be calibrated by direct comparison against AC standard. measurement ability FD mode was evaluated various angles, and voltage dependencies were improved selecting appropriate for high current arms also an additional injection circuit. Thereby, accuracy...
We present a capacitance build-up method suitable for the determination of measurement error meter. The requires only small number uncalibrated base capacitors, to be connected in parallel various combinations, and single calibrated capacitor, which provides traceability. outcome is both meter calibration all capacitors; it can therefore also considered scaling method. method's equations, cast matrix form, express estimates uncertainties quantities interest. As an example application,...
This work reports the dynamics of transient hole doping in epitaxial graphene devices by using nitric acid as an adsorbent. The timescales associated with corresponding desorption processes are extracted from data. understanding reversible without gating is crucial importance to those fabricating a particular functionality. Measurements electrical and optical properties several postexposure were performed transport temperatures between 300 1.5 K. Ambient conditions applied nontransport...
We demonstrate the preparation of both armchair (AC) and zigzag (ZZ) epitaxial graphene nanoribbons (GNRs) on $4H$-SiC using a polymer-assisted, sublimation growth method. Historically, GNRs depended quality or smoothness surface changes during growth. The physical phenomenon terrace step formation introduces risk GNR deformation along sidewalls, but is heavily mitigated by this polymer-assisted Two widths (100 50 nm) are examined electrically optically for AC ZZ GNRs. Our electrical results...
In this paper, we report on the experimental demonstration of single-slit diffraction exhibited by electrons propagating in encapsulated graphene with an effective de Broglie wavelength corresponding to their attributes as massless Dirac fermions. Nanometer-scale device designs were implemented fabricate a followed five detector paths. Predictive calculations also utilized readily understand observations reported. These required modeling wave propagation ideal case scenarios reported more...
A mathematical approach is adopted for optimizing the number of total device elements required obtaining high effective quantized resistances in graphene-based quantum Hall array devices. This work explores an analytical extension to use star–mesh transformations such that fractal-like, or recursive, designs can yield enough (like 1 EΩ, arguably highest resistance with meaningful applicability) while still being feasible build modern fabrication techniques. Epitaxial graphene are tested,...
The core objective of EMPIR project 17RPT04 VersICaL is to improve the European measurement infrastructure for electrical impedance, with particular emphasis on capabilities developing NMIs and calibration centres. will seek exploit results existing research digital impedance bridges (DIBs) by designing, constructing validating simple, affordable versions suitable realise scale in range 1 nF 10 μF mH H relative uncertainties -5 -6 . first project, including bridge designs details a polyphase...
GIQS: Graphene Impedance Quantum Standard is a Joint Research Project of the European Metrology Programme for Innovation and (EMPIR). The project objective to combine novel digital impedance measurement bridges with graphene-based ac quantum Hall resistance standards in simplified cryogenic environment, achieve simple, user-friendly suitable primary realisation units national metrology institutes, calibration centers, industry.
We report on the development of a current amplifier for measuring small currents from mesoscopic electronic devices at low temperatures down to milli-Kelvin range. In our setup, superconducting quantum interference device (SQUID) located mixing chamber stage dilution refrigerator is used as first-stage amplifier, thereby improving noise floor 8 × 10−27 A2/Hz, which one order magnitude those obtained by conventional methods that utilize semiconductor-based cryogenic amplifier. show...
This paper describes the characterization of quantum anomalous Hall (QAH) effect resistor with Chromium-doped Bismuth Antimony Telluride efforts in coupling directly to a programmable Josephson voltage standard (PJVS) at zero magnetic field. The precision measurement QAH resistance was performed under presence microwave signal biased PJVS. Understanding such will help improve experimental set-up for integrating multiple electrical standards single system.
We present here a comprehensive analysis of the error sources in electronic fully-digital impedance bridges, for both sourcing and digitizing bridges. This work can be used as basis to optimize design operating parameters digital evaluation uncertainty.
Describes the realization and preliminary tests of a two terminal-pair digital impedance bridge. The bridge, with very simple architecture, is based on commercial two-channel signal synthesizer, synchronous detector. bridge can perform comparisons between impedances having arbitrary phase magnitude ratio: its balance achieved automatically in less than minute. R-C calibrated standard, at kHz frequency 100 kΩ level, give ratio errors order 10 <sup...
In this work, the limiting factors for developing metrologically useful arrays from epitaxial graphene on SiC are lifted with a combination of centimeter-scale, high-quality material growth and implementation superconducting contacts. Standard devices metrology have been restricted to having single quantized value output based ν = 2 Landau level. With demonstrations herein multiple outputs values available simultaneously, these versatile can be used disseminate ohm globally. Such designed...
This paper describes a calibration method for 10 nF capacitance standard from the primary of dc quantum Hall resistance using multi-purpose digital coaxial bridge. The was calibrated by direct comparison against ac kΩ-its value is traced to resistance-using bridge in fully quadrature mode. preliminary confirmed comparing with reference within uncertainty level <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-6</sup> .
<p class="Abstract"><span lang="EN-US">The quantum Hall effect is the basis for realisation of resistance and impedance units in International System since 2019. This paper describes a cryogenic probe that allows to set graphene devices quantisation conditions helium bath (4.2 K) magnetic fields up 6 T, perform precision measurements AC regime with bridges. The has full coaxial wiring, isolated from structure, holds device TO-8 socket. First, characterization experiments are...
We have demonstrated the fabrication of both armchair and zigzag epitaxial graphene nanoribbon (GNR) devices on 4H–SiC using a polymer-assisted sublimation growth method. The phenomenon terrace step formation has traditionally introduced risk GNR deformation along sidewalls, but method helps mitigate this risk. Each type 50 nm wide is examined electrically optically (armchair zigzag), with latter being check quality former alternating current to investigate resistance attenuation from...