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Displaying 76 - 100 of 141

Low carrier density epitaxial graphene devices on SiC

June 1, 2014
Author(s)
Yanfei Yang, Lung-I Huang, Yasuhiro Fukuyama, Fan-Hung Liu, Mariano Real, Paola Barbara, Chi-Te Liang, David B. Newell, Randolph Elmquist
Monolayer epitaxial graphene grown on a hexagonal silicon carbide (SiC) substrate is typically found to be heavily n-doped (10e13 cm-2) and in most devices made with the as-grown epitaxial graphene the quantized Hall resistance plateau with Landau level

Localization and electron-electron interactions in few-layer epitaxial graphene

May 28, 2014
Author(s)
Randolph E. Elmquist, Fan-Hung Liu, Lung-I Huang, Yasuhiro Fukuyama, Chi-Te Liang, Yanfei Yang
We study the quantum corrections caused by electron-electron (e-e) interactions and localization to the conductivity in few-layer epitaxial graphene, in which the carriers responsible for transport are massive. Our results demonstrate that the diffusive

Precision high-value resistance scaling with a two-terminal cryogenic current comparator

March 1, 2014
Author(s)
Randolph E. Elmquist, George R. Jones, Felipe L. Hernandez-Marquez, Marcos Bierzychudek
We describe a cryogenic two-terminal high-resistance bridge and its application in precision resistance scaling from the quantized Hall resistance (QHR) at RH = RK/2 = 12 906.4035 _ to decade resistance standards with values between 1 M_ and 1 G_. The

Dirac fermion heating, current scaling, and direct insulator-quantum Hall transition in multi-layer epitaxial graphene

August 1, 2013
Author(s)
Randolph E. Elmquist, Fan-Hung Liu, Chang-Shun Hsu, Chiashain Chuang, Tak-Pong Woo, Lung-I Huang Huang, Chi-Te Laing, Yasuhiro Fukuyama, Yanfei Yang
We have performed magnetotransport measurements on multi-layer epitaxial graphene. By increasing the driving current I through our graphene devices while keeping the bath temperature fixed, we are able to study Dirac fermion heating and current scaling in

Graphene Epitaxial Growth on SiC(0001) for Resistance Standards

June 3, 2013
Author(s)
Mariano A. Real, Eric Lass, Fan-Hung H. Liu, Tian T. Shen, George R. Jones Jr., Johannes A. Soons, David B. Newell, Albert Davydov, Randolph Elmquist
A well-controlled technique for high-temperature epitaxial growth on 6H-SiC(0001) substrates is shown to allow development of monolayer graphene that exhibits promise for precise metrological applications. Face-to-face (FTF) and face-to-graphite (FTG)

Characteristics of Graphene for Quantized Hall Effect Measurements

June 1, 2012
Author(s)
Randolph E. Elmquist, Mariano A. Real, Irene G. Calizo, Brian G. Bush, Tian T. Shen, Nikolai N. Klimov, David B. Newell, Angela R. Hight Walker, Randall M. Feenstra
This paper describes concepts and measurement techniques necessary for characterization of graphene in the development of graphene-based quantized Hall effect (QHE) devices and resistance standards. We briefly contrast the properties of graphene produced

Graphene Epitaxial Growth on SiC(0001) for Resistance Standards

June 1, 2012
Author(s)
Mariano A. Real, Tian T. Shen, George R. Jones Jr., Randolph Elmquist, Johannes A. Soons, Albert Davydov
Epitaxial growth of graphene layers on 6H-SiC(0001) substrates have been studied in order to improve graphene's performance for metrological applications. A face-to-face (FTF) sublimation method at 2000 °C and in Ar background atmosphere is used to inhibit

SIM.EM-S5 Voltage, Current and Resistance Comparison

June 1, 2012
Author(s)
Harold Sanchez, Lucas Di Lillo, Gregory Kyriazis, Rodrigo Ramos, Randolph Elmquist, Nien F. Zhang
This paper reports the results of the second Interamerican Metrology System (SIM) comparison on calibration of digital multimeters, performed for strengthening the interaction among National Metrology Institutes (NMIs) and for establishing the degree of

Graphene: Plane and Simple Electrical Metrology?

December 7, 2011
Author(s)
Randolph E. Elmquist, Felipe Hernandez-Marquez, Mariano Real, Tian T. Shen, David B. Newell, Colin J. Jacob, George R. Jones
The development of large-area graphene has direct application to electrical standards including the quantized Hall resistance because of unique characteristics not found in conventional devices. These include symmetrical conduction by electrons and holes

Quantum Hall effect on centimeter scale chemical vapor deposited graphene films

December 7, 2011
Author(s)
Tian T. Shen, Wei Wu, Qingkai Yu, Curt A. Richter, Randolph E. Elmquist, David B. Newell, Yong P. Chen
We report observations of well developed half integer quantum Hall effect on mono layer graphene films of 7 mm × 7 mm in size. The graphene films are grown by chemical vapor deposition on copper, then transferred to SiO2/Si substrates, with typical carrier

Graphene Production for Electrical Metrology

June 1, 2011
Author(s)
Randolph E. Elmquist, David B. Newell, George R. Jones, Felipe L. Marquez-Hernandez, Mariano A. Real, Tian T. Shen
Many material and electronic contributions must be favorable to produce devices with strong quantum Hall effect (QHE) plateaus that are suitable for precise resistance metrology. Even so, metrologically interesting QHE plateaus have been observed in

SIM Comparison of DC Resistance Standards at 1 {O}, 1 M{O}, and 1 G{O}

January 1, 2009
Author(s)
Dean G. Jarrett, Randolph E. Elmquist, Nien F. Zhang, Alejandra Tonina, M Porfiri, Janice Fernandes, H Schechter, Daniel Izquierdo, C Faverio, Daniel Slomovitz, Dave Inglis, Kai Wendler, Felipe Hernandez-Marquez, B Rodriguez
A set of regional comparisons of dc resistance standards at the nominal values of 1 {Ω}, 1 M {Ω}, and 1 G {Ω} has recently been completed in the Sistema Interamericano de Metrogia (SIM) region. The motivation, design, standards, and results of these

Power Loading Effects in Precision 1 Ohm Resistors

August 1, 2008
Author(s)
George R. Jones, Randolph E. Elmquist
Five manganin alloy Thomas-type 1 Ohm resistors serve as primary working standards at the National Institute of Standards and Technology (NIST) in the precision potentiometer direct current comparator (DCC) system used for special 1 Ohm customer

CHARACTERIZATION OF LOADING EFFECTS IN PRECISION 1 Ohm RESISTORS

June 1, 2008
Author(s)
George R. Jones Jr., Randolph Elmquist
Precision standard resistors manufactured within the last two decades using improved construction techniques and materials, such as the resistance alloy Evanohm, have been shown to have excellent environmental characteristics. Power dissipation (or loading

HIGH RESISTANCE SCALING FROM 10 k(OHM) AND QHR STANDARDS USING A CRYOGENIC CURRENT COMPARATOR

June 1, 2008
Author(s)
Randolph Elmquist, George R. Jones Jr., Brian J. Pritchard, Marcos E. Bierzychudek, Felipe L. Hernandez
We describe a cryogenic current comparator (CCC) bridge for resistance scaling that provides improved measurement uncertainty over a range of resistance values from 100 k(Ω) to 1 G(Ω). This CCC is designed for high resistance scaling based directly on a

SIM COMPARISON OF DC RESISTANCE AT 1 Ohm, 1 MOhm, AND 1 GOhm

June 1, 2008
Author(s)
Dean G. Jarrett, Randolph Elmquist, Nien F. Zhang, Alejandra Tonina, Janice Fernandes, Daniel Izquierdo, Dave Inglis, Felipe Hernandez-Marquez
A regional comparison of DC resistance standards at the nominal values of 1 Ohm, 1 MOhm, and 1 GOhm has recently been completed in the System Interamericano de Metrogia (SIM) region. The motivation, design, standards, and results of this regional

UNCERTAINTY EVALUATION IN A TWO-TERMINAL CRYOGENIC CURRENT COMPARATOR

June 1, 2008
Author(s)
Marcos E. Bierzychudek, Randolph Elmquist
In this paper we present the uncertainty evaluation of a new cryogenic current comparator (CCC) bridge designed to compare two-terminal 1M Ω} and 10M Ω} standard resistors with the quantized Hall resistance (QHR) and then scale from these values to other

The NIST Calibration Check Standards Database

June 1, 2007
Author(s)
Kevin G. Brady, Frederic J. de Vaulx, Randolph Elmquist
For several years now, NIST has been a leader in the development and use of Information Technology to process calibration information. Beginning in 1996, researchers designed and developed a calibration database, the NIST Information System to Support

Temperature and Pressure Coefficients of Thomas 1 Ohm Resistors

August 1, 2006
Author(s)
George R. Jones Jr., Randolph Elmquist
In preparing to move the precision 1 ohm measurement service to the new Advanced Measurement Laboratory (AML) in the spring of 2004, staff at the National Institute of Standards and Technology (NIST) first assembled a second precision 1 ohm measurement
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