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Search Publications by: David B. Newell (Fed)

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Displaying 51 - 75 of 150

Utilizing confocal laser scanning microscopy for rapid optical characterization of graphene

November 20, 2018
Author(s)
Vishal Panchal, Yanfei Yang, Guangjun Cheng, Jiuning Hu, Mattias Kruskopf, Chieh-I Liu, Albert Rigosi, Christos Melios, Angela R. Hight Walker, David B. Newell, Olga Kazakova, Randolph Elmquist
Confocal laser scanning microscopy (CLSM) is a non-destructive, highly-efficient optical characterization method for large-area analysis of graphene on different substrates, which can be applied in ambient air, does not require additional sample

Quantum transport in graphene p-n junctions with Moire superlattice modulation

July 12, 2018
Author(s)
Jiuning Hu, Albert Rigosi, Ji Ung Lee, Hsin Y. Lee, Yanfei Yang, Chieh-I Liu, Randolph Elmquist, David B. Newell
This work presents simulations of quantum transport in graphene p-n junctions (pnJs) in which Moire superlattice potentials are incorporated to demonstrate the interplay of the effect of pnJs and Moire superlattice potentials. It is shown that the

Epitaxial Graphene for High-Current QHE Resistance Standards

July 9, 2018
Author(s)
Mattias Kruskopf, Jiuning Hu, Bi Y. Wu, Yanfei Yang, Hsin Y. Lee, Albert F. Rigosi, David B. Newell, Randolph E. Elmquist
We report the growth of large-area monolayer graphene on the centimeter scale using an optimized growth process allowing for reproducibility and morphology improvements. Magneto-transport measurements on graphene quantum Hall effect devices demonstrate the

Epitaxial Graphene p-n Junctions

July 9, 2018
Author(s)
Jiuning Hu, Mattias Kruskopf, Yanfei Yang, Bi Y. Wu, Jifa Tian, Alireza R. Panna, Albert F. Rigosi, Hsin Y. Lee, George R. Jones Jr., Marlin E. Kraft, Dean G. Jarrett, Kenji Watanabe, Takashi Taniguchi, Randolph E. Elmquist, David B. Newell
We report the fabrication and measurement of top gated epitaxial graphene p-n junctions where exfoliated hexgonal boron nitride (hBN) is used as the gate dielectric. The four terminal longitudinal resistance across a single junction is well quantized at R_

A Table-Top Graphene Quantized Hall Standard

July 8, 2018
Author(s)
Albert F. Rigosi, Alireza R. Panna, Shamith U. Payagala, George R. Jones Jr., Marlin E. Kraft, Mattias Kruskopf, Bi Y. Wu, Hsin Y. Lee, Yanfei Yang, Dean G. Jarrett, Randolph E. Elmquist, David B. Newell
We report the performance of a quantum standard based on epitaxial graphene maintained in a 5 T table-top cryocooler system. The ν = 2 resistance plateau, with a value of RK-90/2, is used to scale to 1 kΩ, allowing comparisons of the performance of a

Examining epitaxial graphene surface conductivity and quantum Hall device stability with Parylene passivation

March 20, 2018
Author(s)
Albert F. Rigosi, Chieh-I Liu, Bi Y. Wu, Hsin Y. Lee, Mattias Kruskopf, Yanfei Yang, Heather M. Hill, Jiuning Hu, Emily G. Bittle, Jan Obrzut, Angela R. Hight Walker, Randolph E. Elmquist, David B. Newell
When it comes to the advancement of quantized Hall resistance (QHR) standards, homogeneous, single-crystal, monolayer epitaxial graphene (EG) is the most promising candidate. EG-based quantum Hall devices, though emerging as a useful tool for metrology

Measuring the dielectric and optical response of millimeter-scale amorphous and hexagonal boron nitride films grown on epitaxial graphene

December 1, 2017
Author(s)
Albert F. Rigosi, Heather M. Hill, Nicholas R. Glavin, Sujitra J. Pookpanratana, Yanfei Yang, Alexander G. Boosalis, Jiuning Hu, Anthony Rice, Andrew A. Allerman, Nhan V. Nguyen, Christina A. Hacker, Randolph E. Elmquist, Angela R. Hight Walker, David B. Newell
Monolayer epitaxial graphene (EG), grown on the Si face of SiC, is an advantageous material for a variety of electronic and optical applications. EG forms as a single crystal over millimeter- scale areas and consequently, the large scale single crystal can

Probing the dielectric response of the interfacial buffer layer in epitaxial graphene via optical spectroscopy

November 28, 2017
Author(s)
Heather M. Hill, Albert Rigosi, Sugata Chowdhury, Yanfei Yang, Nhan Van Nguyen, Francesca Tavazza, Randolph Elmquist, David B. Newell, Angela R. Hight Walker
Monolayer epitaxial graphene (EG) is a suitable candidate for a variety of electronic applications. One advantage of EG growth on the Si face of SiC is that it develops as a single crystal, as does the layer below, referred to as the interfacial buffer

Measurement of the Planck constant at the National Institute of Standards and Technology from 2015 to 2017

July 28, 2017
Author(s)
Darine El Haddad, Frank Seifert, Leon Chao, Antonio Possolo, David B. Newell, Jon R. Pratt, Carl J. Williams, Stephan Schlamminger
Researchers at the National Institute of Standards and Technology(NIST) estimate the value of the Planck constant as h = 6.62606994(10) x 10^-34 Js, hence with relative standard uncertainty 15.3 x 10^-9. This measurement result is based on over 17,000

Coulomb drag and counterflow Seebeck coefficient in bilayer-graphene double layers

July 21, 2017
Author(s)
Jiuning Hu, David B. Newell, Jifa Tian, Nikolai N. Klimov, Tailung Wu, Yong Chen
We have fabricated bilayer-graphene double layers separated by a thin (~20 nm) boron nitride layer and performed Coulomb drag and counterflow thermoelectric transport measurements. The measured Coulomb drag resistivity is nearly three orders smaller in

Electrical stabilization of surface resistivity in epitaxial graphene systems by amorphous boron nitride encapsulation

May 25, 2017
Author(s)
Albert F. Rigosi, Chieh-I Liu, Nicholas R. Glavin, Yanfei Yang, Heather M. Hill, Jiuning Hu, Angela R. Hight Walker, Curt A. Richter, Randolph E. Elmquist, David B. Newell
Homogeneous monolayer epitaxial graphene (EG) is an ideal candidate for the development of millimeter-sized devices with single-crystal domains. A clean fabrication process was used to produce EG-based devices with n-type doping level of order 10^12 cm^-2

Preservation of surface conductivity and dielectric loss tangent in large-scale, encapsulated epitaxial graphene measured by non-contact microwave cavity perturbations

May 19, 2017
Author(s)
Albert F. Rigosi, Nicholas R. Glavin, Chieh-I Liu, Yanfei Yang, Jan Obrzut, Heather M. Hill, Jiuning Hu, Hsin Y. Lee, Angela R. Hight Walker, Curt A. Richter, Randolph E. Elmquist, David B. Newell
Regarding the improvement of current quantized Hall resistance (QHR) standards, one promising avenue is the growth of homogeneous monolayer epitaxial graphene (EG). A clean and simple process was used to produce large, precise areas of EG. Properties like

CODATA Recommended Values of the Fundamental Physical Constants: 2014

November 22, 2016
Author(s)
Peter J. Mohr, David B. Newell, Barry N. Taylor
This paper gives the 2014 self-consistent set of values of the constants and conversion factors of physics and chemistry recommended by the Committee on Data for Science and Technology (CODATA). These values are based on a least-squares adjustment that

Bridging classical and quantum mechanics

September 28, 2016
Author(s)
Darine El Haddad, Frank C. Seifert, Leon S. Chao, Shisong Lee, David B. Newell, Jon R. Pratt, Carl J. Williams, Stephan Schlamminger
Using a watt balance and a frequency comb, a mass-energy equivalence is derived. The watt balance compares mechanical power measured in terms of the meter, the second, and the kilogram to electrical power measured in terms of the volt and the ohm. A direct

CODATA Recommended Values of the Fundamental Physical Constants: 2014

September 26, 2016
Author(s)
Peter J. Mohr, David B. Newell, Barry N. Taylor
This paper gives the 2014 self-consistent set of values of the constants and conversion factors of physics and chemistry recommended by the Committee on Data for Science and Technology (CODATA). These values are based on a least-squares adjustment that

Design of a Table-Top Watt Balance

July 26, 2016
Author(s)
Stephan Schlamminger, Jon R. Pratt, David B. Newell, Frank C. Seifert, Michael Liu, Leon S. Chao, Luis Manuel Pea Prez, Shisong Li, Darine El Haddad
Measurements of the Planck constant with watt balances using 1 kg masses have achieved relative standard uncertainties below 2 x 10-8. Having established a metrological link between the kilogram and this fundamental constant of nature, a redefinition of

First mass measurements with the NIST-4 watt balance

July 10, 2016
Author(s)
Darine El Haddad, Leon S. Chao, Frank C. Seifert, David B. Newell, Jon R. Pratt, Stephan Schlamminger
In the past four years, we have constructed a new watt balance at the National Institute of Standards and Technology (NIST), with the goal to realize the unit of mass after the redefinition of the International System of Units, expected to occur in 2018

A precise instrument to determine the Planck constant, and the future kilogram

June 21, 2016
Author(s)
Darine El Haddad, Frank C. Seifert, Leon S. Chao, David B. Newell, Jon R. Pratt, Carl J. Williams, Stephan Schlamminger, Shisong Li
A precise instrument, called a watt balance, compares mechanical power measured in terms of the meter, the second and the kilogram to electrical power measured in terms of the volt and the ohm. A direct link between mechanical action and the Planck