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Search Publications by: David S Simons (Assoc)

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Displaying 1 - 25 of 74

Improved Uranium Particle Analysis by SIMS using O3- Primary Ions

September 6, 2022
Evan Groopman, Todd Williamson, David S. Simons
We have investigated the use of negative molecular oxygen primary ion beams (i.e., O2- and O3-) to determine the benefits of using such beams for uranium particle SIMS analyses. Typically, O- is the most practical negative primary ion species for both age


October 1, 2021
Todd Williamson, David S. Simons, John D. Fassett
Chronometry (a.k.a age-dating, AD) of materials by bulk mass spectrometric methods is a well-established technique based on analysis protocols that have been used in geological fields and by the non-proliferation communities for many years. Recently, it

Targeted enrichment of 28Si thin films for quantum computing

March 9, 2020
Ke Tang, Hyun S. Kim, Aruna N. Ramanayaka, David S. Simons, Joshua M. Pomeroy
We report on the growth of isotopically enriched 28Si epitaxial films with precisely controlled enrichment levels, ranging from natural abundance ratio of 92.2% all the way to 99.99987 % (0.832 × 10-6 mol/mol 29Si). Isotopically enriched 28Si is regarded

Use of quantum effects as potential qualifying metrics for "quantum grade silicon"

December 30, 2019
Aruna N. Ramanayaka, Ke Tang, Joseph A. Hagmann, Hyun S. Kim, David S. Simons, Curt A. Richter, Joshua M. Pomeroy
Across solid state quantum information, material deficiencies limit performance through enhanced relaxation, charge defect motion, or isotopic spin noise. While classical measurements of device performance provide cursory guidance, specific qualifying

A compact, UHV ion source for enriching 28Si and depositing epitaxial thin films

August 22, 2019
Ke Tang, Hyun S. Kim, Aruna N. Ramanayaka, David S. Simons, Joshua M. Pomeroy
An ultra-high-vacuum (UHV) compatible Penning ion source for growing pure, highly enriched 28Si epitaxial thin films is presented. Enriched 28Si is a critical material for quantum information due to the elimination of nuclear spins and, in some cases, must

Round-Robin Test for the Measurement of Layer Thickness of Multilayer Films by Secondary Ion Mass Spectrometry Depth Profiling

July 4, 2017
David S. Simons, Kyung Joong KIM, Jong S. Jang, Joe Bennett, Mario Barozzi, Akio Takano, Zhanping Li, C. W. Magee
An international round-robin test (RRT) was performed to investigate a method to determine the interface location and the layer thickness of multilayer films by secondary ion mass spectrometry (SIMS) depth profiling as a preliminary study to develop a new

Measurement of Uranium-236 in Particles by Secondary Ion Mass Spectrometry

January 12, 2017
David S. Simons, John D. Fassett
The determination of the relative isotopic abundance by secondary ion mass spectrometry of 236U in uranium-containing material is complicated by the presence of 235U1H+ ions at the same nominal mass as the uranium isotopic peak. The net intensity of the

Enriching and purifying silicon epilayers for quantum information

December 6, 2016
Joshua M. Pomeroy, Kevin J. Dwyer, Ke Tang, Hyun S. Kim, Aruna N. Ramanayaka, David S. Simons
High quality, enriched silicon contains an exceptionally low density of defects and unpaired electron and nuclear spins that allow candidate qubits (single donors or quantum dots) to exhibit very long dephasing times compared to silicon with a natural

Uranium Ion Yields from Monodisperse Uranium Oxide Particles

February 24, 2016
Nicholas E. Sharp, John D. Fassett, David S. Simons
Secondary ion mass spectrometry (SIMS) plays an important role in nuclear forensics through its ability to identify isotopic ratios of particles accurately and precisely from samples obtained by inspectors [1]. As the particle mass can be on the order of

CCQM Pilot Study P-140; Quantitative Surface Analysis of Multi-Element Alloy Films

October 1, 2015
David S. Simons, Christopher W. Szakal, William A. Osborn, Kyung Joong Kim
A pilot study for the quantitative surface analysis of multi-element alloy films has been performed by the Surface Analysis Working Group (SAWG) of the Consultative Committee for Amount of Substance (CCQM). The aim of this pilot study is to ensure the

Enriching 28Si beyond 99.9998 % for semiconductor quantum computing

August 5, 2014
Kevin J. Dwyer, Joshua M. Pomeroy, David S. Simons, June W. Lau, Kristen L. Steffens
Using a laboratory-scale apparatus, we enrich 28Si and produce material with 40 times less residual 29Si than previously reported. Starting from natural abundance silane gas, we offer an alternative to industrial gas centrifuges for providing materials

99.996% 12C films enriched and deposited in situ

June 28, 2013
Kevin J. Dwyer, Joshua M. Pomeroy, David S. Simons
A mass selected ion beam system is used to isotopically enrich and deposit thin films, which are measured to be 99.9961(4)% 12C. In solid state quantum information, isotopic enrichment of materials has allowed significant improvements in the coherence time

Characterization of SiGe Films for use as a National Institute of Standards and Technology (NIST) Microanalysis Reference material (RM 8905)

February 1, 2010
Ryna B. Marinenko, Shirley Turner, David S. Simons, Savelas A. Rabb, Rolf L. Zeisler, Lee L. Yu, Dale E. Newbury, Rick L. Paul, Nicholas W. Ritchie, Stefan D. Leigh, Michael R. Winchester, Lee J. Richter, Douglas C. Meier, Keana C. Scott, D Klinedinst, John A. Small
Bulk SiGe wafers cut from single-crystal boules and two SiGe thick films (4 m and 5 m thick) on Si wafers were evaluated with the electron probe microanalyzer for the extent of heterogeneity and composition for use as reference materials needed by the

Phosphorus Doping of Silicon at Substrate Temperatures Above 600 degC

October 22, 2009
P.E. Thompson, G.G. Jernigan, David S. Simons, P. Chi, B.T. Jonker, O.M.J. van 't Erve
P doping of Si during growth by molecular beam epitaxy (MBE) has been investigated in the temperature regime 700 oC to 870 oC. By designing a growth sequence that fully accounts for the P deposited in a delta-doped layer, and then tracks the P as it

Electron Microprobe Characterization of Si-Ge Alloys and Films for Use as Microanalysis Reference Materials

October 16, 2008
Ryna B. Marinenko, Shirley Turner, Dale E. Newbury, Robert L. Myklebust, Lee L. Yu, Rolf L. Zeisler, David S. Simons, John A. Small
Bulk SiGe wafers cut from single-crystal boules and SiGe thick films on Si wafers were evaluated with the electron probe microanalyzer for the extent of heterogeneity and composition for use as reference standards needed by the microelectronics industry in

Development of Certified Reference Materials of Ion-Implanted Dopants in Silicon for Calibration of Secondary Ion Mass Spectrometers

January 1, 2007
David S. Simons, Robert G. Downing, George P. Lamaze, Richard M. Lindstrom, Robert R. Greenberg, Rick L. Paul, Susannah Schiller, William F. Guthrie
Certified reference materials have been developed for calibration of the concentrations of the most common dopants used in silicon semiconductor technology boron, arsenic, and phosphorus. These materials consist of a single dopant species that is