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Search Publications by: Joseph Hagmann (Assoc)

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Displaying 1 - 20 of 20

Geometric interference in a high-mobility graphene annulus p-n junction device

January 10, 2022
Author(s)
Son Le, Albert Rigosi, Joseph Hagmann, Christopher Gutierrez, Ji Ung Lee, Curt A. Richter
The emergence of interference is observed in the resistance of a graphene annulus pn junction device as a result of applying two separate gate voltages. The observed resistance patterns are carefully inspected, and it is determined that the position of the

Electron-electron interactions in low-dimensional Si:P delta layers

June 15, 2020
Author(s)
Joseph Hagmann, Xiqiao Wang, Ranjit Kashid, Pradeep Namboodiri, Jonathan Wyrick, Scott W. Schmucker, Michael Stewart, Richard M. Silver, Curt A. Richter
Key to producing quantum computing devices based on the atomistic placement of dopants in silicon by scanning tunneling microscope (STM) lithography is the formation of embedded highly doped Si:P delta layers (δ-layers). This study investigates the

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

December 30, 2019
Author(s)
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

Chalcogenide Topological Insulators

November 15, 2019
Author(s)
Joseph A. Hagmann
The purpose of this chapter is to introduce the reader to the chalcogenide materials systems that host the topological insulator phase of quantum matter. Specifically, the HgTe quantum well 2D topological insulator system and the V2VI3-type bismuth- and

Magnetotransport in highly enriched 28Si for quantum information processing devices

November 25, 2018
Author(s)
Aruna N. Ramanayaka, Ke Tang, Joseph Hagmann, Hyun S. Kim, Curt A. Richter, Joshua M. Pomeroy
Elimination of unpaired nuclear spins can result in low error rates for quantum computation; therefore, isotopically enriched 28Si is regarded as an ideal environment for quantum information processing devices. Using mass selected ion beam deposition

Contact and Non-Contact Measurement of Electronic Transport in Individual 2D SnS Colloidal Semiconductor Nanocrystals

September 24, 2018
Author(s)
Adam J. Biacchi, Son T. Le, Brian G. Alberding, Joseph A. Hagmann, Sujitra J. Pookpanratana, Edwin J. Heilweil, Curt A. Richter, Angela R. Hight Walker
Colloidal-based solution syntheses offer a scalable and cost-efficient means of producing 2D nanomaterials in high yield. While much progress has been made towards the controlled and tailorable synthesis of semiconductor nanocrystals in solution, it

Towards superconductivity in p-type delta-doped Si/Al/Si heterostructures

July 30, 2018
Author(s)
Aruna N. Ramanayaka, Hyun Soo Kim, Joseph A. Hagmann, Roy E. Murray, Ke Tang, Neil M. Zimmerman, Curt A. Richter, Joshua M. Pomeroy, Frederick Meisenkothen, Huairuo Zhang, Albert Davydov, Leonid A. Bendersky
In pursuit of superconductivity in p-type silicon (Si), we are using a single atomic layer of aluminum (Al) sandwiched between a Si substrate and a thin Si epi-layer. The delta layer was fabricated starting from an ultra high vacuum (UHV) flash anneal of

Quantifying Atom-scale Dopant Movement and Electrical Activation in Si:P Monolayers

January 26, 2018
Author(s)
Xiqiao Wang, Joseph A. Hagmann, Pradeep N. Namboodiri, Jonathan E. Wyrick, Kai Li, Roy E. Murray, Frederick Meisenkothen, Alline F. Myers, Michael D. Stewart, Richard M. Silver
Doped semiconductor structures with ultra-sharp dopant confinement, minimal lattice defects, and high carrier concentrations are essential attributes in the development of both ultra- scaled conventional semiconductor devices and emerging all-silicon

Weak localization thickness measurements of embedded phosphorus delta layers in silicon produced by PH3 dosing

January 23, 2018
Author(s)
Joseph A. Hagmann, Xiqiao Wang, Pradeep N. Namboodiri, Jonathan E. Wyrick, Roy E. Murray, Michael D. Stewart, Richard M. Silver
The key building blocks for devices based on the deterministic placement of dopants in silicon are the formation of phosphorus dopant monolayers and the overgrowth of high quality crystalline Si. Lithographically defined dopant delta-layers can be formed

Epitaxially-grown self-assembled Bi2Se3/Bi2MnSe4 multilayer heterostructures

August 14, 2017
Author(s)
Joseph A. Hagmann, Xiang Li, Si-Ning Dong, Sergei Rouvimov, Sujitra J. Pookpanratana, Kin Man Yu, Tatyana Orlova, Curt A. Richter, David G. Seiler, Xinyu Liu, Jacek K. Furdyna, Margaret Dobrowolska
Progress in understanding topologically non-trivial systems offers the promise of predicting novel systems that demonstrate the remarkable properties associated with topological systems, such as unidirectional spin-polarized surface current and the

Towards single atom devices for quantum information and metrology: weak localization in embedded phosphorus delta layers in silicon

June 29, 2017
Author(s)
Joseph A. Hagmann, Xiqiao Wang, Pradeep N. Namboodiri, Jonathan E. Wyrick, Roy E. Murray, Michael D. Stewart, Richard M. Silver, Curt A. Richter
The key building block for devices based on the deterministic placement of dopants in silicon is the formation of phosphorus dopant monolayers and the overgrowth of high quality crystalline Si. Lithographically defined dopant delta-layers can be formed

Interacting nanoscale magnetic cluster arrays in molybdenum oxide bronzes

May 26, 2017
Author(s)
Joseph A. Hagmann, Son T. Le, Lynn F. Schneemeyer, Joseph A. Stroscio, Tiglet Besara, Theo Siegrist, Curt A. Richter, David G. Seiler
In this study, we examine several reduced ternary molybdates in the family of rare earth molybdenum bronzes produced by electrochemical synthesis with composition LnMo16O44. These compounds contain an array of electrically isolated but magnetically

Elucidating the Structural and Electronic Properties of Solution-Synthesized 2D SnS Crystals

March 28, 2017
Author(s)
Adam J. Biacchi, Brian G. Alberding, Son T. Le, Joseph A. Hagmann, Sugata Chowdhury, Curt A. Richter, Edwin J. Heilweil, Angela R. Hight Walker
The vast majority of nanoscale 2D materials are synthesized by exfoliation or gas phase deposition techniques. Alternatively, bottom-up colloidal solution syntheses offer a scalable and cost-efficient means of producing 2D nanomaterials in high yield

Atomically precise device fabrication

December 7, 2016
Author(s)
Joseph A. Hagmann, Xiqiao Wang, Pradeep N. Namboodiri, Richard M. Silver, Curt A. Richter
An improved capacity to control matter at the atomic scale is central to the advancement of nanotechnology. The complementary metal-oxide-semiconductor (CMOS) devices that power existing computing technology, which continue to scale down in size as
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