A5027086751- Semiconductor materials and devices
- Graphene research and applications
- Advancements in Semiconductor Devices and Circuit Design
- Quantum and electron transport phenomena
- Surface and Thin Film Phenomena
- Advanced Memory and Neural Computing
- Electronic and Structural Properties of Oxides
- Integrated Circuits and Semiconductor Failure Analysis
- Advanced Surface Polishing Techniques
- Force Microscopy Techniques and Applications
- Silicon and Solar Cell Technologies
- Molecular Junctions and Nanostructures
- 2D Materials and Applications
- Advancements in Photolithography Techniques
- Diamond and Carbon-based Materials Research
- Electron and X-Ray Spectroscopy Techniques
- Advanced Materials Characterization Techniques
- Carbon Nanotubes in Composites
- Semiconductor materials and interfaces
- Advanced Electron Microscopy Techniques and Applications
- Advancements in Battery Materials
- Ion-surface interactions and analysis
- Advanced Measurement and Metrology Techniques
- Graphene and Nanomaterials Applications
- Semiconductor Lasers and Optical Devices
Sandia National Laboratories
2019-2024
Physical Measurement Laboratory
2020-2024
National Institute of Standards and Technology
2018-2024
Sandia National Laboratories California
2020-2021
Joint Quantum Institute
2018-2020
University of Maryland, College Park
2018-2020
United States Naval Research Laboratory
2012-2017
National Academies of Sciences, Engineering, and Medicine
2015-2017
Northwestern University
2016
Zyvex (United States)
2016
Chemical vapor deposition of graphene on Cu often employs polycrystalline substrates with diverse facets, grain boundaries (GBs), annealing twins, and rough sites. Using scanning electron microscopy (SEM), electron-backscatter diffraction (EBSD), Raman spectroscopy Cu, we find that substrate crystallography affects growth more than facet roughness. We determine (111) containing facets produce pristine monolayer higher rate (100) especially Cu(100). The number defects nucleation sites appears...
We analyze the optical, chemical, and electrical properties of chemical vapor deposition (CVD) grown hexagonal boron nitride (h-BN) using precursor ammonia-borane ($H_3N-BH_3$) as a function $Ar/H_2$ background pressure ($P_{TOT}$). Films at $P_{TOT}$ less than 2.0 Torr are uniform in thickness, highly crystalline, consist solely h-BN. At larger $P_{TOT}$, with constant flow, growth rate increases, but resulting h-BN is more amorphous, disordered, $sp^3$ bonded. attribute these changes high...
Direct, tunable coupling between individually assembled graphene layers is a next step towards designer two-dimensional (2D) crystal systems, with relevance for fundamental studies and technological applications. Here we describe the fabrication characterization of large-area (> cm^2), coupled bilayer on SiO2/Si substrates. Stacking two films leads to direct electronic interactions layers, where resulting film properties are determined by local twist angle. Polycrystalline have...
We investigate hyperthermal ion implantation (HyTII) as a means for substitutionally doping layered materials such graphene. In particular, this systematic study characterizes the efficacy of substitutional N-doping graphene using HyTII over an N+ energy range 25–100 eV. Scanning tunneling microscopy results establish incorporation N substituents into lattice during processing. illustrate differences in evolution characteristic Raman peaks following incremental doses N+. use ratios...
Abstract Atomically precise fabrication has an important role to play in developing atom‐based electronic devices for use quantum information processing, materials research, and sensing. Atom‐by‐atom the potential enable control over tunnel coupling, exchange on‐site charging energies, other key properties of basic needed solid‐state computing analog simulation. Using hydrogen‐based scanning probe lithography, individual dopant atoms are deterministically placed relative atomically aligned...
Spin states in semiconductors provide exceptionally stable and noise-resistant environments for qubits, positioning them as optimal candidates reliable quantum computing technologies. The proposal to use nuclear electronic spins of donor atoms silicon, introduced by Kane 1998, sparked a new research field focused on the precise individual impurity devices, utilising scanning tunnelling microscopy ion implantation. This roadmap article reviews advancements 25 years since Kane's proposal,...
Abstract Spin states in semiconductors provide exceptionally stable and noise-resistant environments for qubits, positioning them as optimal candidates reliable quantum computing technologies. The proposal to use nuclear electronic spins of donor atoms silicon, introduced by Kane 1998, sparked a new research field focused on the precise individual impurity devices, utilising scanning tunnelling microscopy ion implantation. This roadmap article reviews advancements 25 years since Kane’s...
We have performed scanning tunneling microscopy and spectroscopy (STM/STS) measurements as well ab initio calculations for graphene monolayers on clean hydrogen(H)-passivated silicon (100) (Si(100)/H) surfaces. In order to experimentally study the same piece both substrates, we develop a method depassivate hydrogen from under Si(100)/H surface. Our work represents first demonstration of successful reproducible depassivation beneath monolayer flakes by electron-stimulated desorption. Ab...
Lithographic precision is as or more important than resolution. For decades, the semiconductor industry has been able to work with ±5% precision. However, for other applications such micronanoelectromechanical systems, optical elements, and biointerface applications, higher desirable. Lyding et al. [Appl. Phys. Lett. 64, 11 (1999)] have demonstrated that a scanning tunneling microscope can be used remove hydrogen (H) atoms from silicon (100) 2 × 1 H-passivated surface through an electron...
Abstract Atomically precise donor-based quantum devices are a promising candidate for solid-state computing and analog simulations. However, critical challenges in atomically fabrication have meant systematic, atomic scale control of the tunneling rates tunnel coupling has not been demonstrated. Here using room temperature grown locking layer over entire process, we reduce unintentional dopant movement while achieving high quality epitaxy scanning tunnelling microscope (STM)-patterned...
Hyperthermal ion implantation offers a controllable method of producing high-quality substitutionally doped graphene with nitrogen, an $n$-type dopant that has great potential for electronics and spintronics applications where high carrier concentration, uniform doping, minimal vacancy defect concentration is desired. Here we examine the transport properties monolayer sheets as function beam energy dose. We observe transition from weak to strong localization varies concentration. For...
Single-layer graphene derived from chemical vapor deposition (CVD) holds promise for scalable radio frequency (RF) electronic applications. However, prevalent low-frequency flicker noise (1/f noise) in CVD field-effect transistors is often up-converted to higher frequencies, thus limiting RF device performance. Here, we achieve an order of magnitude reduction 1/f based on transferred onto silicon oxide substrates by utilizing a processing protocol that avoids aqueous chemistry after...
Abstract The ability to place atoms one by at specific atomic sites was first used create functioning electronic devices in the late 1990s. Since then, process known as precision advanced manufacturing (APAM) has been further developed and both academic commercial interest its potential grown. This article describes nuances of process, explaining that it places dopants into silicon using surface chemistry, a mechanism not typically microfabrication. It also discusses ongoing efforts develop...
Hydrogen atoms on a silicon surface, H–Si (100), behave as resist that can be patterned with perfect atomic precision using scanning tunneling microscope. When hydrogen atom is removed in this manner, the underlying presents chemically active site, commonly referred to dangling bond. It has been predicted individual bonds function artificial atoms, which, if grouped together, form designer molecules (100) surface. Here, we present an ring structure molecule spanning three dimer rows,...
Atomically thin MoS2 has generated intense interest for emerging electronics applications. Its two-dimensional nature and potential low-power are particularly appealing space-bound electronics, motivating the need a fundamental understanding of electronic device response to space radiation environment. In this letter, we quantify field-effect transistors (FETs) vacuum ultraviolet (VUV) total ionizing dose radiation. Single-layer (SL) multilayer (ML) FETs compared identify differences that...
Diborane (B2H6) is a promising molecular precursor for atomic precision p-type doping of silicon that has recently been experimentally demonstrated [Škereň Nat. Electron. 2020]. We use density functional theory (DFT) calculations to determine the reaction pathway diborane dissociating into species will incorporate as electrically active substitutional boron after adsorbing onto Si(100)-2×1 surface. Our indicate must overcome an energy barrier adsorb, explaining observed low sticking...
Abstract Fabrication of quantum devices by atomic-scale patterning with scanning tunneling microscopy (STM) has led to the development single/few atom transistors, few-donor/quantum dot for spin manipulation, and arrayed few-donor analog simulation. We have developed atomic precision lithography, dopant incorporation, device encapsulation, ex situ re-location, contact processes enable high-yield fabrication. In this work, we describe a multiscale alignment strategy using Kelvin probe force...
Two-dimensional, $\ensuremath{\delta}$-doped Si:P structures are of interest for qubits, high-performance electronics, and quantum metamaterials. However, a lack low-resistance, high-yield Ohmic contacts to these subsurface, atomically thin systems has hampered applications. This study demonstrates Pd${}_{2}$Si with yield near 100%, which introduce only small parasitic resistance compatible the low-temperature processing needed an abrupt delta layer. technology enables reliable fabrication...