A5047397185- Quantum and electron transport phenomena
- Surface and Thin Film Phenomena
- Semiconductor materials and devices
- Advancements in Semiconductor Devices and Circuit Design
- Molecular Junctions and Nanostructures
- Electronic and Structural Properties of Oxides
- Surface Chemistry and Catalysis
- Graphene research and applications
- Silicon and Solar Cell Technologies
- Force Microscopy Techniques and Applications
- 2D Materials and Applications
- Quantum Information and Cryptography
- Semiconductor Quantum Structures and Devices
- Mechanical and Optical Resonators
- Physics of Superconductivity and Magnetism
- Advanced Chemical Physics Studies
- MXene and MAX Phase Materials
- Quantum Computing Algorithms and Architecture
- Topological Materials and Phenomena
- Advanced Surface Polishing Techniques
- Electron and X-Ray Spectroscopy Techniques
- Integrated Circuits and Semiconductor Failure Analysis
- Nanowire Synthesis and Applications
- Semiconductor materials and interfaces
- Thin-Film Transistor Technologies
National Institute of Standards and Technology
2014-2024
Physical Measurement Laboratory
2020-2024
Cleveland Clinic
2019
Creative Commons
2019
Center for Nanoscale Science and Technology
2014-2017
University of California, Riverside
2010-2015
Designing high-finesse resonant cavities for electronic waves faces challenges due to short electron coherence lengths in solids. Previous approaches, e.g. the seminal nanometer-sized quantum corrals, depend on careful positioning of adatoms at clean surfaces. Here we demonstrate an entirely different approach, inspired by peculiar acoustic phenomena whispering galleries. Taking advantage graphene's unique properties, namely gate-tunable light-like carriers, create Whispering Gallery Mode...
The phase of a quantum state may not return to its original value after the system's parameters cycle around closed path; instead, wavefunction acquire measurable difference called Berry phase. phases typically have been accessed through interference experiments. Here, we demonstrate an unusual Berry-phase-induced spectroscopic feature: sudden and large increase in energy angular-momentum states circular graphene p-n junction resonators when small critical magnetic field is reached. This...
Sputtering of MoS2 films single-layer thickness by low-energy argon ions selectively reduces the sulfur content material without significant depletion molybdenum. X-ray photoelectron spectroscopy shows little modification Mo 3d states during this process, suggesting absence reorganization or damage to overall structure film. Accompanying ab initio molecular dynamics simulations find clusters vacancies in top plane be structurally stable. Measurements photoluminescence at temperatures between...
The Hubbard model is an essential tool for understanding many-body physics in condensed matter systems. Artificial lattices of dopants silicon are a promising method the analog quantum simulation extended Fermi-Hubbard Hamiltonians strong interaction regime. However, complex atom-based device fabrication requirements have meant emulating tunable two-dimensional Hamiltonian has not been achieved. Here, we fabricate 3 × arrays single/few-dopant dots with finite disorder and demonstrate tuning...
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...
The observation of phonons in graphene by inelastic electron tunneling spectroscopy has been met with limited success previous measurements arising from weak signals and other spectral features which inhibit a clear distinction between miscellaneous excitations. Utilizing back-gated device that allows adjusting the global charge carrier density, we introduce an averaging method where individual spectra at varying density are combined into one representative spectrum. This improves signal for...
The doping of Si using the scanning probe hydrogen depassivation lithography technique has been shown to enable placing and positioning small numbers P atoms with nanometer accuracy. Several groups have now used this capability build devices that exhibit desired quantum behavior determined by their atomistic details. What remains elusive, however, is ability control precise number placed at a chosen site 100% yield, thereby limiting complexity degree perfection achievable. As an important...
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...
Nanoscale confinement of adsorbed CO molecules in an anthraquinone network on Cu(111) with a pore size ≈4 nm arranges the shell structure that coincides distribution substrate confined electronic states. Molecules occupy states approximately sequence rising electron energy. Despite sixfold symmetry boundary itself, adsorbate adopts threefold network-substrate system, highlighting importance even for such quasi-free-electron systems.
Anthraquinone self-assembles on Cu(111) into a giant honeycomb network with exactly three molecules each side. Here we propose that the exceptional degree of order achieved in this system can be explained as consequence confinement substrate electrons pores, pore size tailored so confined adopt noble-gas-like two-dimensional quasi-atom configuration two filled shells. Formation identical pores related adsorption (at different overall periodicity due to molecule size) corroborates concept. A...
Recently, the topological classification of electronic states has been extended to a new class matter known as crystalline insulators. Similar insulators, insulators also have spin-momentum locked surface states, but they only exist on specific crystal planes that are protected by reflection symmetry. Here, we report an ultralow temperature scanning tunneling microscopy and spectroscopy study insulator SnTe nanoplates grown molecular beam epitaxy. We observed quasiparticle interference...
The key building blocks for the fabrication of devices based on deterministic placement dopants in silicon using scanning tunneling microscopy (STM) hydrogen lithography are formation well-defined dopant delta-layers and overgrowth high quality crystalline Si. To develop these capabilities, it is critical importance to quantify movement sub-nanometer regime. this end, we investigate Si:P delta-layer samples produced by fully exposing a Si surface PH3 prior encapsulation with dramatically...
We develop an atomically precise fabrication and metrology strategy to control single dopant movement activation in Si:P monolayers.
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,...
The diffusion and arrangements of CO adsorbates within nanometer-scale pores on a copper surface are investigated by low-temperature scanning tunneling microscopy. In contrast to extended terraces, confinement stabilizes dislocation lines that expose more than one-fourth the adsorbate population potentially reactive adsorption configurations. Confinement allows correlation between diffusivity number in pore. A marked increase is found coincides with absence dense films exposed facets....
Adsorbing anthracene on a Cu(111) surface results in wide range of complex and intriguing superstructures spanning coverage from 1 per 17 to 15 substrate atoms. In accompanying first-principles density-functional theory calculations we show the essential role van der Waals interactions estimating variation adsorption energy height across sample. We can thereby evaluate compression film terms continuum elastic properties, which an effective Young's modulus 1.5 GPa Poisson ratio...
Our ability to access and explore the quantum world has been greatly advanced by power of atomic manipulation local spectroscopy with scanning tunneling force microscopes, where key technique is use atomically sharp probe tips interact an underlying substrate. Here we employ modify quantify interaction between system under study that can strongly affect any measurement in low charge density systems, such as graphene. We transfer Co atoms from a graphene surface onto tip change control...
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...
An Mo2S3 monolayer grown on copper coexists with well-known MoS2 patches and triangular islands. Imaging by scanning tunneling microscopy after exposure to anthraquinone shows the new structure be far more active in adsorption, permitting even formation of a compressed adsorbate layer before other surface areas, including supposedly reactive brim areas islands, capture this adsorbate.
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...
We present a method of analyzing the results density functional modeling molecular adsorption in terms an analogue orbitals. This approach permits intuitive chemical insight into process. Applied to set anthracene derivates (anthracene, 9,10-anthraquinone, 9,10-dithioanthracene, and 9,10-diselenonanthracene), we follow electronic states molecules that are involved bonding process correlate them both geometry species' diffusive behavior. additionally provide computational code easily repeat...
Eine Mo2S3-Monolage kann auf einer Kupfer(111)-Oberfläche in Coexistenz mit dreieckigen MoS2-Inseln und -Monolagen gezüchtet werden. Rastertunnelmikroskopie zeigt, dass Anthrachinon bevorzugt der adsorbiert eine komprimierte Adsorbatlage bildet, bevor es andere Oberflächenbereiche, inklusive reaktiven Randbereiche MoS2-Inseln, besetzt.
Acetylene on Cu(111) is investigated by scanning tunnelling microscopy (STM); a surface pattern previously derived from diffraction measurements can be validated, if the variation of STM image transfer function through absorption an acetylene molecule onto tip apex taken into account. Density functional theory simulations point to balance between short-range repulsive interactions acetylene/Cu(111) associated with stress and longer range attractive as origin ordering.