A5043349273- Force Microscopy Techniques and Applications
- Semiconductor materials and devices
- Molecular Junctions and Nanostructures
- Quantum and electron transport phenomena
- Advanced Electron Microscopy Techniques and Applications
- Integrated Circuits and Semiconductor Failure Analysis
- Surface and Thin Film Phenomena
- Electron and X-Ray Spectroscopy Techniques
- Advancements in Semiconductor Devices and Circuit Design
- Electronic and Structural Properties of Oxides
- Mechanical and Optical Resonators
- Semiconductor Quantum Structures and Devices
- Ga2O3 and related materials
- Photonic and Optical Devices
- Nanowire Synthesis and Applications
- Quantum, superfluid, helium dynamics
- X-ray Spectroscopy and Fluorescence Analysis
- Advanced Chemical Physics Studies
- Advancements in Photolithography Techniques
- Transition Metal Oxide Nanomaterials
- Ion-surface interactions and analysis
- Semiconductor materials and interfaces
- Thermal Radiation and Cooling Technologies
- Topological Materials and Phenomena
- Organic and Molecular Conductors Research
University College London
2017-2025
London Centre for Nanotechnology
2017-2024
Faculty of 1000 (United Kingdom)
2024
University of Toronto
2014-2015
Abstract Atomically precise hydrogen desorption lithography using scanning tunnelling microscopy (STM) has enabled the development of single-atom, quantum-electronic devices on a laboratory scale. Scaling up this technology to mass-produce these requires bridging gap between precision STM and processes used in next-generation semiconductor manufacturing. Here, we demonstrate ability remove from monohydride Si(001):H surface extreme ultraviolet (EUV) light. We quantify characteristics various...
Microwave microscopy enables three-dimensional characterization of atomically thin semiconductor structures with nanometer precision.
Over the past two decades, prototype devices for future classical and quantum computing technologies have been fabricated by using scanning tunneling microscopy hydrogen resist lithography to position phosphorus atoms in silicon with atomic-scale precision. Despite these successes, phosphine remains only donor precursor molecule demonstrated as compatible technique. The potential benefits of placement alternative dopant species have, until now, remained unexplored. In this work, we...
Three-dimensional (3D) electronic band structure is fundamental for understanding a vast diversity of physical phenomena in solid-state systems, including topological phases, interlayer interactions van der Waals materials, dimensionality-driven phase transitions, etc. Interpretation ARPES data terms 3D electron dispersions commonly based on the free-electron approximation photoemission final states. Our soft-X-ray Ag metal reveals, however, that even at high excitation energies states can...
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 direct epitaxy of III–V materials on CMOS-compatible on-axis Si (001) is vital for scalable, cost-effective optoelectronic devices. However, material dissimilarities introduce crystal defects, such as antiphase boundaries (APBs) and threading dislocations (TDs), impairing performance. This study refines surface step stability modeling by incorporating temperature-dependent effects, elucidating single atomic under high-temperature growth conditions. We achieve APB-free through (1) a 10...
In this work, we show the feasibility of extreme ultraviolet (EUV) patterning on an HF-treated silicon (100) surface in absence a photoresist. EUV lithography is leading technique semiconductor manufacturing due to its high resolution and throughput, but future progress can be hampered because inherent limitations resists. We that photons induce reactions partially hydrogen-terminated assist growth oxide layer, which serves as etch mask. This mechanism different from hydrogen desorption...
Artificial lattices constructed from individual dopant atoms within a semiconductor crystal hold promise to provide novel materials with tailored electronic, magnetic, and optical properties. These custom-engineered are anticipated enable new, fundamental discoveries in condensed matter physics lead the creation of new technologies including analog quantum simulators universal solid-state computers. This work reports precise repeatable, substitutional incorporation single arsenic into...
Abstract Single impurities in insulators are now often used for quantum sensors and single photon sources, while nanoscale semiconductor doping features being constructed electrical contacts technology devices, implying that new methods sensitive, non‐destructive imaging of single‐ or few‐atom structures needed. X‐ray fluorescence (XRF) can provide with chemical specificity, comprising as few 100 000 atoms have been detected without any need specialized destructive sample preparation....
The $\mathrm{Si}/{\mathrm{SiO}}_{2}$ interface is populated by isolated trap states that modify its electronic properties. These traps are of critical interest for the development semiconductor-based quantum sensors and computers, as well nanoelectronic devices. Here, we study electric susceptibility with nm spatial resolution using frequency-modulated atomic force microscopy. sample measured here a patterned dopant delta layer buried 2 beneath silicon native oxide interface. We show charge...
The adsorption of up to one monolayer (ML) copper phthalocyanine (CuPc) molecules on a room temperature Cu(111) surface has been studied using scanning tunneling microscopy (STM). Below 1 ML the are in fluid state and highly mobile surface. At coverage coalesce into ordered 2D crystal phase. sub-ML coverages, chemisorption individual CuPc can be induced through exposure electrons at bias voltage exceeding threshold value. This electron effect exploited perform molecular STM lithography.
The progress of miniaturisation in integrated electronics has led to atomic and nanometre-sized dopant devices silicon. Such structures can be fabricated routinely by hydrogen resist lithography, using various dopants such as phosphorous arsenic. However, the ability non-destructively obtain atomic-species-specific images final structure, which would an indispensable tool for building more complex nano-scale devices, quantum co-processors, remains unresolved challenge. Here we exploit X-ray...
We use electrostatic force microscopy to spatially resolve random telegraph noise at the Si/SiO$_2$ interface. Our measurements demonstrate that two-state fluctuations are localized interfacial traps, with bias-dependent rates and amplitudes. These two-level systems lead correlated carrier number mobility a range of characteristic timescales; taken together as an ensemble, they give rise $1/f$ power spectral trend. Such individual defect interface impair performance reliability nanoscale...
We use electrostatic force microscopy to spatially resolve random telegraph noise at the Si/SiO
Dopant impurity species can be incorporated into the silicon (001) surface via adsorption and dissociation of simple precursor molecules. Examples include phosphine (PH3), arsine (AsH3), diborane (B2H6) for incorporation phosphorus, arsenic, boron, respectively. Through exploitation chemistry, spatial locations these dopants controlled at atomic scale patterning a hydrogen lithographic resist layer using scanning tunneling microscopy (STM). There is strong interest in control bismuth atoms...
Two-dimensional dopant layers (δ-layers) in semiconductors provide the high-mobility electron liquids (2DELs) needed for nanoscale quantum-electronic devices. Key parameters such as carrier densities, effective masses, and confinement thicknesses 2DELs have traditionally been extracted from quantum magnetotransport. In principle, are immediately readable one-electron spectral function that can be measured by angle-resolved photoemission spectroscopy (ARPES). Here, buried 2DEL δ-layers...
Growth and thermal behavior of copper‐phthalocyanine (CuPc) fullerene (C 60 ) organic nanocomposite thin films, grown on SiO 2 Cu(111) surfaces, have been studied using scanning electron microscopy, X‐ray diffraction (XRD) tunneling microscopy (STM). It is found that the growth pure CuPc films follows an island‐type mode. The island formation to be dramatically suppressed by inclusion C during deposition. XRD STM studies reveal molecular packing altered upon inclusion, producing disordered...
Germanium has emerged as an exceptionally promising material for spintronics and quantum information applications, with significant fundamental advantages over silicon. However, efforts to create atomic-scale devices using donor atoms qubits have largely focused on phosphorus in Positioning silicon precision requires a thermal incorporation anneal, but the low success rate this step been shown be limitation prohibiting scale-up large-scale devices. Here, we present comprehensive study of...
Recently, phosphorous structures in silicon have been of interest theoretically and experimentally due to their relevance the field quantum computing. Coherent control orbital states shallow donors has demonstrated bulk doped samples. Here we discuss fabrication techniques required 1) obtain patterned two dimensional dilute sheets impurities controlled doping densities 2) get them act as targets for a terahertz laser. Scanning tunnelling microscope hydrogen lithography enables patterning...
The ongoing development of single electron, nano and atomic scale semiconductor devices would benefit greatly from a characterization tool capable detecting electron charging events with high spatial resolution, at low temperature. In this work, we introduce novel Atomic Force Microscope (AFM) instrument measuring critical device dimensions, surface roughness, electrical potential, ultimately the energy levels quantum dots transistors in ultra miniaturized devices. Characterization...
Abstract Three-dimensional (3D) electronic band structure is fundamental for understanding a vast diversity of physical phenomena in solid-state systems, including topological phases, interlayer interactions van der Waals materials, dimensionality-driven phase transitions, etc. Interpretation ARPES data terms 3D electron dispersions commonly based on the free-electron approximation photoemission final states. Our soft-X-ray Ag metal reveals, however, that even at high excitation energies...