A5054163862- Semiconductor materials and devices
- Force Microscopy Techniques and Applications
- Graphene research and applications
- Advancements in Semiconductor Devices and Circuit Design
- Molecular Junctions and Nanostructures
- Surface and Thin Film Phenomena
- Carbon Nanotubes in Composites
- Quantum and electron transport phenomena
- Integrated Circuits and Semiconductor Failure Analysis
- Porphyrin and Phthalocyanine Chemistry
- Nanowire Synthesis and Applications
- Organic and Molecular Conductors Research
- Advanced Electron Microscopy Techniques and Applications
- Ion-surface interactions and analysis
- Mechanical and Optical Resonators
- Advanced Memory and Neural Computing
- 2D Materials and Applications
- Conducting polymers and applications
- Physics of Superconductivity and Magnetism
- Advanced Materials Characterization Techniques
- Diamond and Carbon-based Materials Research
- Semiconductor Quantum Structures and Devices
- Silicon and Solar Cell Technologies
- Electronic and Structural Properties of Oxides
- Thin-Film Transistor Technologies
University of Illinois Urbana-Champaign
2016-2025
Nature Inspires Creativity Engineers Lab
2001-2017
University of Illinois System
2016-2017
University of Nebraska–Lincoln
2016
Samsung (United States)
2003
University of Kentucky
2000
Nokia (Netherlands)
1996
Urbana University
1988
Tsinghua University
1988
Northwestern University
1980-1986
The scanning tunneling microscope has been used to desorb hydrogen from hydrogen-terminated silicon (100) surfaces. As a result of control the dose incident electrons, countable number desorption sites can be created and yield cross section are thereby obtained. Two distinct mechanisms observed: (i) direct electronic excitation Si-H bond by field-emitted electrons (ii) an atomic resolution mechanism that involves multiple-vibrational at low applied voltages. This vibrational heating effect...
Nanoscale patterning of the hydrogen terminated Si(100)-2×1 surface has been achieved with an ultrahigh vacuum scanning tunneling microscope. Patterning occurs when electrons field emitted from probe locally desorb hydrogen, converting into clean silicon. Linewidths 1 nm on a 3 pitch are by this technique. Local chemistry is also demonstrated selective oxidation patterned areas. During oxidation, linewidth preserved and surrounding H-passivated regions remain unaffected, indicating potential...
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...
Ultrathin, lightweight, and flexible aligned single-walled carbon nanotube (SWCNT) films are fabricated by a facile, environmentally friendly, scalable printing methodology. The pattern outstanding intrinsic properties render "metal-like" thermal conductivity of the SWCNT films, as well excellent mechanical strength, flexibility, hydrophobicity. Further, cellular microstructure promotes electromagnetic interference (EMI) shielding ability SWCNTs, leading to effectiveness (SE) ~ 39 90 dB...
We report experimental results that replacing hydrogen with deuterium during the final wafer sintering process greatly reduces hot electron degradation effects in metal oxide semiconductor transistors due to a new giant isotope effect. Transistor lifetime improvements by factors of 10–50 are observed. A plausible physical theory suggests benefits use may be general and also applicable other areas device processing fabrication.
One potential application of molecular nanotechnology is the integration electronic function with advanced silicon technology. step in this process tethering individual molecules at specific locations on surfaces. This paper reports fabrication arrays organic H-passivated Si(100) surfaces patterned an ultrahigh vacuum scanning tunnelling microscope (STM). Feedback controlled lithography (FCL) used to create templates dangling bonds. Molecules introduced gas phase then spontaneously assemble...
A cryogenic UHV scanning tunneling microscope has been used to study the electron stimulated desorption of hydrogen and deuterium from Si(100) surfaces at 11 K. strong isotope effect is observed, as seen previously room temperature. Above $\ensuremath{\sim}5\mathrm{eV}$, yields for H D are temperature independent, while in regime, below 4 eV, a factor $\ensuremath{\sim}300$ easier desorb than 300 This large dependence explained by model that involves multiple vibrational excitation takes...
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTCofacial assembly of partially oxidized metallamacrocycles as an approach to controlling lattice architecture in low-dimensional molecular solids. Chemical, structural, oxidation state, transport, magnetic, and optical properties halogen-doped [M(phthalocyaninato)O]n macromolecules, where M = Si, Ge, SnBruce N. Diel, Tamotsu Inabe, Joseph W. Lyding, Karl F. Schoch Jr., Carl R. Kannewurf, Tobin J. MarksCite this: Am. Chem. Soc. 1983, 105, 6,...
A thermally compensated tube scanner scanning tunneling microscope (STM) has been constructed and successfully tested. This design utilizes two concentric piezoelectric tubes, one for thermal compensation inertial sample translation (over several mm), as well fine adjustment of position while in range. eliminates the need mechanical components such springs, levers, gears, or stepper motors that are known to result considerable vibration sensitivity, drift, low-resonance frequencies. new...
We use scanning tunneling microscopy and spectroscopy to examine the electronic nature of grain boundaries (GBs) in polycrystalline graphene grown by chemical vapor deposition (CVD) on Cu foil transferred SiO(2) substrates. find no preferential orientation angle between grains, GBs are continuous across wrinkles topography. Scanning shows enhanced empty states conductance for most a shift toward more n-type behavior compared bulk graphene. also observe standing wave patterns adjacent...
We examine the transfer of graphene grown by chemical vapor deposition (CVD) with polymer scaffolds poly(methyl methacrylate) (PMMA), poly(lactic acid) (PLA), poly(phthalaldehyde) (PPA), and poly(bisphenol A carbonate) (PC). find that optimally reactive PC provide cleanest transfers without any annealing, after extensive comparison optical microscopy, x-ray photoelectron spectroscopy, atomic force scanning tunneling microscopy. Comparatively, films transferred PLA, PPA, PMMA/PC, PMMA have a...
Abstract Narrow atomically precise graphene nanoribbons hold great promise for electronic and optoelectronic applications, but the previously demonstrated nanoribbon-based devices typically suffer from low currents mobilities. In this study, we explored idea of lateral extension improving their electrical conductivity. We started with a conventional chevron nanoribbon, designed its laterally extended variant. synthesized these new in solution found that results decrease bandgap improvement...
We study interfacial water trapped between a sheet of graphene and muscovite (mica) surface using Raman spectroscopy ultra-high vacuum scanning tunneling microscopy (UHV-STM) at room temperature. are able to image the graphene-water interface with atomic resolution, revealing layered network underneath graphene. identify layer numbers carbon nanotube height reference. Under normal conditions, structures remain stable. However, greater electron energies, we locally manipulate STM tip.
The growth of high-density arrays vertically oriented, single crystalline InAs NWs on graphene surfaces are realized through the van der Waals (vdW) epitaxy mechanism by metalorganic chemical vapor deposition (MOCVD). However, InGaAs results in spontaneous phase separation starting from beginning growth, yielding a well-defined InAs-In(x)Ga(1-x)As (0.2 < x 1) core-shell structure. structure then terminates abruptly after about 2 μm height, and axial uniform composition In(x)Ga(1-x)As takes...
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...
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,...
Fabricating organic semiconducting materials into large-scale, well-organized architectures is critical for building high-performance molecular electronics. While graphene nanoribbons (GNRs) hold enormous promise various device applications, their assembly a well-structured monolayer or multilayer architecture poses substantial challenge. Here, we report the preparation of length-defined monodisperse GNRs via integrated iterative binomial synthesis (IIBS) strategy and self-assembly...
A giant isotope effect of hot electron degradation was found by annealing and passivating integrated circuits recent complementary metal oxide silicon (CMOS) technology with deuterium instead hydrogen. In this paper, we summarize our experience present new results secondary ion mass spectroscopy that correlate accumulation reduced degradation. We also a first account the physical theory view on engineering application point toward rules current voltage scaling as obtained from theory.
Novel solar cells, based on dense arrays of InGaAs nanowires, are grown directly graphene. Here, graphene serves as the conductive back contact and growth template for van der Waals epitaxial assembly vertical nanowires. Although far from being optimum material, core-shell p–n junction In0.25Ga0.75As nanowire demonstrate a conversion efficiency 2.51%, representing new record substrate-free, III-V nanowire-based cells.
Scattering scanning near-field optical microscopy (s-SNOM) has emerged as a powerful nanoscale spectroscopic tool capable of characterizing individual biomacromolecules and molecular materials. However, applications scattering-based techniques in the infrared (IR) to native biosystems still await solution how implement required aqueous environment. In this work, we demonstrate an IR-compatible liquid cell architecture that enables imaging nanospectroscopy by taking advantage unique...
Spatially nonuniform strain is important for engineering the pseudomagnetic field and band structure of graphene. Despite wide interest in engineering, there still a lack control on device-compatible patterns due to limited understanding structure–strain relationship. Here, we study effect substrate corrugation curvature profiles graphene via combined experimental theoretical studies model system: closely packed SiO2 nanospheres with different diameters (20–200 nm). Experimentally,...
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...