A5011141069- Graphene research and applications
- Advanced Electron Microscopy Techniques and Applications
- Ion-surface interactions and analysis
- Magnetic properties of thin films
- Electron and X-Ray Spectroscopy Techniques
- Diamond and Carbon-based Materials Research
- Carbon Nanotubes in Composites
- Theoretical and Computational Physics
- Graphene and Nanomaterials Applications
- Quantum and electron transport phenomena
- Integrated Circuits and Semiconductor Failure Analysis
- Molecular Junctions and Nanostructures
- Perovskite Materials and Applications
- Nanowire Synthesis and Applications
- Metal and Thin Film Mechanics
- Solid-state spectroscopy and crystallography
- Magnetic Properties and Applications
- Nanopore and Nanochannel Transport Studies
- Nanoparticles: synthesis and applications
- Advancements in Semiconductor Devices and Circuit Design
- Particle Dynamics in Fluid Flows
- Electronic and Structural Properties of Oxides
- Coagulation and Flocculation Studies
- Physics of Superconductivity and Magnetism
- Advanced Memory and Neural Computing
Pusan National University
2006-2024
Oak Ridge National Laboratory
2017-2020
Georgia Institute of Technology
2009-2019
AID Atlanta
2019
Seoul Medical Center
2019
Center for Nanophase Materials Sciences
2017
Institut Laue-Langevin
2008
Korea Atomic Energy Research Institute
2008
Cornell University
2008
University of California, Los Angeles
2006
We demonstrate that the sub-atomically focused beam of a scanning transmission electron microscope (STEM) can be used to controllably manipulate individual dopant atoms in 2D graphene lattice. manipulation adsorbed source materials and lattice with such vacancy defects passivated by Si substitutional atoms. further these may directed through via e-beam control or modified (as yet, uncontrollably) form new which incorporate into These studies potential STEM for atom-by-atom nanofabrication...
Building materials from the atom up is pinnacle of fabrication. Until recently only platform that offered single-atom manipulation was scanning tunneling microscopy. Here controlled and assembly a few structures are demonstrated by bringing together single atoms using transmission electron microscope. An atomically focused beam used to introduce Si substitutional defects defect clusters in graphene with spatial control nanometers enable motion atoms. The then further manipulated form dimers,...
We demonstrate that one of the most commonly used criteria to ascertain tunneling is dominant conduction mechanism in magnetic tunnel junctions—fits current–voltage (I–V) data—is far from reliable. Using a superconducting electrode and measuring differential conductance below Tc, we divide samples into junctions with an integral barrier having metallic shorts through barrier. Despite clear difference quality, equally reasonable fits I–V data are obtained above Tc. Our results further suggest...
Abstract The ability to engineer the thermal conductivity of materials allows us control flow heat and derive novel functionalities such as rectification, switching cloaking. While this could be achieved by making use composites metamaterials at bulk length-scales, engineering micro- nano-scale dimensions is considerably more challenging. In work, we show that local along a single Si nanowire can tuned desired value (between crystalline amorphous limits) with high spatial resolution through...
We report continuous monitoring of heterogeneously distributed oxygenated functionalities on the entire surface individual graphene oxide flake during chemical reduction process. The charge densities over with mixed oxidized and graphitic domains were observed for same after a step-by-step process using electrostatic force microscopy. Quantitative analysis revealed heavily nanoscale (50–100 nm across) complex mechanism involving leaching sharp asperities from followed by gradual thinning...
CVD grown graphene used in (scanning) transmission electron microscopy ((S)TEM) studies must undergo a careful transfer of the one-atom-thick membrane from growth surface (typically Cu foil) to TEM grid. During this process, invariably becomes contaminated with foreign material. This contamination proves be very problematic (S)TEM because often >95% is obscured and imaging pristine areas results e-beam-induced hydrocarbon deposition which further acts obscure desired area. In article, we...
Advancement of focused electron beam-induced deposition (FEBID) as a versatile direct-write additive nanoscale fabrication technique has been inhibited by poor throughput, limited choice precursors, and restrictions on possible 3D topologies. Here, we demonstrate FEBID using nanoelectrospray liquid precursor injection to grow carbon pure metal nanostructures via direct decomposition electrochemical reduction the relevant achieving growth rates 105 times greater than those observed in...
Reduction in contact resistance is one of the foremost challenges for carbon nanotube/graphene nanodevices. In this study, we present a novel fabrication process low-temperature, Ohmic between open-ended multiwalled nanotubes (MWCNTs) and metal interconnects using graphitic deposited via electron beam-induced deposition (EBID). The electrical structural properties interface are characterized making connection to single (outermost) shell only, as well multiple conducting shells MWCNTs....
Vanadium oxides, such as V 2 O 3 , VO and 5 have attracted considerable attention because of the fascinating physical properties each oxidation state. On other hand, precisely controlling individual states is difficult due to sensitivity oxygen stoichiometry. This article reports that reactive annealing (ROA) can systematically change state vanadium oxide films grown on a c‐Al substrate compared with typical under environments. Chemical, structural, electronic, electrical analysis confirms...
Metallic copper nanoparticles are produced by spray pyrolysis of nitrates with an addition ethanol as cosolvent at 600 degrees C. Depending on the synthesis temperature, two interesting reaction pathways found: below 525 C, approximately 10% hollow Cu(2)O parent particles oxidized to CuO and then reduced Cu, but higher remaining takes a direct path accompanied morphology change. These regimes discussed in aspects phase-transformation kinetics, gas-phase solid-phase thermodynamics, force...
Abstract Electrospinning is a simple versatile process used to produce nanofibers and collect them as nanofiber mat. However, due bending instability, electrospinning often produces mat with non-uniform thickness. In this study, we developed uniform-thickness electrospun (UTEN) production system movable collector based on real-time thickness measurement feedback control. This compatible void regions such mesh-type collector, two-parallel-metal-plate ring-type which facilitates the of light...
Interest in magnetic-tunnel junctions has prompted a re-examination of tunneling measurements through thin insulating films. In any study metal-insulator-metal trilayers, one tries to eliminate the possibility pinholes (small areas over which thickness insulator goes zero so that upper and lower metals trilayer make direct contact). Recently, we have presented experimental evidence ferromagnet-insulator-normal trilayers appear from current-voltage plots be pinhole-free may nonetheless some...
Multiwall carbon nanotubes (MWNTs) are promising candidates for yielding next generation electrical and electronic devices such as interconnects tips conductive force microscopy. One of the main challenges in MWNT implementation is high contact resistance MWNT–metal electrode interface. Electron beam induced deposition (EBID) an amorphous interface has previously been demonstrated to simultaneously lower improve mechanical characteristics MWNT–electrode connection. In this work, we...
We studied the thermally induced phase transformations of electron-beam-induced deposited (EBID) amorphous carbon nanostructures by correlating changes in its morphology with internal microstructure using combined atomic force microscopy (AFM) and high resolution confocal Raman microscopy. These deposits can be used to create heterogeneous junctions electronic devices commonly known as carbon−metal interconnects. compared two basic shapes EBID deposits: dots/pillars widths from 50 600 nm...
The next generation optical, electronic, biological, and sensing devices as well platforms will inevitably extend their architecture into the 3rd dimension to enhance functionality. In focused ion beam induced deposition (FIBID), a helium gas field source can be used with an organometallic precursor fabricate nanoscale structures in 3D high-precision smaller critical dimensions than electron (FEBID), traditional liquid metal FIBID, or other additive manufacturing technology. this work, we...