A5081665416- Graphene research and applications
- Molecular Junctions and Nanostructures
- Fullerene Chemistry and Applications
- Advanced Chemical Physics Studies
- 2D Materials and Applications
- Surface and Thin Film Phenomena
- nanoparticles nucleation surface interactions
- Organic and Molecular Conductors Research
- Quantum and electron transport phenomena
- Force Microscopy Techniques and Applications
- Diamond and Carbon-based Materials Research
- Electronic and Structural Properties of Oxides
- Topological Materials and Phenomena
- Iron-based superconductors research
- Electron and X-Ray Spectroscopy Techniques
- Semiconductor materials and devices
- Advanced Physical and Chemical Molecular Interactions
- Integrated Circuits and Semiconductor Failure Analysis
- Catalytic Processes in Materials Science
- Theoretical and Computational Physics
- Semiconductor Quantum Structures and Devices
- Chemical and Physical Properties of Materials
- Carbon Nanotubes in Composites
- Boron and Carbon Nanomaterials Research
- Advanced Thermoelectric Materials and Devices
National Taiwan University
2013-2024
National Science and Technology Council
2024
Institute of Atomic and Molecular Sciences, Academia Sinica
2002-2022
Academia Sinica
2022
Shanghai Jiao Tong University
2022
National Center for Theoretical Sciences
2022
National Center for Theoretical Sciences, Physics Division
2022
National Chung Cheng University
2009
Oak Ridge National Laboratory
1996-2001
University of Tennessee at Knoxville
2001
Single layers of transition metal dichalcogenides (TMDCs) are excellent candidates for electronic applications beyond the graphene platform; many them exhibit novel properties including charge density waves (CDWs) and magnetic ordering. CDWs in these single generally a planar projection corresponding bulk because quasi-two-dimensional nature TMDCs; different CDW symmetry is unexpected. We report herein successful creation pristine single-layer ${\mathrm{VSe}}_{2}$, which shows...
The diffusion and coarsening of two-dimensional homoepitaxial islands on Cu(100) Ag(100) surfaces have been studied at room temperature with time-sequenced scanning tunneling microscopy. Quantitative analyses the dependence island coefficient $D$ vs side length $L$, $D\ensuremath{\propto}{L}^{\ensuremath{-}\ensuremath{\alpha}}$, yield noninteger scaling exponents which are consistent coalescence. Moreover, near absence decay shows that occurs via mass transport along periphery.
Two-dimensional (2D) topological insulators (TIs) are promising platforms for low-dissipation spintronic devices based on the quantum spin Hall (QSH) effect, but experimental realization of such systems with a large band gap suitable room-temperature applications has proven difficult. Here, we report successful growth bilayer graphene quasi-freestanding WSe$_2$ single layer 1T' structure that does not exist in bulk form WSe$_2$. Using angle-resolved photoemission spectroscopy (ARPES) and...
We demonstrate that a ${\mathrm{C}}_{60}$ overlayer enhances the perpendicular magnetic anisotropy of Co thin film, inducing an inverse spin reorientation transition from in plane to out plane. The driving force is ${\mathrm{C}}_{60}/\mathrm{Co}$ interfacial we have measured quantitatively situ as function coverage. Comparison with state-of-the-art ab initio calculations show this mainly arises local hybridization between ${p}_{z}$ and ${d}_{{z}^{2}}$ orbitals. By generalizing these...
Abstract Direct growth of graphene integrated into electronic devices is highly desirable but difficult due to the nominal ~1000 °C chemical vapor deposition (CVD) temperature, which can seriously deteriorate substrates. Here we report a great reduction CVD down 50 on sapphire and 100 polycarbonate, by using dilute methane as source molten gallium (Ga) catalysts. The very low temperature synthesis made possible carbon attachment island edges pre-existing nuclei islands, causes no damages A...
Two-dimensional (2D) honeycomb lattices beyond graphene promise new physical properties such as quantum spin Hall effect. While there have been claims of growth (silicene, germanene, stanene), their existence needs further support and preparation characterization remain a difficult challenge. Our findings suggest that two distinct phases associated with the analog made germanium (Ge) instead carbon, can be grown on Ag(111) observed by scanning tunneling microscopy, low-energy electron...
We present a combined study by scanning tunneling microscopy and atomistic simulations of the emission dissociated dislocation loops nanoindentation on (001) fcc surface. The latter consist two stacking-fault ribbons bounded Shockley partials stair-rod dislocation. These loops, which intersect surface, are shown to originate from interstitial character emitted along <110> directions usually located at hundreds angstroms away indentation point. Simulations reproduce nucleation glide these loops.
We demonstrate the charge state of C60 on a Cu(111) surface can be made optimal, i.e., forming C60(3-) as required for superconductivity in bulk alkali-doped C60, purely through interface reconstruction rather than with foreign dopants. link origin to reconstructed ordered (4x4) 7-atom vacancy holes surface. In contrast, adsorbed unreconstructed receives much smaller amount electrons. Our results illustrate definitive effect that affects electronic properties molecule-electrode contact.
This paper reports an experimental observation of the square root q behavior $\ensuremath{\pi}$-plasmons in free-standing graphene. The authors used very high resolution EELS measurements to be able probe plasmonic excitations long wavelength limit.
Two-dimensional materials constitute a promising platform for developing nanoscale devices and systems. Their physical properties can be very different from those of the corresponding three-dimensional because extreme quantum confinement dimensional reduction. Here we report study TiTe2 single-layer to bulk limit. Using angle-resolved photoemission spectroscopy scanning tunneling microscopy spectroscopy, observed emergence (2 × 2) charge density wave order in with transition temperature 92 ±...
We review the features of charge density wave (CDW) conductor $\mathrm{Nb}{\mathrm{S}}_{3}$ (phase II) and include several additional results from transport, compositional, structural studies. Particularly, we highlight three central results: (1) In addition to previously reported CDW transitions at ${T}_{\mathrm{P}1}=360\phantom{\rule{0.16em}{0ex}}\mathrm{K}$ ${T}_{\mathrm{P}2}=150\phantom{\rule{0.16em}{0ex}}\mathrm{K}$, a third transition occurs much higher temperature...
We revisit submonolayer growth of ${\mathrm{C}}_{60}$ on Cu(111) by scanning tunneling microscopy (STM), with emphasis the formation higher-order commensurate metastable states. These phases show concomitant interfacial reconstruction, adlayer buckling, and rotation in order to match as closely possible 10.0 \AA{} nearest neighbor (NN) distance. Most interestingly, a clear correlation between angle molecular contrast patterns is demonstrated. This caused ${\mathrm{C}}_{60}$-induced...
In the rich phase diagram of ${\mathrm{Na}}_{x}{\mathrm{CoO}}_{2}$, $x=0.71$ enjoys special stability and is called Curie-Weiss metal due to its anomalous properties. Similarly, $x=0.84$ prepared from high temperature melt a end point beyond which system separates. Using synchrotron x-ray diffraction on single crystals, we discovered $\sqrt{12}a$ $\sqrt{13}a$ superlattice structures interpret as ordering Na (vacancy) clusters. These results lead picture coexisting local moments itinerant...
Fluorescent nanodiamond (FND) contains nitrogen-vacancy defect centers as fluorophores. The intensity of its fluorescence can be significantly enhanced after deposition the particle (35 or 140 nm in size) on a nanocrystalline Ag film without buffer layer. excellent photostability (i.e. neither photobleaching nor photoblinking) material is preserved even film. Concurrent decrease excited state lifetimes and increase intensities indicate that enhancement results from surface plasmon resonance....
The basic and the charge density wave (CDW) structures of monoclinic ${\mathrm{NbS}}_{3}$-II polymorph were studied by synchrotron x-ray diffraction, ab initio calculations, simulation electron diffraction patterns, atomic-resolution transmission low-temperature scanning tunneling microscopies. It is confirmed that structure belongs to space group $P{2}_{1}/m$ described with a unit cell, formed four pairs symmetry-related trigonal prismatic (TP) columns...
The nature of distinct bright-dim ${\mathrm{C}}_{60}$ contrast and its intricate ordering on Ag(100) is clarified with scanning tunneling microscopy. film (111) close-packed locally distorted rhombic units specific order, forming an incommensurate aperiodic phase. We relate the to interfacial restructuring beneath each dim ${\mathrm{C}}_{60},$ determined by competing interactions in reconstructed interface rhombus configuration.
Detailed combined scanning tunneling microscopy and low-energy electron diffraction measurements reveal that the structure of a ${\mathrm{C}}_{60}$ monolayer on Ag(100) is not previously accepted commensurate $c(6\ifmmode\times\else\texttimes\fi{}4)$ phase but rather an incommensurate (111) close-packed phase. The film exhibits characteristic molecular contrast pattern with merely short-range order, room-temperature fluctuations show thermal equilibrium state reached. nature this...
Using scanning tunneling microscopy and spectroscopy first principles calculations, we have systematically studied the morphological electronic structures of a ${\mathrm{C}}_{60}$ monolayer on Ag(100). Our results reveal that bright-dim contrast has definite geometric origin there are two types dim molecules, one monomer other dimer. With distinctive properties charge transfers in differently adsorbed this is highly inhomogeneous aperiodic.
A detailed and exhaustive structural analysis by low-energy electron diffraction (LEED) is reported for the C${}_{60}$-induced reconstruction of Cu(111), in system Cu(111) $+$ (4 $\ifmmode\times\else\texttimes\fi{}$ 4)-C${}_{60}$. wide LEED energy range allows enhanced sensitivity to crucial C${}_{60}$-metal interface that buried below 7-\AA{}-thick molecular layer. The clearly favors a seven-Cu-atom vacancy model (with Pendry R-factor ${R}_{p}$ $=$ 0.376) over one-Cu-atom (${R}_{p}$ 0.608)...
A systematic study of polycrystalline $1T\ensuremath{-}{\mathrm{TiSe}}_{2\ensuremath{-}\ensuremath{\delta}}$ with controlled Se loss indicates that the unconventional charge density wave (CDW) phase is found to be most pronounced in samples $\ensuremath{\delta}\ensuremath{\sim}0.12$, instead being vacancy free. The level defects and temperature determines whether should categorized as a semiconductor, semimetal, or an excitonic insulator. An interpretation using general band picture $p$-type...
A pinch-off phenomenon is discovered in the evolution of 2D wormlike nanoclusters formed homoepitaxial adlayers. This feature shown to distinguish mass transport via periphery diffusion from other mechanisms. Continuum modeling such accurately describes experimental observations, particularly if one incorporates anisotropy step-edge line tension.
The clean-off reaction of AgO added rows by CO on Ag(110) and Au/Ag(110) bimetallic surfaces was studied scanning tunneling microscopy (STM) compared with density functional theory (DFT). This combined study a model system illustrated the complexity catalytic enhancement in systems. By analyzing situ time-lapsed STM image series, we found that oxidation Au-enriched surface leads to an exponential depletion oxygen time rate is synergistically enhanced presence Au. First principles...