A5060480693- 2D Materials and Applications
- MXene and MAX Phase Materials
- Graphene research and applications
- Machine Learning in Materials Science
- Perovskite Materials and Applications
- Advanced Electron Microscopy Techniques and Applications
- Electron and X-Ray Spectroscopy Techniques
- Chalcogenide Semiconductor Thin Films
- Electronic and Structural Properties of Oxides
- Magnetic properties of thin films
- Quantum Dots Synthesis And Properties
- Nanowire Synthesis and Applications
- Theoretical and Computational Physics
- Advanced Condensed Matter Physics
- Advanced Sensor and Energy Harvesting Materials
- Ion-surface interactions and analysis
- Domain Adaptation and Few-Shot Learning
- Ferroelectric and Negative Capacitance Devices
- Topological Materials and Phenomena
- Supercapacitor Materials and Fabrication
- Block Copolymer Self-Assembly
- Ga2O3 and related materials
- Plant nutrient uptake and metabolism
- Advanced X-ray Imaging Techniques
- Photonic Crystals and Applications
National University of Singapore
2017-2025
Duke-NUS Medical School
2018
Abstract Among van der Waals layered ferromagnets, monolayer vanadium diselenide (VSe 2 ) stands out due to its robust ferromagnetism. However, the exfoliation of VSe is challenging, not least because flake extremely unstable in air. Using an electrochemical approach with organic cations as intercalants, 1T‐VSe flakes are successfully obtained from bulk crystal at high yield. Thiol molecules further introduced onto surface passivate exfoliated flakes, which improves air stability for...
Ferroelectric thin film has attracted great interest for nonvolatile memory applications and can be used in either ferroelectric Schottky diodes or tunneling junctions due to its promise of fast switching speed, high on-to-off ratio, nondestructive readout. Two-dimensional α-phase indium selenide (In2Se3), which a modest band gap robust properties stabilized by dipole locking, is an excellent candidate multidirectional piezoelectric switchable photodiode applications. However, the...
Controlled substitutional doping of two-dimensional transition-metal dichalcogenides (TMDs) is fundamental importance for their applications in electronics and optoelectronics. However, achieving p-type conductivity MoS2 WS2 challenging because natural tendency to form n-type vacancy defects. Here, we report versatile growth monolayer by liquid-phase mixing a host tungsten source niobium dopant. We show that crystallites with different concentrations substitutionally doped Nb up 1014 cm-2...
The catalytic and magnetic properties of molybdenum disulfide (MoS2) are significantly enhanced by the presence edge sites. One way to obtain a high density sites in two-dimensional (2D) film is introducing porosity. However, large-scale bottom-up synthesis porous 2D MoS2 remains challenging correlation growth conditions atomic structures edges not well understood. Here, using molecular beam epitaxy, we prepare wafer-scale nanoporous films under Mo flux study their properties....
A spontaneous growth and assembly of non-layered Ni–B<sub>i</sub> into 2D nanosheets onto a graphene support, which demonstrate superior photo electro catalytic performance over pure aggregates.
Molybdenum diselenide (MoSe2) is a promising two-dimensional material for next-generation electronics and optoelectronics. However, its application has been hindered by lack of large-scale synthesis. Although chemical vapor deposition (CVD) using laboratory furnaces applied to grow (2D) MoSe2 cystals, no continuous film over macroscopically large area produced due the uniform control in these systems. Here, we investigate molecular beam epitaxy (MBE) 2D on hexagonal boron nitride (hBN)...
Abstract Fabrication of materials in the monolayer regime to acquire fascinating physical properties has attracted enormous interest during past decade, and remarkable success been achieved for layered adopting weak interlayer van der Waals forces. However, fabrication metal membranes possessing strong intralayer bonding remains elusive. Here, suspended Mo are fabricated from MoSe 2 films via selective electron beam (e‐beam) ionization Se atoms by scanning transmission microscopy (STEM). The...
Abstract Molybdenum carbide (Mo 2 C), a class of unterminated MXene, is endowed with rich polymorph chemistry, but the growth conditions various polymorphs are not understood. Other than most commonly observed T ‐phase Mo C, little known about other phases. Here, C crystals successfully grown consisting mixed and polytypes via diffusion‐mediated mechanism, using liquid copper as diffusion barrier between elemental precursors C. By controlling thickness layer, crystal can be controlled highly...
Alloying 2D transition metal dichalcogenides has opened up new opportunities for bandgap engineering and phase control. Developing a simple scalable synthetic route is therefore essential to explore the full potential of these alloys with tunable optical electrical properties. Here, direct synthesis monolayer WTe2x S2(1-x) via one-step chemical vapor deposition (CVD) demonstrated. The exhibit two distinct phases (1H semiconducting 1T ' metallic) under different compositions, which can be...
Manipulation of lattice strain is emerging as a powerful means to modify the properties low-dimensional materials. Most approaches rely on external forces induce strain, and role interlayer van der Waals (vdW) coupling in generating profiles homobilayer transition metal dichalcogenide (TMDC) films rarely considered. Here, by applying atomic-resolution electron microscopy density functional theory calculations, we observed that mirror twin boundary (MTB) modifies vdW bilayer TMDC films,...
Abstract Understanding the mechanisms and kinetics of defect annihilations, particularly at atomic scale, is important for preparation high‐quality crystals realizing full potential 2D transition metal dichalcogenides (TMDCs) in electronics quantum photonics. Herein, by performing situ annealing experiments an resolution scanning transmission electron microscope, it found that stacking faults rotational disorders multilayered can be healed grain boundary (GB) sliding, which works like a...
Photodetectors usually operate in the wavelength range with photon energy above bandgap of channel semiconductors so that incident photons can excite electrons from valence band to conduction generate photocurrent. Here, however, we show monolayer WS2 photodetectors detect even lying 219 meV below at room temperature. With increase excitation 620 680 nm, photoresponsivity varies 551 59 mA/W. This anomalous phenomenon is ascribed upconversion, which a combination effect one-photon and...
Abstract Enabled by the advances in aberration‐corrected scanning transmission electron microscopy (STEM), atomic‐resolution real space imaging of materials has allowed a direct structure‐property investigation. Traditional ways quantitative data analysis suffer from low yield and poor accuracy. New ideas field computer vision machine learning have provided more momentum to harness wealth big sophisticated information STEM analytics, which transformed localized characterization technique...
Defects are commonly found in two-dimensional (2D) transition-metal dichalcogenide (TMD) materials. Such defects usually dictate the optical and electrical properties of TMDs. It is thus important to develop techniques characterize directly with good spatial resolution, specificity, throughput. Herein, we demonstrate that Kelvin probe force microscopy (KPFM) a versatile technique for this task. able unveil defect heterogeneity 2D materials resolution 10 nm energy sensitivity better than meV....
Characterizing materials to atomic resolution and first-principles structure-property prediction are two pillars for accelerating functional discovery. However, we still lacking a rapid, noise-robust framework extract multilevel structural motifs from complex complement, inform, guide our models. Here, present machine learning that rapidly extracts hierarchy of atomically resolved images. We demonstrate how such motif hierarchies can reconstruct specimens with various defects. Abstracting...
The intercalation of magnetic atoms into van der Waals (vdW) gaps offers a unique opportunity to manipulate the Dzyaloshinskii–Moriya interaction (DMI) and structures by modifying local atomic in vdW magnets. Herein, new strategy is proposed for DMI disrupting atomic-scale order within Cr sublattice Cr-intercalated 2H-TaS2, i.e., Cr1/3TaS2, which enables significant efficient modulation across wide range controlling degree disorder. Lorentz transmission electron microscopy reveals pronounced...
Twisting the angle between van der Waals stacked 2D layers has recently sparked great interest as a new strategy to tune physical properties of materials. The twist and associated strain profiles govern electrical optical twisted materials, but their detailed atomic structures remain elusive. Herein, using combined atomic-resolution electron microscopy density functional theory (DFT) calculations, we identified five unique types moiré features in commensurately 7a×7a transition metal...
Transition metal oxide powders have been widely used as the growth precursors for monolayer transition dichalcogenides (TMDCs) in chemical vapor deposition (CVD). It has proposed that gas phase undergo a two-step reaction during CVD growth, where sub-oxides are likely formed first and then sulfurization of these leads to formation TMDCs. However, effects stoichiometry on TMDC monolayers not studied yet. In this contribution, we report critical role WO3 precursor pre-annealing process WS2...
The burgeoning field of twistronics, which concerns how changing the relative twist angles between two materials creates new optoelectronic properties, offers a novel platform for studying twist-angle dependent excitonic physics. Herein, by surveying range hexagonal phase transition metal dichalcogenides (TMD) twisted homobilayers, we find that 21.8 ± 1.0°-twisted (7a×7a) and 27.8 (13a×13a) bilayers account nearly 20% total population in solution-phase restacked can be found also chemical...
Abstract The intercalation of magnetic atoms into van der Waals (vdW) gaps offers a versatile approach for manipulating local ordering in vdW magnets. However, these intercalated are often intricately positioned within the gaps, resulting an ambiguous impact on interactions and spin configurations. Herein, atomic structures self‐intercalated prototype materials Cr 1+δ Te 2 comprehensively investigated using transmission electron microscopy, elucidating correlation between concentration...
A continuing challenge in atomic resolution microscopy is to identify significant structural motifs and their assembly rules synthesized materials with limited observations. Here, we propose validate a simple effective hybrid generative model capable of predicting unseen domain boundaries potassium sodium niobate thin film from only small number observations, without expensive first-principles calculations or atomistic simulations growth. Our results demonstrate that complicated boundary...