A5002780183- Graphene research and applications
- 2D Materials and Applications
- Quantum and electron transport phenomena
- Advanced Memory and Neural Computing
- MXene and MAX Phase Materials
- Molecular Junctions and Nanostructures
- Perovskite Materials and Applications
- Diamond and Carbon-based Materials Research
- Electronic and Structural Properties of Oxides
- Semiconductor materials and devices
- Topological Materials and Phenomena
- Ferroelectric and Negative Capacitance Devices
- Electrochemical Analysis and Applications
- Chalcogenide Semiconductor Thin Films
- Quantum Dots Synthesis And Properties
- Force Microscopy Techniques and Applications
- Semiconductor Quantum Structures and Devices
- Spectroscopy and Quantum Chemical Studies
- Advancements in Battery Materials
- Advanced Thermoelectric Materials and Devices
- Carbon Nanotubes in Composites
- Heusler alloys: electronic and magnetic properties
- ZnO doping and properties
- Semiconductor materials and interfaces
- Mechanical and Optical Resonators
National University of Singapore
2011-2024
École Polytechnique Fédérale de Lausanne
2017-2023
Newcastle University
2021-2022
The presence of direct bandgap and high mobility in semiconductor few-layer black phosphorus offers an attractive prospect for using this material future two-dimensional electronic devices. However, creation barrier-free contacts which is necessary to achieve performance phosphorus-based devices challenging currently limits their potential applications. Here, we characterize fully encapsulated ultrathin (down bilayer) field effect transistors fabricated under inert gas conditions by...
Controlled spin transport in graphene and other two-dimensional materials has become increasingly promising for applications devices. Of particular interest are custom-tailored heterostructures, known as van der Waals that consist of stacks a precisely controlled order. This Colloquium gives an overview this developing field spintronics outlines the experimental theoretical state art.
The possibility of tailoring physical properties by changing the number layers in van der Waals crystals is one driving forces behind emergence two-dimensional materials. One example bulk MoS2, which changes from an indirect gap semiconductor to a direct bandgap monolayer form. Here, we show much bigger tuning range with complete switching metal atomically thin PtSe2 as its thickness reduced. Crystals ~13 nm metallic behavior contact resistance low 70 Ω·µm. As they are thinned down 2.5 and...
We report on the first systematic study of spin transport in bilayer graphene (BLG) as a function mobility, minimum conductivity, charge density, and temperature. The spin-relaxation time τ(s) scales inversely with mobility μ BLG samples both at room temperature (RT) low (LT). This indicates importance D'yakonov-Perel' scattering BLG. Spin-relaxation times up to 2 ns RT are observed lowest mobility. These an order magnitude longer than any values previously reported for single-layer (SLG)....
Defects in solids are unavoidable and can create complex electronic states that significantly influence the electrical optical properties of semiconductors. With rapid progress integration 2D semiconductors practical devices, it is imperative to understand characterize defects this class materials. Here, we examine response defect filling emission using deep level transient spectroscopy (DLTS) reveal their hybridization a monolayer MOCVD-grown material deposited on CMOS-compatible...
We demonstrate injection, transport and detection of spins in spin valve arrays patterned both copper based chemical vapor deposition (Cu-CVD) synthesized wafer scale single layer (SLG) bilayer graphene (BLG). observe relaxation times comparable to those reported for exfoliated samples demonstrating that CVD specific structural differences such as nano-ripples grain boundaries do not limit the present samples. Our observations make Cu-CVD a promising material choice large spintronic applications.
The observation of micron size spin relaxation makes graphene a promising material for applications in spintronics requiring long distance communication. However, dependent scatterings at the contact/graphene interfaces affect injection efficiencies and hence prevent from achieving its full potential. While this major issue could be eliminated by nondestructive direct optical schemes, graphenes intrinsically low orbit coupling strength absorption place an obstacle their realization. We...
Abstract Atomic-scale disorder in two-dimensional transition metal dichalcogenides is often accompanied by local magnetic moments, which can conceivably induce long-range ordering into intrinsically non-magnetic materials. Here, we demonstrate the signature of orderings defective mono- and bi-layer semiconducting PtSe 2 performing magnetoresistance measurements under both lateral vertical measurement configurations. As material thinned down from bi- to mono-layer thickness, observe a...
Hexagonal boron nitride (hBN) has emerged as a promising material platform for nanophotonics and quantum sensing, hosting optically active defects with exceptional properties such high brightness large spectral tuning. However, precise control over deterministic spatial positioning of emitters in hBN remained elusive long time, limiting their proper correlative characterization applications hybrid devices. Recently, focused ion beam (FIB) systems proved to be useful engineer several types...
Reactivity control of graphene is an important issue because chemical functionalization can modulate graphene's unique mechanical, optical, and electronic properties. Using systematic optical studies, we demonstrate that van der Waals interaction the dominant factor for reactivity on two-dimensional (2D) heterostructures. A significant enhancement in stability achieved by replacing common SiO2 substrate with 2D crystals such as additional layer, WS2, MoS2, or h-BN. Our theoretical...
While boron nitride (BN) substrates have been utilized to achieve high electronic mobilities in graphene field effect transistors, it is unclear how other layered two dimensional (2D) crystals influence the performance of graphene. In this Letter, we study surface morphology 2D BN, gallium selenide (GaSe), and transition metal dichalcogenides (tungsten disulfide (WS2) molybdenum (MoS2)) their on graphene's quality. Atomic force microscopy analysis shows that these improved roughness (root...
The preservation and manipulation of a spin state mainly depends on the strength spin–orbit interaction. For pristine graphene, intrinsic coupling (SOC) is only in order few μeV, which makes it almost impossible to be used as an active element future electric field controlled spintronics devices. This stimulates development systematic method for extrinsically enhancing SOC graphene. In this letter, we study weakly fluorinated graphene We observe high non-local signals even without applying...
Time-reversal symmetry and broken spin degeneracy enable the exploration of valley quantum degrees freedom in monolayer transition-metal dichalcogenides. While strength large splitting valance band these materials is now well-known, probing 10-100 times smaller conduction poses significant challenges. Since it easier to achieve n-type most them, resolving energy levels crucial for prospect developing new spintronic valleytronic devices. Here, we study transport high mobility MoS2 devices...
Due to the chemical inertness of 2D hexagonal-Boron Nitride (h-BN), few atomic-layer h-BN is often used encapsulate air-sensitive crystals such as Black Phosphorus (BP). However, effects on Schottky barrier height, doping and contact resistance are not well known. Here, we investigate these by fabricating encapsulated BP transistors with cobalt (Co) contacts. In sharp contrast directly Co contacted p-type devices, observe strong n-type conduction upon insertion at Co/BP interface. First...